Key facts
- An internal ~24-hour biological clock.
- Strongly influenced by light exposure.
- Governs sleep timing, hormones, and alertness.
- Consistent routines keep it aligned.
Your circadian rhythm is an internal clock running on roughly a 24-hour cycle, coordinating when you feel sleepy or alert, when hormones like melatonin and cortisol rise and fall, and even when you tend to perform best physically. Light is its main signal — morning light wakes the system up, and darkness cues it toward sleep.
Keeping this rhythm aligned supports better sleep, energy, and recovery. Regular sleep and wake times, morning daylight exposure, and limiting bright light at night all help. Disrupting it — through irregular schedules, late screens, or shift work — degrades sleep quality and can leave you tired and under-recovered.
Frequently asked questions
How do I keep my circadian rhythm healthy?
Keep consistent sleep and wake times, get bright light (ideally daylight) in the morning, and limit bright or blue light in the evening to support melatonin and sleep.
Does the circadian rhythm affect training performance?
Yes. Alertness, body temperature, and strength tend to follow a daily pattern, and many people perform best in the late afternoon — though consistency matters more than timing.
Get the app