Obesity Articles

Are our light bulbs making our children fat?

Are our light bulbs making our children fat?

Are our light bulbs making our children fat?


Richard L. Hansler PhD


At first it might seem ridiculous that a light bulb could have the ability to make anyone fat or skinny. There is however, considerable evidence to support that idea. For example, it is known that people who sleep less than 7 hours a night are more likely to be obese. They are exposed to light for longer than average. People who work night shift are more likely to be obese than people who work during the day. Night shift workers are exposed to light for longer than day workers.


The link between light, darkness and obesity is most likely the hormone of darkness, melatonin. If in darkness for along enough time, the human body can produce melatonin for 11 or 12 hours. However, exposing the eyes to light during the time when melatonin should be flowing will delay the flow and reduce the amount produced. Bright light can completely eliminate it.


Several recent studies looked at the ways the body gets rid of fat. One way is to convert it to heat. In one study they looked at how melatonin stimulated this process and in another found that stimulating rats to convert fat to heat raised their body temperature 0.4 C. In another study they found that rats fed a high-fat diet gained excess weight. However, if given melatonin along with the high-fat diet, they did not gain extra weight. Yet another study found that rats raised under continuous light (so they did not produce melatonin) developed fatty tissue while rats reared under normal light dark conditions (so they made melatonin) did not.


And it’s not just light bulbs we need to be concerned about. TV and computer screens also put out light. Young children tend to set close to the TV. Now, with the super-bright, large, wide screens the problem is even worse.


But there is a way out of this problem without sending our kids to bed in the dark at 7 P.M. In 2001 two research groups, one in the US and one in the UK, both made an important discovery. Our eyes have special sensors different from the rods and cones. These sensors don’t produce vision; they control our body clock that controls melatonin. These sensors are most sensitive to the blue end of the visible spectrum. By using light bulbs that don’t produce the blue rays we can make melatonin just as if we were in darkness.


In 2005 these low blue light bulbs, eyeglasses that block the blue and filters for TV screens became available on the internet. It’s not just the children we need to be concerned about. Obesity affects people of all ages.


On the positive side, thousands of people have found they fall asleep more easily and sleep better by maximizing melatonin by avoiding blue light in the hours before bedtime. There’s also substantial evidence that maximizing melatonin reduces the risk of cancer, especially breast cancer and prostate cancer.


For more information visit www.lowbluelights.com or call 216 397 1657.

New Light on Avoiding Obesity

Tan DX, Manchester LC, Fuentes-Broto L, Paredes SD, Reiter RJ.

Department of Cellular and Structural Biology, the University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.


Summary A worldwide increase in the incidence of obesity indicates the unsuccessful battle against this disorder. Obesity and the associated health problems urgently require effective strategies of treatment. The new discovery that a substantial amount of functional brown adipose tissue (BAT) is retained in adult humans provides a potential target for treatment of human obesity. BAT is active metabolically and disposes of extra energy via generation of heat through uncoupling oxidative phosphorylation in mitochondria. The physiology of BAT is readily regulated by melatonin, which not only increases recruitment of brown adipocytes but also elevates their metabolic activity in mammals. It is speculated that the hypertrophic effect and functional activation of BAT induced by melatonin may likely apply to the human. Thus, melatonin, a naturally occurring substance with no reported toxicity, may serve as a novel approach for treatment of obesity. Conversely, because of the availability of artificial light sources, excessive light exposure after darkness onset in modern societies should be considered a potential contributory factor to human obesity as light at night dramatically reduces endogenous melatonin production. In the current article, the potential associations of melatonin, BAT, obesity and the medical implications are discussed.

PMID: 20557470 [PubMed – as supplied by publisher]


Ref. 2

Neurosci. 2001 Aug 15;21(16):6405-12.

Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor.

Brainard GC, Hanifin JP, Greeson JM, Byrne B, Glickman G, Gerner E, Rollag MD.

Collaborators (1)

Brainard GC.

Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA. george.brainard@mail.tju.edu


The photopigment in the human eye that transduces light for circadian and neuroendocrine regulation, is unknown. The aim of this study was to establish an action spectrum for light-induced melatonin suppression that could help elucidate the ocular photoreceptor system for regulating the human pineal gland. Subjects (37 females, 35 males, mean age of 24.5 +/- 0.3 years) were healthy and had normal color vision. Full-field, monochromatic light exposures took place between 2:00 and 3:30 A.M. while subjects` pupils were dilated. Blood samples collected before and after light exposures were quantified for melatonin. Each subject was tested with at least seven different irradiances of one wavelength with a minimum of 1 week between each nighttime exposure. Nighttime melatonin suppression tests (n = 627) were completed with wavelengths from 420 to 600 nm. The data were fit to eight univariant, sigmoidal fluence-response curves (R(2) = 0.81-0.95). The action spectrum constructed from these data fit an opsin template (R(2) = 0.91), which identifies 446-477 nm as the most potent wavelength region providing circadian input for regulating melatonin secretion. The results suggest that, in humans, a single photopigment may be primarily responsible for melatonin suppression, and its peak absorbance appears to be distinct from that of rod and cone cell photopigments for vision. The data also suggest that this new photopigment is retinaldehyde based. These findings suggest that there is a novel opsin photopigment in the human eye that mediates circadian photoreception.

PMID: 11487664 [PubMed – indexed for MEDLINE]Free Article

Ref. 3

J Clin Endocrinol Metab. 2005 May;90(5):2755-61. Epub 2005 Feb 15.

Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect on performance during simulated shift work.

Kayumov L, Casper RF, Hawa RJ, Perelman B, Chung SA, Sokalsky S, Shapiro CM.

Sleep Research Laboratory, Department of Psychiatry, University Health Network, ECW 3D-035, 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8. lkayumov@uhnres.utoronto.ca


Decreases in melatonin production in human and animals are known to be caused by environmental lighting, especially short-wavelength lighting (between 470 and 525 nm). We investigated the novel hypothesis that the use of goggles with selective exclusion of all wavelengths less than 530 nm could prevent the suppression of melatonin in bright-light conditions during a simulated shift-work experiment. Salivary melatonin levels were measured under dim (<5 lux), bright (800 lux), and filtered (800 lux) light at hourly intervals between 2000 and 0800 h in 11 healthy young males and eight females (mean age, 24.7 +/- 4.6 yr). The measurements were performed during three nonconsecutive nights over a 2-wk period. Subjective sleepiness was measured by self-report scales, whereas objective performance was assessed with the Continuous Performance Test. All subjects demonstrated preserved melatonin levels in filtered light similar to their dim-light secretion profile. Unfiltered bright light drastically suppressed melatonin production. Normalization of endogenous melatonin production while wearing goggles did not impair measures of performance, subjective sleepiness, or alertness.