Sleep is regarded physiologically as absence of alertness and wakefulness. The biological clock/ circadian rhythm or the central pace maker which is located at the supra chiasmatic nuclei in the hypothalamus regulates diurnal variation of physiological functions of the body. The wand that regulates this variation is melatonin (the hormone from pineal gland).
Sleep is defined as a reversible period of oblivion with minimum alertness and is essential to mankind (also animals). Alternatively sleep has also been defined as a state of consciousness that is different from alert wakefulness by a loss of critical reactivity to event stimuli in the environment. Scientists now agree that sleep is not passive or inactivity rather it involves the active reorganisation of the brain. Despite a great amount of research is done on sleep there remain grey areas in this field.
The normal sleep pattern consists of six to eight cycles of sleep that transcends from light sleep to deep sleep. Sleep is characterised into two types, Non Rapid Eye Movement (NREM) sleep and rapid eye movement sleep (REM) sleep.
Lack of sleep leads to poor concentration, motor in coordination, attention deficit, irritability, restlessness, raised blood pressure and heart rate etc.
Last date updated on June, 2014