Suprachiasmatic Nucleus (SCN)

Definition

The suprachiasmatic nucleus (SCN) is a tiny region in the brain located in the hypothalamus, directly above the optic chiasm. It controls circadian rhythms.

Analogy

The SCN is like a master clockmaker who sets all other clocks. It receives light information from your eyes and adjusts your internal 'clock' accordingly so you feel awake during daylight hours and sleepy when it gets dark.

Related terms

Melatonin: A hormone produced by pineal gland that helps regulate sleep-wake cycles. Its production increases with darkness and decreases with light exposure, under control of SCN.

Hypothalamus: A part of brain involved in many functions including hormone production, regulation of body temperature, hunger, moods etc., which also houses SCN.

Optic Chiasm: The point in the brain where the optic nerves from each eye meet and partially cross over. It's crucial for binocular vision and also transmits light information to SCN.