Functions and Control of Sleep

Abstract

Human beings spend about one-third of the life time in sleep. The studies in the past few decades have led us into a deeper understanding of the crucial and complex functions and control of sleep in human beings and other animals. Whether this complex process confers an evolutionary advantage of these higher living organisms in the presence of the day and night cycle on earth, or it simply evolves as a necessity of maintaining the living state in these organisms remains a mystery to us. The observation that a single cell organism can survive for sufficiently long enough without the highly organized process in higher living organisms involving all the neurons, neurotransmitters, and cytokines, has proven that, at least, sleep is not a basic necessity universally required for all living organisms to survive.