Sleep Patterns and Bio-Clock Every living being on the earth is blessed with resting time known as sleep. Every animal has its own sleeping patterns. Humans are not kept apart. Every human is born with an in-built clock to regulate the sleep patterns known as bio-clock. The bio clock has 24.3 hours cycle. The primary circadian clock in mammals is located in the hypothalamus, within suprachiasmatic nucleus (SCN) made up of a pair of distinct groups of cells. Any abnormality or damage to the SCN causes the disturbance in sleep-wake patterns. The retina in the eye acts as an information source of illumination for the SCN. Apart from rods and cones (classical photo receptors in the eye), retina also contains specialized ganglion cells, which are specified to send information on illumination directly to SCN, for regulating the master circadian rhythms.
The ganglion cells contain a photo pigment known as melanopsin which passes the signals through retinohypothalamic pathway to SCN. The SCN interprets the duration of day and night from the information received from the signals from these cells, passes it to the pineal gland. In response to the given inputs, the pineal gland secretes the hormone 'melatonin'. Presence of this melatonin provides information about night length, and the melatonin levels are peak in the night and fade off during the day.
There are peripheral clocks in the vital organs like skin, liver, lungs, esophagus, pancreas, spleen, thymus etc... And they have their own oscillatory systems to regulate their clocks. It is the bio clock that orders the body to rest. However there is also relation to our body temperature as well as hormonal influences. People get sleep when the body temperature goes down. There is also influence of melatonin. Melatonin is a dark hormone produced by the body at night. We can say that with the orders of bio clock, body produces melatonin, which also lowers the body temperature getting us to sleep. Disturbed bio-clock: If the circadian rhythms are disrupted for any reason such as journey between time zones, conditions like bipolar disorder, sleep disorders, drugs like cocaine; they have negative impact on health. People may experience simple conditions like jet lag, fatigue, disorientation and insomnia to serious problems like seasonal affective disorder (SAD), delayed sleep phase syndrome (DSPS), Bipolar disorder and Sleep disorders. In addition, a reversal that is observed in the sleep-wake cycle may be a sign or complication of uremia, azotemia or acute renal failure. Take care of bio clock by maintaining a regular sleep patterns to stay healthy.
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