by Susanna Perkins

Created on: July 21, 2009

Sleep. Shakespeare described "sleep that knits up the ravel'd sleave of care." Poet John Donne referred to it as "pain's easiest salve." Ogden Nash accused sleep of being as "perverse as human nature." Thomas Dekker, an English dramatist of the early 18th century, called it "the golden chain that ties health and our bodies together."

Now, in the early 21st century, scientists are finding out the extent of the connection between sleep and health. We've all experienced the occasional night without enough sleep due to stress, illness, or a new baby. Foggy thinking, irritability and clumsiness dog us through the next day. Occasional lack of sleep is not a problem for most of us, and sleeping well for one or two nights gets us back on track.

But what about the person who has a sleep disorder and does not sleep well, night after night over a lengthy period of time? Sleep deprivation (sleeping less than six hours per night) and short sleep (less than seven hours) have become pervasive in the US, and account for 100,000 "drowsy driving" auto accidents annually. The Exxon Valdez oil spill accident was attributed partially to sleep deprivation, as was the almost-meltdown at the Three Mile Island nuclear plant in Pennsylvania. Chronic sleep deprivation can cause high blood pressure, stroke, heart attack, hallucinations, depression or other mood disorders, and weight gain. Yes, weight gain.

Sleep deprivation causes weight gain in three distinct, but inter-related ways. It affects your appetite signaling and decreases your ability to burn stored fat, impairs your glucose metabolism, and lowers energy.

Your body is designed to store excess energy as fat, to be withdrawn from storage later as needed. Your hormones act as messengers, telling your body whether it needs to store more fat, or to burn fat to use as energy. When fat stores are sufficient, your fat cells release the hormone leptin into your blood. The leptin acts as an appetite suppressant. However, sleep deprivation lowers leptin levels and increases ghrelin, the hormone that signals hunger. Even if your body does not require energy, you feel hungry.

But the problem doesn't end there - if it did, we would just need a little will power. Unfortunately, insulin also plays a part. Most of us know insulin as the hormone that lowers blood sugar in diabetics, but that's just a byproduct of insulin's main job, which is storing excess energy.

Insulin pulls excess glucose out of the blood and stores it. The first storage

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