Posted on Mon, 7 Sep 09
A good night’s sleep may cut your cancer risk. Sound like a good excuse for an early night? Actually it is, low levels of a hormone produced while sleeping called melatonin may significantly increase your risk of developing various cancers, in particular breast cancer (1).
Our hormones are subject to natural rhythms that pay attention to the cycle of day and night, including the "sleep hormone" melatonin. Switching on electric lights in the evening, when we should be sleeping, tricks our body into thinking its daytime, our natural rhythm is disrupted and melatonin production switches off (2). Fortunately there are ways to restore our natural rhythm and switch melatonin production back on.
Stop polluting the night sky
Melatonin is produced in the brain by the pineal gland in response to the natural pattern of day and night, dark and light. Minimising “light pollution,” or over exposure to artificial lighting, is the best way to encourage natural melatonin production. Avoiding staying up late, shift work, and the night time glow of brightly lit urban areas may boost melatonin levels. Long distance flights also disrupt melatonin production, resulting in jet lag, however this may be more due to high exposure to solar radiation in the plane cabin than exposure to artificial light (3).
Enjoy a sunrise
Some strategies that may also be effective melatonin boosters are putting on some amber glasses, eating popcorn and watching the sunrise, not necessarily in that order. Exposing our eyes to bright early morning light helps restore melatonin levels, a strategy that has been shown to be effective for reducing the effects of jet lag (4).
The rationale for sporting a pair of amber glasses, preferably in the hours before bed, lays in the ability of amber glass to block blue light wavelengths, the type of light that suppresses melatonin production during daylight hours (5).
While there is less evidence to support a hot bowl of popcorn it has been recently discovered that almost all plant foods including vegetables, fruits, and especially grains such as rice, corn and oats contain plant melatonin (phytomelatonin), which may have important health benefits (6). The role of phytomelatonin in human nutrition is only just beginning to be explored but eating plenty of plant foods, preferably a wide variety of vegetables and not popcorn, is certainly an important cancer prevention strategy.
1. Schernhammer ES, Hankinson SE. Urinary melatonin levels and postmenopausal breast cancer risk in the nurses’ health study cohort. Cancer Epidemiol Biomarkers Prev 2009;18(1):74–9.
2. Stevens RG, Davis S. The melatonin hypothesis: electric power and breast cancer. Environ Health Perspect. 1996 Mar;104 Suppl 1:135-40.
3. Bartsch C, Bartsch H. The anti-tumor activity of pineal melatonin and cancer enhancing life styles in industrialized societies. Cancer Causes Control (2006) 17:559–571
4. Burgess HJ, Crowley SJ, Gazda CJ, Fogg LF, Eastman CI. Preflight adjustment to eastward travel: 3 days of advancing sleep with and without morning bright light. J Biol Rhythms. 2003 Aug;18(4):318-28.
5. Alpert M, Carome E, Kubulins V, Hansler R. Nighttime use of special spectacles or light bulbs that block blue light may reduce the risk of cancer. Med Hypotheses. 2009 Sep;73(3):324-5.
6. Reiter RJ, Tan DX, Manchester LC, Simopoulos AP, Maldonado MD, Flores LJ, Terron MP. Melatonin in edible plants (phytomelatonin): Identification, concentrations, bioavailability and proposed functions. World Rev Nutr Diet. 2007;97:211-30.