by Elaine Sihera

Created on: November 09, 2009   Last Updated: November 12, 2009

Sleep is essential to the healthy functioning of our bodies, especially for general body repair and restoration. After a hard day's activity, sleep seems crucial for rejuvenating our bodies for the next day. Without adequate amounts of sleep, we tend to feel irritable, tired and listless. Thus sleep is very good for our health, especially if we can manage eight hours, on average.

In fact, what many people do not often realise is that a lack of sleep-especially on a regular basis-is associated with long-term health consequences, not just diabetes, particularly high blood pressure, and heart disease. These conditions, in turn, may lead to a shortened life expectancy.

Scientists have recently discovered that people who sleep less than six hours each night appear to have a higher risk of developing' impaired fasting glucose' - a condition that can precede type 2 diabetes (when the body makes in too much insulin but isn't able to use it efficiently, thus becoming insulin resistant). Population studies have shown that diabetes rates rise as sleep declines. Tests repeatedly proved that people who slept less than six hours, on average were more prone to having type 2 diabetes.

So how are the two factors connected?

Human bodies have a clock, an internal rhythm that dictates when we fall asleep and when we get up. They are the 'molecular timekeepers, made and degraded every 24 hours', that set this daily cycle. When any part of this ticking clock is faulty, sleep schedules gradually change. Sleep-deprived subjects, seem to crave starchy, sweet foods, they exhibit insulin resistance and do not regulate their blood sugar well. Combined, these tend to lead to obesity which also predisposes diabetes in a vicious circle.

Investigations by three international teams of researchers have suggested that rising diabetes and falling sleep are linked by a protein that senses the 'sleep-inducing hormone, melatonin', which is the regulator of the body's sleep clock. Melatonin is closely linked to increased glucose levels and diabetes. Best known for its sleep-inducing properties, melatonin levels in the body are tied to daylight: when the lights go down, melatonin levels rise and drowsiness soon follows. When daylight occurs, the level drops and we no longer feel sleepy.

The scientific experiments also revealed how the melatonin directly interact with insulin-producing cells. The melatonin 'receptor' was thought to be expressed in the brain - where the body's master clock resides.

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