Nucleus
Hypothalamus
An almond-sized control center for temperature, hunger, thirst, sleep and hormones.
The hypothalamus is small, about the size of an almond, but it is the brain's main keeper of balance inside the body. It watches your temperature, water, energy and hormone levels and nudges them back when they drift, much like a thermostat. It drives basic urges like hunger, thirst and sleep, and it controls the pituitary gland to steer hormones throughout the body. It also holds the body's master clock, the suprachiasmatic nucleus.
Where it is
At the base of the brain, just below the thalamus and directly above the pituitary gland, with the spot where the optic nerves cross tucked under its front edge.
What it does
Body thermostat
It senses your body temperature and triggers sweating or shivering to keep you close to 37 °C (98.6 °F).
Hunger and thirst
It tracks your energy and water levels and creates the urge to eat or drink when you run low.
Master clock
Its suprachiasmatic nucleus keeps a roughly 24-hour rhythm and resets it each day using light from your eyes.
Hormone command
It tells the pituitary gland which hormones to release, and it makes oxytocin and vasopressin itself.
Stress and fight-or-flight
It helps control heart rate, blood pressure and the stress response through nerves and hormones.
Think of it as a smart home control panel that runs the heating, the fridge alerts and the day-night lighting all at once.
Works with
- Pituitary glandHangs right below it on a stalk and carries out its hormone orders.
- Optic chiasmSits just below its master clock, which gets light signals directly from the eyes.
- AmygdalaSends it fear and stress signals, triggering racing heart and stress hormones.
- BrainstemCarries out its commands for heart rate, breathing and digestion.
- Mammillary bodiesTwo small bumps at its back end that are part of the memory circuit.
- Neurosecretory cellIts special nerve cells that release hormones straight into the blood.
When it goes wrong
Diabetes insipidus
If it makes too little vasopressin, the kidneys cannot hold on to water. People pass large amounts of pale urine and feel very thirsty.
Narcolepsy
Loss of a small group of cells here that make orexin (also called hypocretin) causes one type of narcolepsy, with sudden sleep attacks during the day.
Tumors or injury
Damage here can cause extreme hunger or weight changes, trouble controlling body temperature, or hormone problems.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- A fever is your hypothalamus deliberately turning up its thermostat to help fight an infection. That is why you shiver while your temperature climbs.
- Oxytocin and vasopressin are made here, not in the pituitary. The pituitary just stores them and releases them into the blood.
- The master clock is named for its spot: "supra" means above and "chiasm" means crossing, because it sits right above where the optic nerves cross.
By the numbers
Where the name comes from
From Greek "hypo" (under) plus thalamus: the part "under the inner chamber", because it sits just below the thalamus.
Learn it in a lesson
- Emotion and rewardFear, drive and the value of things. A short guided lesson in 3D.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the hypothalamus?
Show the answer
Body thermostat. It senses your body temperature and triggers sweating or shivering to keep you close to 37 °C (98.6 °F).
Body thermostat. It senses your body temperature and triggers sweating or shivering to keep you close to 37 °C (98.6 °F).
The hypothalamus is part of which larger structure?
Show the answer
Diencephalon. It belongs to the diencephalon.
Diencephalon. It belongs to the diencephalon.
Which part fits this description? "Like a smart home control panel that runs the heating, the fridge alerts and the day-night lighting all at once."
Show the answer
Hypothalamus. It is the hypothalamus. An almond-sized control center for temperature, hunger, thirst, sleep and hormones.
Hypothalamus. It is the hypothalamus. An almond-sized control center for temperature, hunger, thirst, sleep and hormones.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Hypothalamus, StatPearls, NCBI Bookshelf
- Neuroanatomy, Nucleus Suprachiasmatic, StatPearls, NCBI Bookshelf
- The forebrain, Queensland Brain Institute, University of Queensland
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Explore the hypothalamus in 3D
Turn it around, zoom inside and see how it connects to the rest of the brain, then test yourself with quick quizzes.
Open it in 3D