Having done a little research on melatonin I think this useful hormone may be another small thing to consider when trying to live a healthy, natural lifestyle.
Melatonin is secreted into the blood by the pineal gland in the brain. It is a natural anti-oxidant, helping to protect DNA and plays a big role in our sleep cycles helping us to get quality sleep and make us sleepy at night. What's important is the way our brain makes melatonin. When our eyes are exposed to light (specifically blue wavelengths), our production of melatonin is inhibited. This makes sense because if it wasn't for artificial light then we'd be producing sleep inducing melatonin after the sun goes down. Our modern way of living exposes us to light sources that wouldn't have been there during our millions of years of evolution meaning that we're not producing the amounts of melatonin that we naturally should be. Everyone living a LFRV lifestyle is interested in giving the body what it needs but we should also consider the things that we subject our bodies to that aren't so natural. For instance sitting in front of a bright computer screen is a major source of artificial light that can inhibit melatonin production. Bright lights in rooms at night and watching TV will also surpress melatonin production.
This may all seem a tad anal but if it can help at all in being as healthy as you can then whats the harm in dimming the lights a bit or using romantic candles instead of 100watt bulbs. You even save electricity too!
By the way if you're like me and like to use your computer then I found this handy little free program which cuts out blue light from your computer screen at night! http://www.stereopsis.com/flux/