In the summer of 1978 three entrepreneurs in Searcy, Arkansas, a town of 11,000, turned half of an old house into a tanning clinic. Eighteen months later TIME counted at least a dozen franchise chains, with names like Tantalize, Tantrific Sun, and Tan Four Seasons. A typical booth was about three feet square, lined with reflectors and Westinghouse tubes that drew about 560 watts, and a timer shut the tubes off after one to five minutes. "One minute under the lamps is said to equal an hour in the summer sun," the magazine reported. It added where the tubes came from: "Doctors have long used them to treat serious skin conditions; the franchisers have merely put them in tanning booths." 1
The furniture was often "early Gilligan's Island", rattan and white wicker under palm trees, and customers could tan in a bathing suit "or take their rays in the buff". People with psoriasis were "supposedly turned away". Madhukar Pathak, a research professor of dermatology at Harvard Medical School, told the magazine, "we don't know the long-term effects of exposure to ultraviolet lamps." Deborah MacLean managed a salon in Worcester, Massachusetts. "Look, there are no guarantees in life," she told the magazine, and "you just do it in moderation." 1
A tanning bed, a hospital psoriasis cabinet, a red-light face mask, a gel-nail dryer, and a winter light box are all lamps that people buy or are treated with. Tanning beds are the best measured of them. In England in 2010 and 2011, 9 in every 10 of the 402 sunbeds measured gave out more burning ultraviolet than the European limit allows, and across 18 studies, people who had ever tanned indoors had 1.40 times the risk of basal or squamous cell carcinoma, the common skin cancers other than melanoma, of people who never had. In the United States, 3.5 percent of adults, about 7.8 million people, tanned indoors in 2015, and 6.7 percent of them said a tanning device had burned them in the past year. 2; 3; 4
Of the 183 studies in our library that used an artificial lamp or device, by our reading about 15 concern a device that someone buys or is treated with. The rest use a lamp as a laboratory instrument on cells or small patches of skin. The library holds no study of an ultraviolet (UV) nail lamp and no human trial of a red-light panel, a light-emitting diode (LED) mask, or a 10,000-lux light box, so what this page says about those devices comes from regulators' files and from papers we read outside the library. The melanoma evidence on sunbeds is on the melanoma page.
This page covers the light cabinets that came before the sunbed, what sunbeds put out and what was measured in the people who used them, how the marketing and the rules changed, the hospital machines that treat skin disease, and the red-light devices, nail dryers, and light boxes sold for home use. Each study is named by its exposure: real sun, a lamp or device on people, cells in a dish, or a record of what people remembered.
Key facts
- In England in 2010 and 2011, 9 in every 10 of 402 sunbeds measured gave out more burning ultraviolet than the European limit of 0.3 watts per square meter. Weighted for skin cancer, their average output was 0.99, against 0.43 for Mediterranean noon sun. 2
- The US performance standard for sunlamp products, in force since 1980, requires a timer, an off switch, goggles, and a warning label, and sets no limit on how much ultraviolet a bed gives out. 5
- Across 9 studies, people who had ever tanned indoors had 1.58 times the risk of squamous cell carcinoma of people who never had. 3
- The first over-the-counter LED wrinkle device was cleared by the US Food and Drug Administration (FDA) in 2008 because its light matched an earlier professional model's, with a test that lay users could follow the instructions. By September 2026 the agency had cleared 163 such devices. 6; 7
- In a 2006 Canadian trial of 96 people with winter depression, 30 minutes each morning in front of a 10,000-lux light box and a daily antidepressant pill each brought a response in 67 percent. 8
Kellogg's 1891 light bath gave out mostly heat; Wolff's 1975 sunbed filtered its lamps to UVA
John Harvey Kellogg built his first incandescent light bath at the Battle Creek Sanitarium in Michigan in 1891. He patented it in 1896 as a "Radiant-Heat Bath", "a substitute for Turkish and Russian baths" that brought on sweating "at a much lower temperature". A German visitor saw one at the Chicago Exposition of 1893 and began making them at home, and "Hundreds of Light Institutes were opened in the leading cities" of Germany. Kellogg wrote that King Edward of England was cured of gout by a series of light baths in Hamburg and had the bath installed at Windsor and Buckingham palaces. 9; 10
Kellogg knew his bulbs gave off little ultraviolet, which he called chemical rays. "Light from an incandescent lamp contains a very small proportion of chemical rays," he wrote in 1910, because the filament burned at a low temperature and the glass of the bulb held those rays back. Of the arc lamp he wrote, "Excepting sunlight and the magnesium light, no light is so effective chemically as the electric arc light." 9
Arc lamps and mercury-quartz lamps treated skin disease for decades afterward. In a 1999 case report, two dermatologists in Yokohama listed the Finsen, Kromayer, cadmium, and Takayama lamps as the "artificial sunlight" used for more than thirty years against fungal infections, alopecia areata, vitiligo, impetigo, erysipelas, acne, eczema, psoriasis, and tuberculosis. Once antibiotics and steroid medicines arrived, the lamps kept only a few of those diseases, and fluorescent tubes replaced the lamps. 11
Friedrich Wolff, a German, applied for his sunbed patent in August 1975. A sunlamp of the time, his application explained, reached the burn dose "within minutes", "well before the skin begins to exhibit even a slight trace of tanning". Wolff filtered his lamps to "only rays in the range of 315 to 400 nanometers", the band called UVA, which burns only in large doses. He kept the heat low enough that a tan could come from "a single continuous exposure", and the United States granted the patent in June 1978, the summer the Searcy clinic opened. 12
When Wolff died, Cosmedico, the Wolff family's lamp company, gave his motives: "To imitate sunlight and thus counteract winter depression, to create a place to recharge one's batteries and even then to stimulate vitamin D formation." The salon tubes that TIME described gave off both UVA and UVB, the shorter band that causes most sunburn. "Unlike the infra-red sun lamps used at home, these lights give off very little heat," the magazine noted. In 2003 the International Commission on Non-Ionizing Radiation Protection (ICNIRP) wrote that growing evidence of long-term harm from UVA had led the industry "to increase the UVB content in the emission spectrum of tanning lamps in order to more closely simulate natural sun exposure". "This change has also permitted shorter tanning exposures," it added. 13; 1; 14
US rules since 1979 require a timer, goggles, and a warning, and set no limit on a sunbed's ultraviolet
The FDA published its performance standard for sunlamp products in November 1979, and it covers every sunlamp and tanning tube made since May 1980. The shortest ultraviolet, below 260 nanometers, may be no more than 0.003 of the output between 260 and 320. The timer may not run longer than the maker's own recommended maximum, the user must be able to switch the lamps off by hand, and goggles must come with the bed for as many people as it is meant to hold. The tubes must not fit an ordinary household screw socket. 5
None of these rules limits how much ultraviolet a bed gives out. The required label warns that "overexposure can cause eye and skin injury and allergic reactions" and that "Repeated exposure may cause premature aging of the skin and skin cancer." Its last line reads, "If you do not tan in the sun, you are unlikely to tan from the use of this product." 5
