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What happens when you miss your sleep?

IT MIGHT have been worth staying up for, but the next day we usually feel the consequences - we're tired, grumpy and have difficulty concentrating. And why?

Because we're sleep-deprived. Studies have revealed that effects range from weight loss and irritability to an increase in accidents and even attempted suicides. STEPHANIE ZINSER explains . . .

SLEEP is one of the most popular research topics in psychology, yet there are still few definitive answers about this mysterious daily period of inactivity.

Professor Chris Idzikowski, chairman of the Royal Society Of Medicine's Forum On Sleep and director of the Sleep Assessment And Advisory Service, says: 'I still don't think we really know why we need sleep.' There are two theories. First, we sleep in order to conserve energy, because even though our brain activity remains high during sleep, our physical activity is kept at a minimum.

Body temperature is lowered by one to two degrees celsius when we sleep, so our metabolic rate consequently drops by 20pc.

Second, sleep is a chance for the brain to reorganise the memory and the body to repair itself.

There are two basic types of sleep: rapid eye movement (REM or 'dreaming') sleep and non-REM sleep, and during the night our brains follow cycles of sleep.

Each cycle begins with non-REM sleep: stages one, two, three and four, which are characterised by different patterns of brain waves. Then, these stages quickly reverse and end in REM sleep, which is the dreaming period.

Each of these complete cycles lasts between 90 and 100 minutes - but, as the night continues, there is generally less 'deep' sleep (non-REM stages three and four) and more dreaming (REM) sleep.

Our bodies behave differently during REM and non-REM sleep. During non-REM sleep, the heart rate lowers, breathing slows, muscles relax and blood flows more easily through the body. Melatonin, the sleep-

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inducing hormone, and growth and thyroid hormones are also released.

During REM sleep, there is an increase in brain activity and temperature, the eyes move rapidly, muscles twitch, and blood pressure and heart and breathing rates start showing rapid variations.

While many parts of the body can rest while we are awake but relaxing, some parts of the brain's cerebral cortex seem unable to do so.

Even when we lie relaxed but awake in a darkened and silent room, sections of the cerebrum stay in a state of 'quiet readiness', prepared to respond immediately. The only time these areas appear to rest is during deep sleep.

Interestingly, the symptoms we suffer when we're sleep-deprived seem to relate to the functions of the cerebral cortex - namely concentration, speech, memory, and flexible and inventive thinking.

However, people differ in the amount of sleep they need.

Scientists Albert Einstein and Thomas Edison had widely differing sleep habits. Edison is claimed to have dismissed sleep as a 'waste of time', although he took naps during the day. Einstein, on the other hand, said he needed ten hours' sleep every night.

THE extremes are even more interesting - in 1965 a 17-year-old American, Randy Gardner, stayed awake continuously for 11 days and 12 minutes, although he suffered from lack of coordination and concentration, hallucinations, blurred vision, slurred speech and memory lapses.

In 1980, Californian Robert McDonald reportedly stayed awake for a record 18 days, 21 hours and 40 minutes.

Professor Idzikowski says: 'Concentration and memory are among the first functions to suffer when we're lacking sleep. Irritability increases and unintended sleep is the biggest danger.' Indeed, drivers who fall asleep at the wheel through lack of sleep may trigger at least 1,500 accidents every year in America.

James Maas, Professor of Psychology at Cornell University, New York, believes that many people are constantly running a two-hour sleep deficit.

'Just an extra hour or two causes huge rebounds in happiness, productivity and creativity,' he says.

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Reference: http://www.thefreelibrary.com/What+happens+when+you+miss+your+sleep%3F-a0109609743

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