Circadian Clock

Articles tagged with "Circadian Clock".

Human Circadian Clock Runs 24.2 Hours: Why We Need Daily Light Reset

Tags: Circadian Clock, Human Pacemaker, Light Synchronization, Circadian Period

October 22, 2025

How Long Is the Human Internal Clock, and Why Does It Matter?

The human circadian pacemaker runs approximately 24.2 hours when isolated from external time cues, slightly longer than Earth’s 24-hour day. This precision research, conducted in controlled laboratory environments free from light and time cues, reveals why humans need daily light exposure to stay synchronized with the external world. Without this daily “reset” from bright light, our internal clocks would gradually drift later each day, explaining why maintaining proper light exposure is crucial for healthy sleep-wake cycles.

Light Timing Matters: How Single Bright Light Pulses Shift Your Circadian Clock

Tags: Light Timing, Circadian Clock, Phase Response Curve, Light Therapy

October 22, 2025

How Does the Timing of Light Exposure Affect Your Circadian Clock?

The timing of bright light exposure determines whether it advances or delays your circadian clock, following a predictable pattern called the phase response curve. Research shows that light exposure in the early morning (roughly 6 AM to noon) advances your circadian rhythm, making you wake up and go to sleep earlier, while light exposure in the evening (roughly 6 PM to midnight) delays your rhythm, making you stay up later and wake up later. Light exposure during the middle of the day has minimal effects on circadian timing, creating a “dead zone” where light doesn’t shift your biological clock.