The pineal gland
Pineal gland · glandula pinealis
A pine-cone-shaped gland deep in the brain that releases melatonin at night.
What it does
The pineal gland sits near the centre of the brain. When it gets dark, signals that start in the eyes reach it, and it releases melatonin, a hormone that tells the body it is night and helps set the timing of sleep.
Surprising fact
The philosopher René Descartes called the pineal gland the "principal seat of the soul", partly because it is a single structure rather than a pair.
Why it matters
Bright screens in the evening can delay melatonin release, which is one reason late-night phone use can make it harder to fall asleep.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.