Hormonal
Gradual advancement of the sleep-wake schedule combined with moderate indoor light exposure (90-150 lux) fails to advance the circadian phase and significantly reduces the amplitude of the melatonin rhythm.
If you are trying to shift your sleep schedule (e.g., for shift work or jet lag), relying on normal indoor lighting (like office or home lights) will not reset your body clock and may actually weaken your melatonin rhythm. To successfully shift your circadian phase, you likely need exposure to much brighter light (e.g., >10,000 lux) timed specifically relative to your body's temperature nadir, or you must accept a period of reduced circadian amplitude.
After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed... The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54% (17–94%)...
Why this rating
Randomized controlled trial with parallel groups, rigorous constant routine assessment, and clear statistical significance.
Source
Amplitude Reduction and Phase Shifts of Melatonin, Cortisol and Other Circadian Rhythms after a Gradual Advance of Sleep and Light Exposure in Humans
Derk‐Jan Dijk et al. · PLoS ONE · 2012
DOI 10.1371/journal.pone.0030037
More from this paper
- Bright light exposure (>10,000 lux) timed to follow the core body temperature minimum successfully advances the circadian phase of melatonin and cortisol by approximately 8-10 hours.Good
- Reduction in melatonin amplitude caused by circadian misalignment correlates with reductions in the amplitude of core body temperature, cortisol, and alertness rhythms.Moderate
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