Get a nightly dose of darkness

Excess artifical light at night may raise risk for certain cancers.

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 cancers, notably breast cancer and possibly prostate cancer too.

Sleep scientists recommend that night shift work should 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 excessive amounts of artificial light.

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.

- Olivia Rose-Innes, EnviroHealth Editor, Health24, June 2012