The European standard caps a sunbed's erythemally weighted output, its ultraviolet counted by the power to redden skin, at 0.3 watts per square meter. ICNIRP's 2003 statement sorted tanning appliances into four types by that weighting and said that type 4, mostly UVB, "should not be used for tanning purposes". It recommended against ultraviolet appliances "for tanning or other non-medical purposes" and against unattended or coin-operated beds. "A 'safe' level of solarium use does not exist," the statement reads. The US National Toxicology Program has listed exposure to sunlamps or sunbeds as "known to be a human carcinogen" since 2000. 2; 14; 15
Sunbeds measured in Switzerland and England gave out more UVA than summer noon sun
In 2002 a Swiss group published the ultraviolet spectra of the sunbed models that made up more than half of the Swiss market. In the UVB the beds were similar to the sun, and in the UVA they reached "values 10 to 15 times higher". Their average burning output, 0.33 watts per square meter, corresponded to a UV index of 13, against 8.5 for high-summer sun at noon at middle latitudes. The UV index is the number weather forecasts give for the strength of burning sunlight. 16
Between October 2010 and February 2011 a British team measured 402 tanning units on site across England. Their burning output ranged from 0.10 to 1.32 watts per square meter, with an average of 0.56, and only 10 percent were within the European limit of 0.3. Weighted for the power to cause skin cancer instead of redness, the average came to 0.99, against 0.43 for Mediterranean noon sun. For the same time of exposure, the team wrote, the skin cancer risk "was up to six times higher". 2
In 2008 a biology group at Ferris State University in Big Rapids, Michigan, put flasks of human skin cells in a commercial tanning bed made by Wolff System Technology and under a solar simulator, a lamp built to copy sunlight, and gave both the same dose. At the bottom of the flask the bed delivered 135 watts per square meter of UVA and the simulator 49, at the same 1.7 watts of UVB. The team covered the top of each flask with tin foil to block the bed's upper bank of tubes. Two of the 17 authors came from a local school district's math and science center. 17
In 2016 the European Commission's Scientific Committee on Health, Environmental and Emerging Risks (SCHEER) wrote that the output of a modern tanning appliance "corresponds to an UV index of 12, i.e. equivalent to midday Equatorial sun". It put the median yearly dose from artificial tanning at 20 to 30 minimal erythema doses, each the dose that leaves a person's skin just visibly red a day later. By the committee's comparison, the face of an indoor worker at European middle latitudes receives 40 to 160 a year from the sun. The committee wrote that there is "no threshold level" of ultraviolet dose "for the induction of skin cancer" and concluded that "there is no safe limit for exposure to UV radiation from sunbeds." 18
Eight years of sunbed tanning in Liège left skin stretchier and less elastic
In Liège, Belgium, 65 women aged 31 to 46, all of skin type III and all lifelong residents of the region, came to the University Hospital's skin bioengineering laboratory every quarter for 100 months. The researchers described them as "avid sunbed and sunshine worshippers" who used commercial tanning salons "on a regular basis to maintain a deep tan". At each of 33 visits, at least two days after a tanning session, the team held a suction probe with a 2-millimeter opening to the inside of both forearms and recorded how far the skin stretched and how it came back. By the last visit the skin stretched 18.3 percent further, the energy it lost in each stretch had risen 113.1 percent, and its elasticity had fallen 14.3 percent. 19
The women reported "a few short episodes of itching and discrete erythema after any given tanning session", erythema being the medical word for redness. "Sunbeds were outfitted with non-prescription lamps," the authors wrote. "Irradiance measurements were not performed." The women also sunbathed, and there was no comparison group, because the motivation of volunteers "for accepting many measurement sessions would have failed quite rapidly". 19
In Leiden in 2001, dermatologists tanned the backs of 25 volunteers aged 18 to 34 three times a week for three weeks under Cleo Natural lamps from Philips Lighting. The doses started at half of what reddened each person's skin and rose each session. By the end, the epidermis, the outer layer of skin, was 42 percent thicker. Philips supported the first author, and a Philips scientist provided the lamps "and many useful technical recommendations." The paper recommends that people who tan easily and plan a trip to warm countries "might consider increasing their UV tolerance by repetitive exposures to tanning lamps", twice a week, and it notes that the protection was bought with DNA damage from the course itself. 20
"Indoor tanning is not safer than the sun," the Leiden authors wrote, "but the use of timers and the possibility of easily regulating the exposure frequency could make it safer than the attitude of millions of people who want to get a tan during the first days of their sunny holidays." 20
In a 1998 study in Aarhus, Denmark, five healthy volunteers had nine whole-body sessions within three weeks in a commercial solarium fitted with 24 to 26 Osram tubes. The exposed skin held almost twice the enkephalin of skin kept covered with black tape. Enkephalins are among the body's own opioid chemicals. A single lamp dose of UVA raised skin enkephalin about sixfold within 18 hours, and the same burn dose of UVB did not change it. 21
Indoor tanners had more squamous cell carcinoma and thousands of emergency visits a year
The poolings of sunbed and melanoma studies from 2006 to 2021, and the objections to them, are on the sunburn, tanning, and melanoma page. The 2021 meta-analysis cited there, a study that pools the results of earlier studies, also combined 18 studies of basal and squamous cell carcinoma, 10,406 cases in all. People who had ever tanned indoors had 1.40 times the risk of never-users for the two cancers together, 1.58 times for squamous cell carcinoma across 9 studies, and 1.24 times for basal cell carcinoma across 10. For basal cell carcinoma the true figure could be anywhere from no increase to about one and a half times. 3
People who first tanned indoors before age 20 had 2.02 times the risk, and those who went 10 or more times a year 1.56 times. For squamous cell carcinoma, home sunlamps came out at 1.72 times across 2 studies and sunbeds at 1.48 times across 5. Thirteen of the 18 studies were case-control studies, which ask people about their tanning after the diagnosis. The five cohort studies, which asked before anyone was ill, gave 1.48. 3
In Montreal, Francine Aubry and Brenda MacGibbon identified 311 people diagnosed with squamous cell carcinoma in 12 hospitals in 1977 and 1978 and matched each with two patients from the same hospital, most of whom had harmless growths such as seborrheic keratoses. A questionnaire asked, among much else, about "use of long- and round-tube sunlamp". After allowing for coloring, ancestry, and sun at work and at leisure, people who had used a long-tube sunlamp had a relative risk of 13.42, about 13 times the risk of those who had not. The interval around that figure ran from 1.38 to 130.48, so the true increase could have been anywhere from small to more than a hundredfold. The authors called the association "strong", and they also wrote of "the low participation rate in this study". 22
From 2003 to 2012, US hospital emergency departments treated an estimated 3,234 injuries a year from indoor tanning, according to researchers at the Centers for Disease Control and Prevention (CDC), whose coders read the records of a national sample of 66 hospitals. Skin burns made up 79.5 percent, fainting 9.5 percent, and eye injuries 5.8 percent. Of the injured, 82.2 percent were female and 35.5 percent were aged 18 to 24. The yearly count fell from 6,487 in 2003 to 1,957 in 2012. In 2010, 11.7 million American adults tanned indoors. 23; 4
