As stated before, the specific function of sleep is not known. There are many theories that have been researched that will be highlighted. Some scientists refer to sleep as “the major stress buster” in our lives.
It is inevitable that sleep plays an important function in our lives. People who do not sleep are more prone to various disorders ranging from growth disorders in children, psychiatric disorders, autoimmune disorders, blood disorders, cardiac disorders and decrease in wound healing.
• Function of NREM Sleep (about 50 % of total sleep time in infants and 75-80% of total sleep time in adults)
During NREM sleep all physiological states of the body decreases including breathing, brain waves (brain functioning),blood pressure due to “vasodilatation”; i.e. relaxation of vessels; caused by to the reduced sympathetic activity and possibly accumulation of adenosine, heart rates and body temperature which is related to the decrease of the “basal metabolic rate”. The cerebral blood flow also falls by 10–20% in NREM sleep compared to wakefulness.
Amazingly due to these physiological changes, the blood pressure may decrease shortly after sleep 5-15% of the normal wake range.
Given this knowledge scientists are convinced that NREM sleep acts as a cardio protective mechanism. Yet in the incidence of coronary artery diseases (diseases related to arteries supplying the heart) scientists believe that sleep aggravates ischemia (decreased blood supply) which in turn may cause cardiac infarctions (tissue death).
• Function of REM sleep (about 50 % of total sleep time in infants and 20-25% of total sleep time in adults)
1- Hormone synthesis
2- Re-energizing the body
• Hormone synthesis
In REM stage, many hormones are produced by the body of which the most important early in human life is the growth hormone. This is denoted by the increased sleep durations in infancy. In other words, infants and children who do not sleep well do not grow well.