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Sripathi Sonika Shruti

Pursuing Doctor of Pharmacy


12 June 2021

The most desperate and deprived thing every youngster needs is "SLEEP". With age as we grow we fight ourselves to get that proper 6-7 hours sleep. But did it cross our mind ever that, what actually is sleep? Why our body needs sleep? What happens when we sleep? Sleep is a healthy functioning of body which lets body and brain repair,restore and re-energize. Sleep reduces the muscular activity and increases brain function helping it memorise and restore all the information. Sleep is crucial for proper physical and mental health. It is as important as food and water to the body. The ability to react to stimuli is decreased and is different from wakefullness,but the person is more reactive than coma patient or disorder patient. Sleep occurs in cyclic rhythms repeating commonly after every 24hours. Sleep affects almost every tissue in the body. Sleep is a complex and dynamic process which effects the functioning of body.

Anatomy of sleep

The hypothalamus situated inside the brain,acts as control centres affecting sleep and arousal. Sleep-promoting cells within the hypothalamus and the brain stem produce a brain chemical called GABA, which acts to reduce the activity of arousal centres in the hypothalamus and brain stem. The pineal gland located inside the brain's two hemispheres, receives signals from the suprachiasmatic nucleus (SCN) and increase production of the hormone melatonin, which helps put you to sleep once the lights go down. The basal forebrain also promotes sleep and wakefulness, while part of midbrain acts as an arousal system. Release of adenosine from cells in basal forebrain support your sleep drive. Caffine counter acts sleepiness by blocking the actions of adenosine.

Physiology of sleep

The brain uses comparatively less energy during sleep then it does when awake. Sleep is divided into two broad categories : Rapid-eye-movement (REM) and Non-rapid-eye-movement (NREM). A person experiences all stages of NREM and REM sleep several times during night. NREM sleep occurs first which is followed by REM sleep.

NREM sleep has 3 stages, each lasts for about 5-15 minutes. A person undergoes all the three stages before reaching REM.

Stage 1 : Your eyes are closed, but its easy to wake you up. This phase last for 5-10 minutes.

Stage 2 : Your in light sleep. Your heart rates slow down and your body temperature falls down. This stage lasts for 10-25 minutes.

Stage 3 : The deep sleep stage. Its harder to rouse in this stage and if one wakes up, you would feel disoriented for some time. In this stage the body repairs and regrows tissues, builds bone and muscle and strengthens the immune system.

REM sleeps happens 90 minutes after you fall asleep. The first stage lasts for 10minutes and goes on increasing with time,the last stage lasts for an hour. REM is important because it stimulates the areas of brain that help with learning and is associated with increased production of proteins. You have dreams at this stage because your brain is highly active at this point.

Mechanism of sleep

The timings of sleep are controlled by the circadian clock (Process C) and sleep-wake homeostatis (Process S). Process C is a complex neurochemical system which uses signals from environment to recreate an internal day-night rhythm. The circadian rhythm influences the ideal timing of a restorative sleep episode. Sleepiness increases during the night. Modern humans find themselves desynchronized from their internal circadian clocks, due to requirement of work, long-distance travell,and more influence of indoor lightining. The more the organism is awake,the more they are deprived from sleep. This driver of sleep is referred to Process S. Process S is driven by the depletion of glycogen and accumulation of adenosine in the forebrain that disinhibits the ventrolateral preoptic nucleus, allowing for the inhibition of the ascending reticular activating system.

Time required to sleep

  • Newborn(0-3months) : 14 - 17 hours sleep

  • Infants(4-11 months) : 12 - 15 hours sleep

  • Toddlers(1-2years) : 11 - 14hours sleep

  • Preschoolers(3-4years) : 10 - 13hours sleep

  • School age children(5-12years) : 9 - 11hours sleep

  • Teenagers(13-17years) : 8 - 10 hours sleep

  • Adults(18-64years) : 7 - 9hours sleep

  • Older adults(65years and above) : 7 - 8hours sleep


Every individual dreams when they sleep.They may or maynot remember what they dreamt, but dreaming helps you process your emotions. People spend around two hours dreaming each night. They are mostly observed in the REM stage. People with mental stress or illnes maybe subjected to experience frightning dreams. Dreams tend to rapidly fade from memories after one wakes up, hence some people maintain dream journal.

Sleep health

Improper sleep can lead to many disorders which include insomniac,sleep apnea,restless leg syndrome,aging,cardiovascular diseases etc. In both children and adult short sleep increases risk of obesity and mental illness. Dietary and nutritional choices may affect sleep duration and quality. Diet rich in carbohydrates promotes good quality sleep compared to rich fats diet.

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