Sleep mechanism and primary function

Abstract

Why we sleep? There is no clear answer to this Question. By the way we can look at this question from another perspective: why do we wake up and maintain wakefulness for a long time? We need wakefulness to obtain food and water, avoid danger, reproduction and lot of vital and social needing. Sleep is opposite towards of wakefulness. Sleep is a complex process and all the functions have not been clear yet (probably that’ why it is named as mysteries of biology. Although it is necessary for human brain and body activities. Also, it has a main role in protection and survival.

Many researchers showed that the prolonged wakefulness and lack of adequate sleep lead to many diseases such as Diabetes, Obesity and Cardiovascular disease. Sleep plays an important role to form a new pathway and processing information in the memory, clear out toxins from brain, promote growth, support immune system, regulation many hormones which finally helps to maintain homeostasis. Sleep time is varying in people and it depends on Genetics, environment and lifestyle, but each sleep cycle includes 90- 110 minutes and the number of cycles is different among people. Sleep has two parts: NREM (non-rapid eye movement or Slow waves sleep) and REM (rapid eye movement or Fast waves, or paradoxical sleep).

The first one has 4 stages and during NREM the coordination between neurons become much stronger, while body activities, blood pressure and heart beats are decreased and in this stage if we saw dreams we cannot remember them, while REM sleep, that by electroencephalographic records looks like wakefulness (that’s why known as paradoxical sleep characterized by increasing of heart and breathing rate, is rich of emotionally colored and memorizing dreams, inhibition of the spinal cord motor neurons.According to Stickgold, “When we dream, we get the pieces. When we wake, we can know the whole “