The FTC barred the claim that indoor tanning is safer than the sun in 2010
In March 2008 the Indoor Tanning Association, a trade group of tanning salons and equipment suppliers, began a national advertising campaign in newspapers, on television, and online. The Federal Trade Commission (FTC) charged that the campaign made false claims, among them that indoor tanning is approved by the government and that "Indoor tanning is safer than tanning outdoors because the amount of ultraviolet light received when tanning indoors is monitored and controlled". The association settled in January 2010. 24
Under the settlement, association ads that tie tanning to vitamin D must carry a notice. "You do not need to become tan for your skin to make vitamin D," it begins. "Exposure to ultraviolet radiation may increase the likelihood of developing skin cancer and can cause serious eye injury." David Vladeck, head of the FTC's consumer protection bureau, said the industry's messages "fly in the face of scientific evidence." 24
In 2012 the minority staff of the House Energy and Commerce Committee reported what salons told teenagers. Investigators, some of them college interns, telephoned 300 salons, at least three in every state and the District of Columbia, and said they were fair-skinned 16-year-old girls thinking of tanning for the first time. Ninety percent of the salons said indoor tanning posed no health risk, and 51 percent denied that it would raise the risk of skin cancer, calling the idea "a big myth", "rumor", and "hype". Four in five said tanning would benefit a teenage girl's health, and three quarters would let a first-time customer tan every day, against the FDA's advice of no more than three sessions in the first week. 25
Salons often sent the callers to two websites of the International Smart Tan Network, a tanning trade association. One called tanning "nature's sunscreen". It suggested that indoor tanners make a "sufficient" level of vitamin D, non-tanners a "deficient" level, and dermatologists a "severe deficiency". 25
Teenage indoor tanning in the US fell by two thirds from 2009 to 2017, and the federal age limit was withdrawn in 2026
In the national Youth Risk Behavior Survey, the share of US high school students who had tanned indoors in the past year fell from 15.6 percent in 2009 to 5.6 percent in 2017. Among white female students it fell from 37.4 percent to 10.1 percent. In the surveys from 2009 to 2015, 41,313 students in all, female students in states with age limits tanned indoors 47 percent less, and laws that only required a parent's permission showed no link. Between 1992 and 2023, 184 bills on indoor tanning were introduced in 49 of the 50 states and in the District of Columbia, and 22 states and the District enacted a ban for anyone under 18. 26; 27; 28
In 2014 the FDA moved tanning lamps from class I, its lowest-risk group, to class II, which requires notice to the agency before sale, and ordered a label in letters at least 10 millimeters high: "Attention: This sunlamp product should not be used on persons under the age of 18 years." In December 2015 it proposed a rule that would bar use by anyone under 18 and require adults to sign a risk acknowledgement. After more than 8,100 comments, the agency withdrew the proposal on 16 March 2026, citing "concerns regarding possible unintended consequences" and alternatives proposed in the comments. The notice is signed by Robert F. Kennedy, Jr., the Secretary of Health and Human Services. 29; 30; 31
Brazil banned tanning equipment for cosmetic use in 2009, and in April 2025 its health regulator, Anvisa, banned the lamps as well, to stop anyone building or repairing the beds. Commercial solariums became illegal across most of Australia on 1 January 2015 and in Western Australia a year later, and the Northern Territory had none. By mid-December 2014, Queensland had removed 88 beds from 35 licensees, whose owners had been offered "an incentive payment" to surrender them early. Owning a sunbed and using it at home remains legal in Australia. 32; 33; 34
In England and Wales, the Sunbeds (Regulation) Act 2010 requires sunbed businesses to make sure that no one under 18 uses their beds. 35
Hospital phototherapy cabinets are dosed to each patient's skin, and a PUVA chamber cost US$24,960
The FDA regulates ultraviolet lamps for skin disease under a separate rule from tanning sunlamps. The 10 percent federal tax on indoor tanning, in force since July 2010, excludes "any phototherapy service performed by a licensed medical professional". 31; 36 Narrowband UVB, one of the main hospital treatments, comes from tubes that give off a narrow band at 311 to 313 nanometers. 37
In Bogotá, dermatologists measured the minimal erythema dose of 113 people aged 18 to 56 in a narrowband UVB cabin that delivered 4.3 milliwatts per square centimeter at 15 centimeters. The median dose that reddened the skin rose with skin type, from 390 millijoules per square centimeter for type I to 885 for type IV. The authors cited a British series of 352 psoriasis patients whose medians were lower at every type, 200 for type I and 550 for type IV. Measuring that dose, they wrote, is essential in the "use of phototherapy". 38
In New Delhi, dermatologists at the All India Institute of Medical Sciences priced their PUVA cabinet when they tested it against sunlight in a 2013 trial for psoriasis. PUVA pairs a pill of psoralen, which makes skin more sensitive to light, with UVA from the cabinet, and the New Delhi dose started at 2 joules per square centimeter for skin type IV and 2.5 for type V, rising by 0.5 each session. The Waldmann 8001 K chamber had cost US$24,960 in 1998, drew 3 kilowatts, and needed about US$1,200 a year in maintenance and US$1,610 in tubes and other replacements. The team costed it on 3,992 hours of use a year, and a whole course of PUVA for one patient used a median 5.85 hours. 39
"PUVA treatment requires sophisticated artificial UV light chambers with high initial and running costs," the New Delhi authors wrote. 39 In 2021 a dermatologist in Gurugram, India, called hospital visits and home narrowband units "huge impediments" and treated a flight attendant's vitiligo with a filter cream and sunlight instead. Staff of Cadila Healthcare supplied all of the cream, and the other drugs, free to the patient. 37
In July 1996 a 63-year-old furniture dealer came to the Kanagawa Cancer Center in Yokohama with a red, eroded plaque 5 by 6 centimeters on his right leg, inside a brown patch 9 by 12. Ten years earlier he had injured the leg. A local clinic had treated the eczema and erosion that followed with a Takayama sunlamp, a mercury-quartz lamp, 30 times over three years, "each of 5 or 6 seconds". Surgeons removed an area 11 by 12 centimeters and grafted it, and the tumor was a basosquamous carcinoma, with features of both basal and squamous cell cancer. The authors believed the lamp had caused it, and they also wrote that thirty sessions that short "would seem incapable of causing skin cancer without some other factor such as trauma or long-term scratching." 11
In photodynamic therapy, daylight cleared keratoses nearly as well as the red lamp, with far less pain
Photodynamic therapy (PDT) treats actinic keratoses, the rough, scaly patches of sun-damaged skin that sometimes turn into squamous cell carcinoma. A cream is spread on the patches, the damaged cells turn it into a light-sensitive chemical, and light then activates the chemical and kills them. In a clinic the light comes from a red lamp. In daylight PDT the patient sits outdoors, and a consensus paper cited in the Australian trial below put the time at two hours. 40
In a 2014 trial funded by Galderma, the maker of the cream, 100 people at seven Australian centers had one side of the face or scalp treated under the red lamp and the other side in daylight. The area treated on each side was limited to 8 by 18 centimeters, "the field size of the Aktilite lamp". At 12 weeks the lamp side had cleared 92.8 percent of mild lesions and the daylight side 89.2 percent. Pain averaged 5.7 out of 10 on the lamp side and 0.8 on the daylight side. Two of the authors were Galderma employees and a third had been one. 40
