Updated 19 May 2013

Get your nightly dose of darkness

Too much artificial light at night may have negative health effects. The most recent research suggests a possible link with diabetes.


New research finds that diabetics have low levels of the hormone melatonin, which our bodies produce in darkness while we’re asleep.

Further investigation will be needed before scientists can tell if this means that low melatonin actually contributes to the development of diabetes. Nonetheless, the study adds to a body of evidence suggesting that melatonin suppression from excessive exposure to artificial light may have negative health effects.

Too much artificial light at night reduces production of the “sleep hormone" melatonin. It also disturbs the circadian rhythm (your body's internal clock that regulates the sleep-wake cycle), increases stress and suppresses the immune system.

The result may be raised risk for certain conditions. In addition to diabetes, these may include certain cancers (especially breast cancer, which has been the best studied so far in this regard), mood disorders, sleep disorders, obesity, heart disease and reproductive and developmental problems.

Much more work will need to be done before scientists understand this issue better. Nonetheless, concern is sufficient at this stage for the World Health Organisation to have added night-shift work to the “probably carcinogenic” list, and for sleep scientists to recommend that the night shift be limited to a maximum of two nights a week.

Even if you don't work the night shift, keep in mind that studying, partying or watching TV till the small hours also exposes you to lots of artificial light - an exposure unknown to our ancestors.

So, while research continues, turning in earlier is a good precautionary habit which also saves electricity. Make it your routine to get a full night's sleep in natural darkness, and rise with the sun. If you wake up during the night, aim to keep the lights off if possible. You can find sunrise times for your area on Weather24.

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