About author :
Suvarna*, Dr. Hindustan Abdul Ahad
B. Pharmacy, Balaji College of Pharmacy, Anantapur, AP, India
E-mail: [email protected]
Sleep is a naturally recurring state of relatively suspended sensory and motor activity, characterized by total or partial unconsciousness and the inactivity of nearly all voluntary muscles.
KEY WORDS: sleep, stages, circadian clock
STAGES OF SLEEP:
Rapid eye movement (REM)
Non-rapid eye movement (NREM or non-REM) sleep.
N1, N2, N3
Sleep proceeds in cycles of REM and NREM, the order normally being N1 → N2 → N3 → N2 → REM. Sleep stages and other characteristics of sleep are commonly assessed by polysomnography.
Sleep timing is controlled by the circadian clock. The circadian clock is an inner timekeeping, temperature-fluctuating, enzyme-controlling device which works in tandem with adenosine.
Sleep per day varies with age and condition of a person. Viz., in Newborn (up to 18 hours), 1–12 months ( 14–18 hours), 1–3 years (12–15 hours), 3–5 years (11–13 hours), 5–12 years (9–11 hours), Adolescents (9–10 hours), Elderly and Adults (7–8 hours)
FUNCTIONS OF SLEEP:
Wound healing has been shown to be affected by sleep. The metabolic phase during sleep is anabolic; anabolic hormones such as growth hormones are secreted preferentially during sleep which plays an important role in growth of human being.
REM sleep appears to be important for development of the brain. REM-induced muscle inhibition in the presence of brain activation exists to allow for brain development by activating the synapses.
Memory seems to be affected differently by certain stages of sleep such as REM and slow-wave sleep (SWS). The direct current stimulation greatly enhances word-pair retention giving evidence that SWS plays a large role in the consolidation of episodic memories.
Sleep minimizes energy expenditure.
Dreaming is the perceived experience of sensory images and sounds during sleep, in a sequence which the dreamer usually perceives more as an apparent participant than as an observer. Dreaming is stimulated by the pons and mostly occurs during the REM phase of sleep.
PROBLEMS OF INSUFFICIENT SLEEP:
It is a sleep disorder characterized by having too little sleep.
It is a symptom which can accompany several sleep, medical and psychiatric disorders, characterized by persistent difficulty falling asleep and/or difficulty staying asleep.
Transient insomnia – lasts for less than a week.
Acute insomnia – lasts for a period of less than a month.
Chronic insomnia – lasts for longer than a month.
The god blessed sleep has many advantages which refreshes the mankind.