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A pinecone shaped gland 100-180 mg that lies between the superior colliculi at the base of the brain.
Has neuroglial stroma with photosensory and neuroendocrine cells, known as pineocytes.
The pineal gland is a small gland located posterior to the thalamus.
It produces the hormone melatonin.
Light striking the retina of the eyes sends signals to inhibit the function of the pineal gland.
In the dark, the pineal gland secretes melatonin, which has a sedative effect on the brain and helps to induce sleep.
This function of the pineal gland explains why darkness is sleep-inducing and light tends to disturb sleep.
Babies produce large amounts of melatonin, allowing them to sleep as long as 16 hours per day.
The pineal gland produces less melatonin as people age, resulting in difficulty sleeping during adulthood.