Get psyched!

HOW BIO­CHEM­I­CAL PRO­CESSES KEEPS YOU IN SYNC.

TechLife Australia - - WELCOME - [ TECHLIFE TEAM ]

OUR BOD­IES RUN on an in-built 24-hour clock em­bed­ded in a part of the brain called the suprachi­as­matic nu­cleus (SCN). Its 20,000 nerve cells sit in the mid­dle of the brain above the back of the eyes and on top of a struc­ture called the hy­po­thal­a­mus. These are the body’s mas­ter time­keep­ers, set­ting the rhythm for sleeping, wak­ing, eat­ing and hor­mone re­lease.

Even in a test tube, cells from the SCN keep time. They are stuffed with mol­e­cules called tran­scrip­tion fac­tors, which change the pro­duc­tion lev­els of other mol­e­cules on a 24-hour cy­cle. The mas­ter reg­u­la­tors are known as BMAL and CLOCK. To­gether, these two mol­e­cules ac­ti­vate the pro­duc­tion of mol­e­cules called pe­ri­ods and cryp­tochromes. As lev­els of pe­ri­ods and cryp­tochromes rise, they feed back to BMAL and CLOCK, switch­ing pro­duc­tion off again. This causes the amount of these mol­e­cules to go up and down in cy­cles, form­ing the ba­sis for a pre­cise time­keeper.

Like any clock, the SCN can run fast or slow, so the time is re­set, or en­trained, ev­ery day by day­light. This is done by light-sen­si­tive cells in the back of the eye known as in­trin­si­cally pho­to­sen­si­tive reti­nal gan­glion cells. They don’t pro­duce im­ages when they de­tect light: in­stead, they send sig­nals to the SCN via a bun­dle of nerve tis­sue called the retino­hy­potha­la­mic tract, sync­ing the mas­ter clock, which in turn mes­sages the rest of the body about the time.

AS TIME BE­TWEEN MEALS PASSES, THE AMOUNT OF GLU­COSE AVAIL­ABLE TO THE BRAIN DE­CREASES, TRIG­GER­ING THE RE­LEASE OF STRESS HOR­MONES...

The chem­i­cal struc­ture of mela­tonin, a sleep hor­mone made by the pineal gland.

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