Our culture is obsessed with sleep, and the lack of it, yet many of us don't know some basic facts. As many as 35 million Americans experience chronic insomnia, and yet in 2006 only $20 million was spent on research. In the six years that author, professor and lifelong insomniac Gayle Green spent researching and writing her book "Insomniac". She learned almost all there is to know about sleep and the lack thereof. Here are five common myths about how we get our shut-eye and why:

1. Humans Need Eight Hours Sleep a Night

There are many ways of sleeping and few cultures sleep in eight-hour consolidated blocks like we do. Until the industrial era, many Western Europeans divided the night into "the first sleep" and "the second sleep". They'd go to bed soon after dark, sleep for four hours then wake for an hour or two during which they'd write, pray, smoke, have sex or even visit neighbors. In fact, there's some evidence to suggest that this sleep pattern may be the one most in tune with our inherent circadian rhythms.

2. Sleep Isn't Just a Bodily Function

Sleep is a biological, physiological system, akin to the cardiovascular system, the nervous system and so on. Like any other system, it is highly variable, and it wears out and gets more fragile with age.

3. Animals Don't Have Sleep Problems Insomnia occurs in animals and insects, too, sort of. Technically, insomnia is defined as a "complaint", and since animals can't complain, it's difficult to measure in them.

4. Falling Asleep Is a Gradual Process Nope Instead, for most people, it switches on and off like a light switch. But for insomniacs and narcoleptics, the switch doesn't work quite well. Instead they inhabit the space in between -- never entirely awake, nor entirely asleep.

5. Sleeping Less Burns More Calories

In the short term, yes, but sleeping less probably won't help you lose weight. Lack of sleep suppresses our natural appetite-depressants, while fueling appetite-increasers, often leading to weight gain.