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Showing posts from April, 2014

Melatonin

In humans, melatonin is produced by the pineal gland, a small endocrine gland located in the center of the brain but outside the blood–brain barrier. The melatonin signal forms part of the system that regulates the sleep–wake cycle by chemically causing drowsiness and lowering the body temperature, but it is the central nervous system (specifically the suprachiasmatic nuclei, or SCN) that controls the daily cycle in most components of the paracrine and endocrine systemsrather than the melatonin signal (as was once postulated).

Infants' melatonin levels become regular in about the third month after birth, with the highest levels measured between midnight and 8:00 AM.

In humans, 90% of melatonin is cleared in a single passage through the liver, a small amount is excreted in urine, and a small amount is found in saliva.

Human melatonin production decreases as a person ages. Also, as children become teenagers, the nightly schedule of melatonin release is delayed, leading to later slee…