In Irvine, California, 80 patients sat for two and a half hours in outdoor shade, "generally in their backyard", and the only costs were the drug and its application. On the second day, when a shorter session brought mild burning, "some patients elected to go outside protocol and 'tough it out' despite more significant discomfort." 41
A hospital in the UK that wanted daylight treatment sheltered from rain chose a transparent Perspex geodesic dome with ultraviolet filtering for a garden next to its dermatology unit. The hospital's estate management objected on safety grounds, "including risks from falling animals", which delayed the project. The dome went up in June 2025 and cost £3,300 in all. Rain fell during six sessions, and all were completed. 42
Red-light wrinkle devices are cleared as equivalent to devices already sold, and their trials are small
By September 2026 the FDA had cleared 163 devices under its code for light-based over-the-counter wrinkle reduction, each through a premarket notification, called a 510(k), which shows that a new device is "substantially equivalent" to one already sold. A federal regulation says that such a finding "does not in any way denote official approval of the device", and that implying approval "is misleading and constitutes misbranding". 7; 43
The first home LED wrinkle device, the GentleWaves Consumer, was cleared in February 2008 "for over-the-counter use in the treatment of periorbital wrinkles and rhytides", the lines around the eyes. Its clearance summary rests on testing that found "no significant difference in spectral content" from a professional GentleWaves model cleared earlier. "Thus, performance and safety testing obtained for the cleared GentleWaves is fully applicable," it reads. The only new study was "a user study" to confirm that lay users could follow the instructions. 6
In 2018 a review of 31 randomized trials of LEDs in dermatology gave acne, cold sores and shingles, and wound healing a grade of B, and skin rejuvenation, from six trials, a C. In one of those six, 23 patients treated with red LEDs at 630 nanometers showed no improvement in skin elasticity or moisture over untreated skin. The reviewers listed samples under 20, no blinding, and no sham device among the trials' limits. 44
A 2014 German trial put 113 volunteers under two kinds of full-body red and near-infrared light, twice a week for 30 sessions, and compared them with a comparison group of 23. Blinded ratings of photographs, skin roughness, and collagen density on ultrasound improved in the treated groups. One of the trial's two authors listed JK-International GmbH in Windhagen as an affiliation, the company that builds Ergoline tanning beds. 45; 46
In 2023 a systematic review of red and near-infrared light for aging skin found "no relevant clinical trial data linking PBM with any significant adverse events, including the finding of a new or recurrent malignancy." PBM stands for photobiomodulation, the name for low-level red and near-infrared light used to change how cells behave. Tumor studies in animals, the review found, "yield varied results with no clear pattern emerging." South Australia's environment regulator counts collariums, beds sold to stimulate collagen, under its ban on commercial tanning. "Some collariums produce UV light in the prohibited range," it explains. 47; 48
Our library holds no human trial of a red-light panel or an LED mask. Its nearest studies are cell work with infrared lamps and the heat removed. In Paris in 1998, a 250-watt infrared bulb over dishes of skin cells kept cool on a water-cooled plate protected them from UVA, which killed 45 percent of the cells alone and 15 percent after one infrared exposure. In Düsseldorf in 2007 and 2010, skin cells under a water-filtered Hydrosun infrared A lamp made more reactive oxygen species, corrosive forms of oxygen, in their mitochondria. The lamp switched on MMP-1, an enzyme that cuts collagen, and changed the activity of 599 genes. 49; 50; 51
One trial of red light for sleep enrolled 20 players from a Chinese army women's basketball team. The 10 given 30 minutes of whole-body red light every night for 14 days improved in sleep scores and blood melatonin against 10 given no light and no sham device. 52
Nail lamps give off UVA, and no study has followed the people who use them
In 2009 two dermatologists reported two healthy middle-aged women, with no personal or family history of skin cancer, who had developed non-melanoma skin cancers on the backs of their hands after exposure to UV nail lights. The observation "warrants further investigation", they wrote. In 2012 Brian Diffey modeled the risk and estimated that "tens or hundreds of thousands of women would need to use a UVA nail lamp regularly" for one of them to develop a squamous cell carcinoma on the back of the hand because of it. Fingerless gloves, he wrote, would cut it "to virtually zero". 53; 54
In 2013 two researchers tested six UV nail lamps from major US makers. At the distance of a hand, the lamps fell into risk group 1 or 2, low to moderate, with a permissible daily exposure of 29.8 to 276.25 minutes, and at 20 centimeters they fell in the exempt group, the lowest. 55
An Australian team tested eight nail dryers sold in Australia for home use and reported in 2021 what they gave off. Seven were LED and one a compact fluorescent, and all eight emitted UVA, from 39.0 to 184.9 watts per square meter; only the fluorescent one gave a trace of UVB. Seven of the eight took more than an hour to reach the exposure limit, and a manicure usually takes 1 to 10 minutes under the lamp. Only one carried a warning about ultraviolet, and the price of a dryer "was not an indicator" of lower ultraviolet output. 56
Our library holds no nail-lamp study of any kind. In a 2023 study of mouse and human skin cells in dishes, one 20-minute session under a nail dryer killed 20 to 30 percent of the cells, and the authors wrote that their study "does not provide direct evidence for an increased cancer risk in human beings". 57 A 2024 review found nine studies, three of them case reports, and wrote that "the available evidence is weak". 58
Light boxes for winter depression act through the eyes and filter out ultraviolet
In 1980 Alfred Lewy's group at the National Institute of Mental Health (NIMH) reported that bright artificial light suppressed the nighttime melatonin of six people, where ordinary room light did not. That December the group treated Herbert Kern, whom Lewy later called "the first self-identified patient with SAD", seasonal affective disorder, with 2,500 lux from 6 to 9 in the morning and 4 to 7 in the afternoon. Lux measures how bright light looks to the eye, and indoor rooms usually run at 300 to 500. Kern's depression "began to remit in a few days, and the response was complete within two weeks." 59; 60; 61
Kern, a 63-year-old engineer with a crew cut, had kept records of his mood swings since 1967 and was sure they followed the seasons. He had joined the American Society of Photobiology to test the idea. The 1982 report of his treatment lists him as one of its four authors. After a Washington Post story about the work, thousands of readers wrote in. 62; 63
In 1984 Norman Rosenthal and the NIMH group described 29 patients and gave the condition its name. "Preliminary studies in 11 patients suggest that extending the photoperiod with bright artificial light has an antidepressant effect," they wrote. In 1987 the group gave 10 patients light to the eyes and, separately, light to the skin, and the effect "was much greater" through the eyes. "However, patients' expectations nearly always predicted the outcome," the authors added. 64; 65
