Science
How do circadian rhythms work?
Circadian rhythms are your body's internal 24-hour clock. A region of the brain tracks light and dark and releases hormones — like melatonin at night — to control sleep, alertness, temperature, and more, keeping your body in sync with the day.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how circadian rhythms works.
Step by step
- 1It's the body's roughly 24-hour internal clock.
- 2The brain uses light cues to keep time.
- 3Hormones like melatonin signal sleep and wake.
- 4It governs sleep, alertness, and body temperature.
Frequently asked questions
- How do circadian rhythms work?
- A brain clock tracks light and releases hormones to time sleep, alertness, and other daily body cycles.
- What controls our circadian rhythm?
- A brain region (the suprachiasmatic nucleus) syncing to light, which adjusts hormones like melatonin.
- Why does jet lag happen?
- Travel shifts your day faster than your internal clock can adjust, leaving rhythms out of sync.