Turn off your screen to have a life free of serious troubles.

It is a good idea to switch off your (and your child’s) smartphone, laptop, and yes, tv, a few hours before going to sleep, if you want to keep away from insomnia, cardiovascular diseases, cancer and the sort!

More and more in our present time we use blue light emitters. Screens of laptop, smartphone, ipads, kindles and the kind, are strong emitters of blue light. Scientists agree in recognizing blue light as a strong inhibitor of melatonin. This is the sleep hormone that is produced in darkness (at normal and natural dimness of the night). Melatonin makes us sleepy and wanting to go to bed. At the crack of dawn, melatonin production stops and we want to get up and be active.

But, if we use artificial light late past darkness sets in, we mess up with our cycles. Stimulated by the blue rays of a screen or monitor, specific receptor cells in our retinas send a message to the pineal gland in the brain to stop producing melatonin and we want to keep awake.

This smells like a very realistic scenario, an issue many families are probably facing, wondering if buying the smartphone or the tablet to their child was a good idea after all. At the University of Florence in Italy it was found that when children were deprived of TV, computers and video games, their melatonin production increased by an average 30%. In a different experiment, when volunteers were reading from an iPad for 4 hours, melatonin secretion was delayed by an hour and a half.

So continuously exposing oneself to electrical lighting (any, but especially the blue band of screens) in the late evening disrupts melatonin production and could therefore potentially impact sleep, but also thermoregulation, blood pressure, glucose metabolism and more. We get sleepless nights, we feel tired in the morning, as if we crossed the planet in an aircraft overnight. But there is worse....

Melatonin is not only a sleep hormone but it has numerous effects on the functioning of many tissues and on our overall health. Most of its mechanisms of actions are still unknown. It is a powerful antioxidant with a particular role in protecting the DNA. As a free radical scavenger, it helps fight inflammation and can strengthen the immune system. Some researchers also believe that melatonin levels may be related to aging. Melatonin is also implicated in the blood flow to the brain and in the general blood circulation, in the control the timing and release of female reproductive hormones and the start of puberty, in the functioning of the kidneys, pancreas, fat tissue and the brain itself.

Therefore the lack of melatonin can lead to minor but also more serious illnesses. For example, disruptions in the age of puberty have been found to be related to tv watching and laptop use. And more important, links have been repetitively found between lack of melatonin and cancer, heart disease and diabetes. This has been tested, studied and claimed by several scientific researches suggesting especially a real link between light-at-night and cancer, particularly breast cancer but also prostate and colon. One of the most direct evidence comes from studying shift workers who showed to have the highest rates of breast cancers, as well as from experimental studies run on mice. The evidence regarding shift work and breast cancer is so strong that in 2007 the World Health Organization categorised shift work as a probable cause of cancer.

Therefore, melatonin is medically used to treat insomnia, but also cancer (breast and prostate), fibromyalgia, irritable bowel syndrome, multiple sclerosis, epilepsies and neurodenegerative disorders like Alzheimer’s. Dr Karatsoreos thinks that a particular study proofs “that disrupting the clock by changing the light cycle can result in changes in the brain, behaviour and physiology".

Apart from visible light, certain non-visible ultraviolet wavelengths and extremely low frequency electric and magnetic fields may influence melatonin rythms (Olcese, 1990; Reiter, 1992).

Normal home electric light and even dim light may be disruptive to human physiology by supressing melatonin. But low-energy fluorescent bulbs and LED-based lighting are the worst, producing much more blue light than the old-fashioned tungsten light bulbs. There are now new low energy-lights, called ESL, that have a spectrum more similar to, and an energy consumption 70% less than, that of the old incandescent bulbs.

Changing light bulbs is relatively easy. The hard part will be persuading people (and children especially) to turn off their TVs and iPads well before they go to sleep.

Alternatively, there remains the option of wearing goggles that filter the blue light out! By wearing them in the house before going to bed (even watching tv or Ipads) they prevent blocking production of melatonin by filtering out blue wavelengths.

You might look like a character out of a 70s sci-fiction movie, but you might protect yourself from insomnia and cancer!


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Kostoglou-Athanassiou, I. 2013. Therapeutic Applications of Melatonin. Ther Adv in Endo and Metab. 2013;4(1):13-24.

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Wikipedia, 2015. Electron-stimulated luminescence. https://en.wikipedia.org/wiki/Electron-stimulated_luminescence

Wikipedia, 2015. Melatonin, in: https://en.wikipedia.org/wiki/Melatonin#Immune_system

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