The light box NIMH describes gives 10,000 lux for 30 to 45 minutes a day, usually first thing in the morning. It is "about 20 times brighter than ordinary indoor light" and "filters out the potentially damaging UV light". In the Can-SAD trial, run at four Canadian centers over three winters, 96 patients were assigned by chance to 30 minutes each morning of a 10,000-lux fluorescent box with a dummy pill, or a dim 100-lux box with fluoxetine, an antidepressant. In each group 67 percent responded, and 50 and 54 percent went into remission. The authors noted that the trial had no group given both a dim box and a dummy pill. 66; 8
A 2020 meta-analysis of 19 trials found bright light better than dim light or sham devices, with 1.42 times the response rate. The true figure could be anywhere from about 1.1 to 1.9 times, and the authors rated the trials' risk of bias as moderate to high. For preventing winter depression in people who had had it before, a 2019 Cochrane review found one eligible trial, of 46 people, and its authors drew no conclusion from it. 67; 68
In 2019 three researchers tested 24 light therapy devices that 12 makers had lent or donated. Seven met their criteria of at least 7,000 lux at 12 inches, spread evenly and without glare, and some devices sold as "10,000-lux" reached it "only at unreasonably close distances". "The U.S. Food and Drug Administration has yet to approve any light therapy device for depression and has not regulated such devices," they wrote. One of the three had received research funding for clinical trials from The Litebook Company. 69
Our library holds no trial of a 10,000-lux box. In Novosibirsk, Siberia, in 1997 and 1998, a Russian, Swiss, and American team woke nine young men to a computer-driven halogen lamp over the bed that rose from 0.001 to 1,000 lux along the curve of a June dawn at 50 degrees north. Over six mornings in the laboratory, the simulated dawn held their body clocks steady, while a flat 0.1 lux let them drift later by at least 42 minutes. The rights to two patents on the system belong to a New York psychiatric research foundation, and one of the authors, Michael Terman, is named on both. 70
The lamp the FDA cleared in January 2026 "to stimulate production of Vitamin D" is a different device. The SOLIUS PRO, for people 22 and older, is a panel of UVB LEDs peaking at 293 nanometers and aimed at the torso, and its app scans the user's face for the supplied goggles before each session. It was cleared as equivalent to the Sperti Sun Lamp Model P-164, a lamp sold before 1976 and never itself cleared, on optical tests and a study of 27 users of all six skin types. The summary lists no measurement of vitamin D in anyone's blood. The Sperti lamp's intended use, as the summary gives it, was to "Activate sterols in the skin converting them to essential Vitamin D". 71
Misconceptions
What people believe
- Tanning beds are safer than the sun because the dose is controlled.
- Worldwide, indoor tanning causes more skin cancers than smoking causes lung cancers.
- Ninety-seven percent of young women with melanoma used tanning beds.
- A red-light device cleared by the FDA has been proven to work.
- A SAD lamp works by making vitamin D in the skin.
What the studies show
- US rules set no limit on a bed's output, and 9 in 10 of 402 English sunbeds exceeded the European limit. The FTC barred the "monitored and controlled" safety claim in 2010. 5; 2; 24
- The one comparison of the two that we found, a 2014 meta-analysis, covered the United States, Northern and Western Europe, and Australia, and its skin cancers were mostly basal and squamous cell carcinomas. Its authors wrote that "the mortality associated with lung cancer is far greater than that for skin cancer." 72; 73
- In the Minnesota study behind that figure, 61 of 63 women diagnosed before 30 had tanned indoors, and so had 51 of 61 women of the same age without melanoma. Before adjustment, women who had tanned were about six times as likely to be in the melanoma group, and the true figure could be anywhere from about 1.3 to 28.5 times. 74; 73
- FDA clearance of these devices means equivalence to a device already sold. The first home LED wrinkle device was cleared on its light spectrum and a test of whether lay users could follow the instructions. 6; 43
- The light boxes used for winter depression filter out ultraviolet and work through the eyes, and the skin needs UVB to make vitamin D. 66; 65; 73
Questions people ask
Can tanning beds cause skin cancer?
The US National Toxicology Program lists exposure to sunlamps or sunbeds as a known human carcinogen. Across 9 studies, people who had ever tanned indoors had 1.58 times the risk of squamous cell carcinoma of people who never had, and the melanoma estimates are on the melanoma page. 15; 3
Can you get skin cancer from one tanning bed session?
No study has measured the effect of one session. The pooled estimates compare people who had ever used a sunbed with people who never had, and risk rose with earlier and more frequent use, to 2.02 times for basal and squamous cell carcinoma in people who first tanned before 20. 3
Are tanning beds safer than the sun?
The FTC charged the Indoor Tanning Association with making that claim falsely and barred it in 2010. Measured Swiss sunbeds gave out 10 to 15 times the UVA of the sun, and English sunbeds, weighted for skin cancer, averaged more than twice the output of Mediterranean noon sun. 24; 16; 2
Can red light therapy cause skin cancer?
A 2023 systematic review found no clinical trial linking red or near-infrared light to a new or recurring cancer. Studies of tumors in animals gave varied results with no clear pattern. Some collagen beds sold with red light also give off ultraviolet, according to South Australia's regulator. 47; 48
Does red light therapy work for wrinkles?
A 2018 review of LED trials gave skin rejuvenation a C grade from six small trials, and one of them found no change in elasticity. A 2014 trial of full-body red light, with an author from a tanning bed maker, found improved roughness and collagen density against a comparison group of 23. 44; 45
Can UV nail lamps cause skin cancer?
No study has followed nail lamp users. Two women with hand cancers were reported in 2009, and a 2012 model estimated that tens or hundreds of thousands of women would need to use the lamps regularly for one extra squamous cell carcinoma on the hands. 53; 54 A nail dryer damaged the DNA of skin cells in dishes in 2023, and a 2024 review of nine studies judged the evidence weak. 57; 58
Are LED nail lamps safer than UV nail lamps?
LED nail lamps are UV lamps. Seven of eight home dryers tested in Australia were LED, all eight gave off UVA, and price did not predict output. 56
Can blue light from screens damage your skin?
No study in our library tested screens on human skin. Measured in Yokohama in August, a smartphone at the screen gave off 1/251 of the sun's blue light, and a laptop 1/566. On five volunteers' hands, 10 minutes of a blue LED set to the blue in direct sunlight dimmed the natural glow of flavins, the skin molecules the authors think absorb blue light, by about 8 percent. 75; 76
Do SAD lamps give you vitamin D?
The light boxes used for seasonal affective disorder filter out ultraviolet, and the skin needs UVB to make vitamin D. A UVB panel was cleared in 2026 to stimulate vitamin D, and its clearance summary lists no blood measurement. 66; 73; 71
Can you use an IPL hair-removal device on tanned skin?
In a Copenhagen trial paid for by Procter and Gamble, a home intense pulsed light (IPL) device reddened 24 of 80 test sites on skin tanned under a solar simulator, against 7 of 80 on the same volunteers' untanned skin. No redness lasted past an hour. Two of the authors worked for Procter and Gamble, one of them at its Braun unit in Germany. 77
Can tanning beds damage your eyes?
Eye injuries were 5.8 percent of the tanning injuries treated in US emergency departments from 2003 to 2012, and the US standard requires goggles that let through no more than a thousandth of the UVB. 23; 5
What we do not know
Nobody has followed nail lamp users. The human evidence is case reports, and how much UVA reaches a hand over years of manicures has not been measured on real customers.
