The body releases melatonin as part of the processes that support the circadian rhythm.
The hypothalamus is a small area at the base of the brain near the pituitary gland. This area contains the suprachiasmatic nucleus (SCN), which is the primary regulator of the circadian rhythm.
The SCN maintains this rhythm in response to changing sunlight levels in each 24-hour period. At dawn, for example, it stimulates the release of various hormones that prepare the body for waking.
When the sun sets and light levels begin to decrease, the SCN prepares the body for sleep by signaling the pineal gland to release melatonin.
Some people refer to melatonin as the “hormone of darkness” because the pineal gland releases it in the evening. Exposure to light inhibits this process.
Melatonin affects numerous bodily functions, such as:
- blood pressure
- immune function
- bone formation
If a child’s pineal gland does not secrete enough melatonin at night, they may develop insomnia or delayed sleep phase disorder. This condition extends wakefulness at nighttime, even when a person feels tired, and it often appears during teenage years.
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