A growing body of scientific evidence has shown that the human body's need for sleep has to be adequately fulfilled in order to ensure survival.
Unfortunately in the modern world, many folk do not get enough sleep due to a variety of reasons - such as domestic and work demands, social responsibilities, medical conditions or unhealthy lifestyles.
Sleep is the period that the brain requires so it can be restored to its normal function - because the human brain has not been engineered to work round the clock. Regular sleeping time is needed to regenerate certain parts of the body, especially the brain, so that it may continue to function optimally.
A good analogy from modern technology is to consider sleep to be the period when the body's batteries are recharged - or when the hard drive of the brain is defragmented.
How Much Sleep do Humans Need?
As to the fundamental question of how much sleep people need for good physical health and to be able to function safely, views in the past have varied. Recent carefully controlled experiments on healthy adult volunteers have revealed that when sleep was repeatedly restricted to less than seven hours per night, this resulted in significant cognitive dysfunction (for example reduced working memory, impaired vigilance and lowered attention span).
Current views are that the average adult needs a minimum of seven hours sleep per day. Restricting sleep to less than this amount of time can cause a host of neurobehavioural deficits including depressed mood and lapses of attention. Why sleep deprivation causes these problems, however, is not clear.
Impairment of Temporal Lobe Function
Sleep has been shown to be important for processing memories and newly learned tasks. In a research study done during verbal learning tests on subjects after they were fully rested, functional MRI scans of their temporal lobes (the part of the brain that is associated with processing of language) showed that this area of the cerebrum was very active. In subjects who had been deprived of sleep, however, similar MRI scans showed no such activity within the temporal lobes.
Physiological Effects of Sleep Restriction
Research studies done by subjecting healthy adult volunteers to sleep deprivation have also demonstrated that sleep restriction produces physiological consequences that may be unhealthy. The abnormal alterations in body function that result from short-term sleep restriction include impaired glucose tolerance, raised blood pressure and abnormal activation of the sympathetic nervous system. Although the measured physiologic changes demonstrated in these short-term studies were small, they showed the likely mechanisms through which continued sleep restriction may affect health in the long term.
So the take home message is that human beings need a minimum period of sleep each day - time when their brain cells can rest, regenerate, recover and return to optimal function on the following day.
Reference:
Banks S, Dinges DF. Behavioral and Physiological Consequences of Sleep Restriction (2007) J Clin Sleep Med. 2007 August 15; 3(5): 519–528
Sanjiva Wijesinha - Dr. Sanjiva Wijesinha, Associate Professor at Monash University medical school, writes on health, travel and medical topics.