Our library holds no human trial of a consumer red-light panel, LED mask, or photobiomodulation device. The trials outside it are small and often unblinded, and one of them had an author from a tanning bed maker.
The light box trials are small, and the 2020 meta-analysis rated their risk of bias as moderate to high. Only one trial of light to prevent winter depression met the Cochrane review's criteria. 67; 68
No study we found measured the ultraviolet a salon customer received and followed her to a diagnosis. The cancer studies asked people to remember their tanning, most of them after they were ill. The longest study of sunbed users in our library measured their skin 33 times over eight years, and it did not measure the beds.
Key studies
- Gerber and colleagues, 2002, Switzerland. Measured sunbeds. Their UVA ran 10 to 15 times the sun's, and their average output matched a UV index of 13. 16
- Tierney and colleagues, 2013, England. Measured 402 sunbeds on site. Nine in 10 exceeded the European limit. 2
- Hoerter and colleagues, 2008, Michigan. Cells under a tanning bed and a solar simulator. The bed gave 135 watts per square meter of UVA against 49. 17
- Quatresooz and colleagues, 2011, Liège. Commercial sunbeds and sun, 65 women measured over 100 months. Skin elasticity fell 14.3 percent, and the beds were not measured. 19
- De Winter and colleagues, 2001, Leiden. Tanning lamps on 25 volunteers' backs, with support from Philips. The epidermis grew 42 percent thicker. 20
- Nissen and colleagues, 1998, Aarhus. Nine sessions in a commercial solarium. Skin enkephalin almost doubled. 21
- Aubry and MacGibbon, 1985, Montreal. A questionnaire. Long-tube sunlamp users had 13.42 times the risk of squamous cell carcinoma. 22
- An and colleagues, 2021. Pooled 18 studies of recalled indoor tanning. Ever-users had 1.58 times the risk of squamous cell carcinoma. 3
- Guy and colleagues, 2015, United States. Emergency department records. An estimated 3,234 tanning injuries a year. 23
- Holman and colleagues, 2019, United States. A national school survey. Indoor tanning fell from 15.6 to 5.6 percent of high school students. 26
- Miyamoto and Okajima, 1999, Yokohama. A sunlamp on one man's injured leg. A basosquamous carcinoma after 30 sessions of 5 or 6 seconds. 11
- Aggarwal and colleagues, 2013, New Delhi. A PUVA cabinet against sunlight. The chamber had cost US$24,960. 39
- Valbuena and colleagues, 2020, Bogotá. A narrowband UVB cabin on 113 people. The burn dose rose from 390 to 885 millijoules per square centimeter across skin types I to IV. 38
- Rubel and colleagues, 2014, Australia. A red lamp against daylight on the same faces. Clearance of 92.8 against 89.2 percent, and pain of 5.7 against 0.8. 40
- Jagdeo and colleagues, 2018. A review of 31 LED trials. Skin rejuvenation graded C. 44
- Wunsch and Matuschka, 2014, Germany. Full-body red and near-infrared light on 113 volunteers against a comparison group of 23. Roughness and collagen density improved. 45
- Glass, 2023. A review of red and near-infrared light for aging skin. No trial linked it to cancer. 47
- Diffey, 2012. A risk model for nail lamps. Tens or hundreds of thousands of regular users for one extra cancer on the hands. 54
- Ford and colleagues, 2021, Australia. Eight home nail dryers measured. All gave off UVA. 56
- Wehr and colleagues, 1987, NIMH. Light to the eyes against light to the skin in 10 patients. The eyes gave the larger effect. 65
- Lam and colleagues, 2006, Canada. A light box against fluoxetine in 96 patients. Sixty-seven percent responded to each. 8
- Oldham, Oldham, and Desan, 2019. Measured 24 light therapy devices. Seven met the authors' criteria. 69
- Danilenko and colleagues, 2000, Novosibirsk. A simulated dawn over the bed of nine men. It held their body clocks steady. 70
- Tsuchida and Sakiyama, 2023, Yokohama. Measured screens and August sun. A phone gave 1/251 of the sun's blue light. 75
- Thaysen-Petersen and colleagues, 2014, Copenhagen. A home IPL device on tanned and untanned skin. Redness at 24 of 80 against 7 of 80 sites. 77
Definitions
- Actinic keratosis. A rough, scaly patch of sun-damaged skin, also called solar keratosis. A small share become squamous cell carcinomas.
- Basal cell carcinoma. The commonest skin cancer, which grows from cells at the base of the epidermis.
- Collarium. A bed sold to stimulate collagen with light. South Australia's regulator found that some give off ultraviolet.
- Erythema. Redness of the skin, the visible sign of a sunburn.
- Infrared A. The shortest band of infrared, from about 760 to 1,440 nanometers, which reaches deep into skin.
- Intense pulsed light (IPL). A flash lamp used in clinics and home devices to remove hair.
- Irradiance. The power of light falling on a surface, in watts per square meter or milliwatts per square centimeter.
- LED. Light-emitting diode, a small semiconductor light that gives out a narrow band of color.
- Lux. A measure of how bright light looks to the human eye. Indoor rooms usually run at 300 to 500 lux, and the light boxes used for winter depression at 10,000.
- Meta-analysis. A study that pools the results of earlier studies into one estimate.
- Minimal erythema dose. The smallest dose of ultraviolet that leaves a patch of a person's skin just visibly red a day later.
- Narrowband UVB. Ultraviolet B from tubes with a narrow band at 311 to 313 nanometers, used in hospitals for psoriasis, vitiligo, and other skin diseases.
- Photobiomodulation. Low-level red and near-infrared light used to change how cells behave, sold as red light therapy.
- Photodynamic therapy. A treatment in which a cream on the skin is turned by damaged cells into a light-sensitive chemical, which light then activates to kill them.
- Premarket notification, or 510(k). The FDA route by which a device is cleared as substantially equivalent to one already sold. Federal rules say that clearance is not approval.
- PUVA. A psoralen pill, which makes skin more sensitive to light, followed by UVA from a lamp.
- Relative risk. How many times more common a disease is in one group than in another.
- Seasonal affective disorder. Depression that returns at the same season each year, usually winter.
- Solar simulator. A lamp built to give off a spectrum close to that of sunlight.
- Squamous cell carcinoma. A skin cancer of the flat cells near the surface of the skin, most common on skin that sees the most sun.
- Sunbed. A tanning bed or booth lined with tubes that give off mostly UVA, used for cosmetic tanning. US rules call it a sunlamp product.
- UV index. The scale weather forecasts use for the strength of the sun's burning ultraviolet.
- UVA. Ultraviolet from 315 to 400 nanometers. It is most of a sunbed's output and burns only in large doses.
- UVB. Ultraviolet from 280 to 315 nanometers. It causes most sunburn.
