Geen licht op de slaapkamer tegen kanker*
Uit twee studies blijkt de hoeveelheid licht voor en tijdens het slapen heel belangrijk is. Iedere vorm van licht tijdens het slapen zorgt voor het verstoren van het slaap-waakritme en verandert het delen van lichaamscellen. Deze verstoring in de celdeling is kenmerkend voor het ontstaan van kanker. Reeds
na 1 uur blootstelling aan licht tijdens het slapen is deze verstoring te meten. Uit de andere kleine studie, onder 116 gezonde jong volwassenen blijkt dat blootstelling aan licht tussen zonsondergang en het naar bed gaan de slaapkwaliteit duidelijk kan veranderen. De hoeveelheid licht in deze periode beïnvloed de aanmaak van melatonine, een hormoon dat invloed heeft op het slaap-waakritme, de bloeddruk en bloedsuikerwaarden. Veel licht in deze periode verkort de tijd van melatonineproductie wel met 90 minuten in vergelijking tot dimlicht in deze periode.
Shut off the light at night to reduce cancer risk
A wealth of research is pointing to an ever increasing problem that is shown to increase our risk of cancer. The problem is with light sources in the bedroom at night when most people are asleep. Many of the critical biological functions carried out by our body during sleep are dependent on circadian rhythms and are disturbed by the smallest amount of light from devices such as iPods, laptops, electronic readers and television. Information provided by the journal Cancer Genetics and Cytogenetics shines a light on the importance of sleeping in a totally dark room to lower cancer risk.
Researchers have been able to show that a single light emission during sleep is enough to disrupt the circadian rhythm of the sleep cycle and alter normal cellular division. The body requires 7 to 9 hours of uninterrupted sleep with no light distraction each night to complete the repair and regeneration functions essential to maintain optimal
health.
The study author, Dr. Ben-Shlomo noted "damage to cell division is characteristic of cancer, and it is therefore important to understand the causes of this damage." Changes in gene expression were identified after exposure to artificial light for a period of one hour during normal sleep hours. The cellular `biological clock` was altered and normal gene transcription and repair processes were harmed.
This research clearly provides proof that minimal exposure to an artificial light source is sufficient to alter the expression of genes that are connected to the formation of cancer as well as of genes that assist in the fight against cancer. Alteration of genetic expression is a precursor to cancer initiation, and disruption of nighttime circadian rhythm with a light source can be a trigger for carcinogenesis.
The Journal of Clinical Endocrinology & Metabolism reports that exposure to electrical light sources between dusk and bedtime disrupts the physiological processes that are regulated by the hormone melatonin. This affects sleepiness, thermoregulation, blood pressure and glucose homeostasis, all essential for healthy cellular repair and maintenance functions.
Melatonin secretion controls the normal sleep-wake cycle in the body and influences blood pressure, body temperature and insulin sensitivity. Levels of the hormone begin to increase 30 minutes before bedtime. Researchers found that exposing test participants to dim light for 8 hours before bedtime delayed the release of melatonin by 90 minutes. Exposure to room light during sleep cut production of the hormone by half.
When melatonin production is delayed or halted by artificial light sources, our nighttime rhythms are disturbed and normal metabolic activity required for cellular repair are disrupted. Lead study researcher, Dr. Joshua Gooley of Harvard Medical School commented, "Our study shows that this exposure to indoor light has a strong suppressive effect on the hormone melatonin. This could, in turn, have effects on sleep quality and the body`s ability to regulate body temperature, blood pressure and glucose
levels."
The numbers of artificial light-producing electrical gadgets that are part of our daily life have exploded over the past decade. Many people keep these devices in close proximity during night hours and are continually exposed to light emissions that influence melatonin production. Melatonin dysfunction increases the health risks associated with high blood pressure, temperature regulation, and insulin resistance. Dim all artificial light sources in preparation for bed and sleep in a totally dark room to lower cancer risk and to maximize the rejuvenating effect of a good night sleep.
(April 2011)
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