Introduction
Sleep is the natural state of bodily rest observed in mammals, birds, many reptiles, amphibians and fishes. It is equally a state of unconsciousness from which a person or animals can be aroused. In this state the brain is relatively more responsive to internal than external stimuli. In contrast, coma is also a state of unconsciousness from which a person or animals cannot be aroused (Max, 2006). Sleep is homeostatic; therefore it is controlled by the body’s internal balance (Max 2006). It is considered critical for maintenance of health, support of life, restoration of body and brain functions and promotion of neural-immune interaction (Aurell and Elqvist, 1985; Everson et al., 1989). These are reflected in the roles of sleep in the brain for memory co-ordination and teaching (Turner et al., 2007). Through its role in hormone activities such as in growth hormone, thyroid stimulating hormone and prolactin to mention a few, metabolic processes are properly co-coordinated and carbohydrate storages are carried out (Bonnet and Arand, 2003; Everson and Read, 1995).
Sleep deprivation, a general lack of necessary amount of sleep, which may occur as a result of sleep disorder or deliberate inducement or torture, is deleterious to health when it is prolonged. It has been scientifically observed that prolonged sleep deprivation may result in aching muscles, blurred vision, and clinical depression, and constipation, dark circles under the eyes, daytime drowsiness, and decrease mental activity and concentration, delirium, dizziness, fainting, hallucination, hand tremor, headache, hypertension, irritability, loss of appetite, memory lapses or loss, nausea, nystagmus, pallor, psychosis-like symptoms, severely yawning, sleep paralysis while awake, slowed reaction time, slowed wound healing, synaesthesia, temper tantrum in children, weakened immune system, weight loss, diabetes mellitus type II, obesity without weight gain and death (Gotlieb et al., 2005).
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