Statistics
Pooling 18 studies with 10,406 cases, people who had ever used an indoor tanning device (a sunbed or sunlamp) had 1.40 times the risk of non-melanoma skin cancer of never-users, with a 95 percent interval of 1.18 to 1.65. 3
Across 9 studies, people who had ever used an indoor tanning device had 1.58 times the risk of squamous cell carcinoma of never-users (1.38 to 1.81). 3
Across 10 studies, people who had ever used an indoor tanning device had 1.24 times the risk of basal cell carcinoma of never-users, on an interval of 1.00 to 1.55 whose lower end touches no difference. 3
For non-melanoma skin cancer diagnosed before age 50, 4 studies put the risk of people who had ever tanned indoors at 1.81 times that of never-users (1.38 to 2.37). 3
Before age 50, the single study of squamous cell carcinoma put indoor tanners' risk at 1.99 times never-users' (1.48 to 2.68), and 3 studies of basal cell carcinoma put it at 1.79 (1.15 to 2.77). 3
For squamous cell carcinoma, sunlamp use carried 1.72 times the risk of never-users across 2 studies (1.16 to 2.53) and sunbed use 1.48 times across 5 studies (1.20 to 1.83). 3
For basal cell carcinoma, 2 sunbed studies gave a relative risk of 4.41 on an interval of 1.10 to 77.08, while 2 sunlamp studies gave 1.21 (0.75 to 1.95), which does not clear chance. 3
Of the 36 melanoma studies, 28 reported device type separately: sunlamp use carried 1.31 times the melanoma risk of never-users across 9 studies (1.04 to 1.64) and sunbed use 1.17 times across 19 studies (1.05 to 1.31). 3
Across 6 studies each, people who first tanned indoors before age 20 had 2.02 times the non-melanoma skin cancer risk of never-users (1.44 to 2.83), and those who started at 20 or later 1.48 times (1.31 to 1.68). 3
Across 3 studies each, tanning indoors 10 or more times a year carried 1.56 times the non-melanoma skin cancer risk of never-users (1.31 to 1.86), against 1.32 times for fewer than 10 sessions a year (1.14 to 1.52). 3
First use of indoor tanning before age 20 carried 1.86 times the basal cell carcinoma risk of never-users (1.44 to 2.41) and 1.89 times the squamous cell carcinoma risk, on an interval of 0.90 to 3.98 that includes no difference. 3
Tanning indoors 10 or more times a year carried 1.46 times the basal cell carcinoma risk of never-users across 2 studies (1.28 to 1.66), and 1.65 times the squamous cell carcinoma risk across 2 studies (1.30 to 2.10). 3
Five cohort studies put the non-melanoma skin cancer risk of people who had ever tanned indoors at 1.48 times never-users' (1.18 to 1.84), and 13 case-control studies at 1.29 (0.97 to 1.72), which does not clear chance. 3
By melanoma type, 2 studies of superficial spreading melanoma gave indoor tanners 1.21 times never-users' risk (0.81 to 1.82) and 2 studies of nodular melanoma 1.03 (0.51 to 2.11); neither interval excludes no difference. 3
The pooled melanoma risk of indoor tanning was about the same in 15 studies published before 2000 (1.28, 1.09 to 1.50) and 21 published from 2000 on (1.26, 1.12 to 1.42). 3
The search found 484 records and kept 54 studies: 36 of melanoma and 18 of non-melanoma skin cancer, 9 of them on squamous and 10 on basal cell carcinoma. 3
Tanning indoors fewer than 10 times a year carried 1.46 times the squamous cell carcinoma risk of never-users across 2 studies (1.24 to 1.71). 3
In 65 Belgian women of skin type III who tanned regularly on commercial sunbeds, and in the sun, for 100 months, median skin extensibility rose 18.3 percent and hysteresis 113.1 percent. 19
In the same 65 sunbed users, median biologic elasticity of the skin fell 14.3 percent over the 100 months. 19
In these frequent sunbed users, mottled pigment spots began to spread after 1 to 3 years and stopped spreading after about 5 years. 19
After nine tanning-lamp sessions, the whole epidermis of 25 Leiden volunteers was 42 percent thicker. 20
The living layers of the epidermis thickened by 27 percent over the same tanning-lamp course, with no difference between lighter and darker skin (26 against 29 percent). 20
After the tanning-lamp course, skin brightness fell 11 percent on average, 13 percent in darker-skinned and 8 percent in lighter-skinned volunteers. 20
After the tanning-lamp course, the burn threshold of the 25 volunteers rose 3.78-fold in the lighter skin types and 4.19-fold in the darker ones, a significant difference. 20
After one slightly reddening tanning-lamp dose of 1.2 MED, p53 in the skin peaked at 24 hours, but in 3 of the 5 lighter-skinned volunteers it peaked at 48 hours. 20
The commercial tanning bed in the Michigan cell study delivered 135 W/m² of UVA and 1.7 W/m² of UVB to the culture flask. 17
Fourteen hours after equal UVA and UVB doses, human skin fibroblasts held 2.5 times their control level of glutathione after the tanning bed, significantly more than after a solar simulator. 17
Fourteen hours after the tanning-bed dose, heme oxygenase-1 activity in human skin fibroblasts was 2.1 times control, significantly higher than after the same dose from a solar simulator. 17
After the same UVA and UVB dose from a solar simulator, fibroblast glutathione rose only 0.5-fold and heme oxygenase-1 1.0-fold over control. 17
Forty-eight hours after equal doses, 79 percent of fibroblasts survived the tanning bed and 86 percent the solar simulator, a difference that was not significant; a tanning-bed dose followed by a simulator dose left 68 percent. 17
Among 266 people in a Montreal case-control study of squamous cell carcinoma, recalled use of a long-tube sunlamp carried a relative risk of 13.42, on an interval of 1.38 to 130.48. 22
In 5 healthy volunteers given nine whole-body sessions in a commercial solarium within 3 weeks, the mean enkephalin level in exposed skin almost doubled compared with the control level. 21
Plasma enkephalin, measured before, midway and at the end of the nine solarium sessions, rose consistently in 3 of the 5 volunteers. 21
In healthy volunteers, a single 2 MED dose of UVA from a lamp raised skin enkephalin about sixfold within 18 hours, while the same burn dose of UVB did not change it. 21
Psoriasis severity fell faster under the PUVA lamp than with psoralen plus sunlight: 43.92 against 29.13 percent at 2 weeks and 70.8 against 50.2 percent at 4 weeks (16 and 20 patients). 39
By the end point, mean psoriasis severity had fallen 86.85 percent with the PUVA lamp and 72.44 percent with psoralen plus sunlight, a difference that was not significant (P = 0.131). 39
The 15 responders on the PUVA lamp reached the end point in a mean 7.2 weeks and 21.4 sessions, against 9.3 weeks and 27.5 sessions for the 15 responders on psoralen plus sunlight. 39
PUVA-lamp patients made a median 26 hospital visits (range 14 to 39) during treatment, against 6 for patients on psoralen plus sunlight. 39
Counting both patient and hospital costs, a course of PUVA in a lamp cabinet cost a median US$62.7 per patient, against US$26.8 for psoralen plus sunlight. 39
