Sleeping well is good for health
We spend a third of our lives doing it.
Napoleon, Florence Nightingale and Margaret Thatcher got by on four hours a night. Thomas Edison claimed it was waste of time.
Why do we sleep?
This is a question that has baffled scientists for centuries and the answer is, no one is really sure. Some believe that sleep gives the body a chance to recuperate from the day's activities but in reality, the amount of energy saved by sleeping for even eight hours is miniscule - about 50 kCal, the same amount of energy in a piece of toast.
We have to sleep because it is essential to maintaining normal levels of cognitive skills such as speech, memory, innovative and flexible thinking. In other words, sleep plays a significant role in brain development.
What would happen if we didn't sleep?
A good way to understand the role of sleep is to look at what would happen if we didn't sleep. Lack of sleep has serious effects on our brain's ability to function. If you've ever pulled an all-nighter, you'll be familiar with the following after-effects: grumpiness, grogginess, irritability and forgetfulness. After just one night without sleep, concentration becomes more difficult and attention span shortens considerably.
With continued lack of sufficient sleep, the part of the brain that controls language, memory, planning and sense of time is severely affected, practically shutting down. In fact, 17 hours of sustained wakefulness leads to a decrease in performance equivalent to a blood alcohol level of 0.05% (two glasses of wine). This is the legal drink driving limit in the UK.
Research also shows that sleep-deprived individuals often have difficulty in responding to rapidly changing situations and making rational judgements. In real life situations, the consequences are grave and lack of sleep is said to have been be a contributory factor to a number of international disasters such as Exxon Valdez, Chernobyl, Three Mile Island and the Challenger shuttle explosion.
Sleep deprivation not only has a major impact on cognitive functioning but also on emotional and physical health. Disorders such as sleep apnoea which result in excessive daytime sleepiness have been linked to stress and high blood pressure. Research has also suggested that sleep loss may increase the risk of obesity because chemicals and hormones that play a key role in controlling appetite and weight gain are released during sleep.
How much sleep is required?
There is no set amount of time that everyone needs to sleep, since it varies from person to person. Results from a sleep profiler indicates that people like to sleep anywhere between 5 and 11 hours, with the average being 7.75 hours.
Jim Horne from Loughborough University's Sleep Research Centre has a simple answer though: "The amount of sleep we require is what we need not to be sleepy in the daytime."
For more info http://www.nhs.uk/Livewell/sleep/Pages/sleep-home.aspx