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Sensitivity of the human circadian pacemaker to nocturnal light: melatonin phase resetting and suppression
How night-time light affects the body's internal clock by changing melatonin timing and levels
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Abstract
Ocular exposure to light during the early biological night can significantly advance the human circadian pacemaker.
- Light exposure has a non-linear relationship with its intensity in influencing the circadian pacemaker.
- The study involved 23 healthy young volunteers and examined a single light exposure lasting 6.5 hours.
- Both the phase-delaying effects of light and its suppressive effects on plasma melatonin follow a logistic dose-response curve.
- Approximately 1% of the light intensity of bright light (around 9000 lux) can elicit half of the maximal phase-delaying response.
- Dim room light (approximately 100 lux) can significantly affect plasma melatonin levels and the timing of the circadian rhythm.
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