Cost per patient per percent of psoriasis improvement was US$0.72 with the PUVA lamp and US$0.37 with psoralen plus sunlight. 39
The hospital's UVA chamber cost US$24,960 new, and a course of PUVA used a median 5.85 hours of machine time per patient. 39
Of 20 patients assessed in each group, 11 on the PUVA lamp developed hyperpigmentation against 3 on psoralen plus sunlight, and 3 on PUVA developed erythroderma against none. 39
Side effects of any kind affected 16 of 20 patients (80 percent) on the PUVA lamp and 12 of 20 (60 percent) on psoralen plus sunlight. 39
During 3 months of maintenance, 2 of 11 PUVA-lamp patients relapsed against 0 of 11 on psoralen plus sunlight, a difference that was not significant. 39
Of 59 psoriasis patients randomized, 23 were withdrawn or lost; in the PUVA group, 3 developed erythroderma and 1 severe phototoxicity and were withdrawn. 39
The median direct cost to patients of a PUVA course in the lamp cabinet was US$25.3, against US$12.4 for psoralen plus sunlight. 39
The hospital's median cost per patient was US$20 for PUVA in the lamp cabinet and US$4.1 for psoralen plus sunlight. 39
The cumulative narrowband UVB dose from the Waldmann UV 1002 cabinet ranged from 2.555 to 27.77 J/cm² per patient, given three times a week. 78
Scaling had stopped in 40 of the 44 narrowband UVB patients by the third visit and in the other 4 by the fourth. 78
With the gel applied before narrowband UVB, 42 of 44 patients (95.5 percent) reported no burning and 2 (4.5 percent) mild burning. 78
A 63-year-old Japanese man developed a basosquamous carcinoma on a leg that a mercury-quartz sunlamp had treated for a total of 30 sessions of 5 or 6 seconds over 3 years. 11
Of 3 Singapore patients with actinic prurigo given PUVA with a potent steroid, one stopped after 3 treatments, one was unchanged after 6 months, and one improved slightly. 79
Of 8 solar urticaria patients sent home to continue lamp treatment, 3 used the lamps regularly; the rest found it took too long with only four or six lamps at home. 80
In 2 of the 9 patients, tolerance built with fluorescent lamps fully prevented urticaria from natural sunlight. 80
In 113 patients in Bogotá, the median burn dose in a narrowband UVB phototherapy cabin was 390, 550, 770 and 885 mJ/cm² for skin types I to IV. 38
The Bogotá narrowband UVB phototherapy cabin delivered 4.3 mW/cm² at 15 cm. 38
In 100 people with facial or scalp actinic keratoses treated once on each side, conventional photodynamic therapy under a red lamp cleared 92.8 percent of mild lesions at 12 weeks, against 89.2 percent for daylight treatment. 40
On a 0 to 10 scale, pain averaged 5.7 on the side treated under the conventional lamp and 0.8 on the daylight side. 40
Over the whole trial, treatment-related adverse events affected 59 percent of subjects on the conventional-lamp side and 39 percent on the daylight side. 40
Phototoxic reactions were diagnosed on 10 conventional-lamp sides (10 percent) and 5 daylight sides (5 percent). 40
One week after treatment, investigators preferred the daylight side for local tolerability in 33.7 percent of subjects and the conventional-lamp side in 18.3 percent; 48 percent had no preference. 40
Of mild lesions that cleared by week 12, 96.6 percent on the conventional-lamp side and 96 percent on the daylight side were still clear at week 24. 40
In cultured human dermal fibroblasts, 250 kJ/m² of UVA killed 45 percent of cells, but only 15 percent after the cells had first been exposed to an infrared lamp (810 kJ/m²). 49
A UVB dose of 500 J/m² killed 75 percent of fibroblasts, but 45 percent of those pre-exposed to the infrared lamp. 49
Two infrared pre-exposures cut the fibroblast loss from 250 kJ/m² of UVA to 2 percent, and three abolished it. 49
The infrared lamp in the Paris study delivered 45 mW/cm² at the cells, and 30 minutes of it was not toxic. 49
In cells from a single donor, three infrared pre-exposures gave dose reduction factors of 2.15 against UVA and 2.6 against UVB. 49
Primary human skin fibroblasts given 860 J/cm² of infrared A from a lamp over 40 minutes changed the expression of 599 transcripts. 51
Per photon, blue light oxidized mitochondria in cultured human keratinocytes at 25 percent of the efficacy of UVA, and in mouse skin at 68 percent. 76
In live mouse skin, LEDs at 523, 623, 740 and 850 nm (green, red, far red and infrared) caused no mitochondrial oxidative stress, while the 460 nm blue LED did. 76
On the hands of 5 volunteers, 10 minutes of a blue LED set to the blue component of direct sunlight (11 mW/cm²) lowered flavin autofluorescence by about 8 percent on average. 76
Measured at the screen, a smartphone gave 0.0436 mW/cm² of 400 to 500 nm blue light, 1/251 of August sun in Yokohama (10.9 mW/cm²); at 10 cm it gave 0.0158 mW/cm², 1/693 of the sun. 75
A desktop computer screen gave 1/567 of the August sun's blue light at the screen and 1/637 at 10 cm; a laptop gave 1/566 and 1/768. 75
Blue light cut the viability of cultured human keratinocytes to 50 percent at 35 J/cm². 81
Infrared A light at 720 J/cm² left 10.61 percent of cultured human keratinocytes alive. 81
In full-thickness lab-grown human skin, blue light caused loss of dermal fibroblasts from 40 J/cm² and visible death of epidermal keratinocytes at 100 J/cm². 81
In the lab-grown skin, UVA at 30 to 40 J/cm² and blue light at 80 to 100 J/cm² raised IL-1α release to around 20 pg/mL. 81
A home-use IPL hair-removal device reddened 24 of 80 test sites on UV-tanned (facultatively pigmented) skin, against 7 of 80 on the same volunteers' untanned (constitutively pigmented) skin. 77
At the highest home-device setting of 10 J/cm², 15 of 20 tanned sites reddened against 5 of 20 untanned sites. 77
On tanned skin, the redness from the home IPL device appeared in 8 of 10 skin type IV volunteers, against 4 of 10 on their untanned skin. 77
No redness or other skin reaction from the home IPL device lasted to 1 hour after treatment or appeared at later visits. 77
Pain from the home IPL device on tanned skin ran from 0 to 10 (median 2), and on untanned skin from 0 to 8 (median 1), on a 0 to 10 scale. 77
On the tanned skin, median pain from the home IPL device rose with its setting: 1, 2 and 3 on a 0 to 10 scale at 7, 8 and 10 J/cm². 77
Before the home IPL test, 8 solar-simulator exposures totaling 25 standard erythema doses raised median skin pigmentation from 13.8 to 28.1 percent. 77
In 9 men kept in dim light, 6 mornings of a flat 0.1 lux control signal let the body clock drift later by at least 42 minutes (melatonin onset) despite fixed bedtimes. 70
The same 9 men showed no drift after 6 mornings of a simulated dawn averaging 155 lux: melatonin onset moved +10 minutes and temperature rhythm 0 minutes. 70
The dawn simulator's overhead halogen lamp ran from 0.001 to 1000 lux at the sleeper's head. 70