| Summary: | <p>Abstract</p> <p>Background</p> <p>A previous study reported a method for measuring the spectral transmittance of individual human eyelids. A prototype light mask using narrow-band “green” light (λ<sub>max</sub> = 527 nm) was used to deliver light through closed eyelids in two within-subjects studies. The first study investigated whether an individual-specific light dose could suppress melatonin by 40% through the closed eyelid without disrupting sleep. The light doses were delivered at three times during the night: 1) beginning (while subjects were awake), 2) middle (during rapid eye movement (REM) sleep), and 3) end (during non-REM sleep). The second study investigated whether two individual-specific light doses expected to suppress melatonin by 30% and 60% and delivered through subjects’ closed eyelids before the time of their predicted minimum core body temperature would phase delay the timing of their dim light melatonin onset (DLMO).</p> <p>Findings</p> <p>Compared to a dark control night, light delivered through eyelids suppressed melatonin by 36% (<it>p</it> = 0.01) after 60-minute light exposure at the beginning, 45% (<it>p</it> = 0.01) at the middle, and 56% (<it>p</it> < 0.0001) at the end of the night. In the second study, compared to a dark control night, melatonin was suppressed by 25% (<it>p</it> = 0.03) and by 45% (<it>p</it> = 0.009) and circadian phase, as measured by DLMO, was delayed by 17 minutes (<it>p</it> = 0.03) and 71 minutes (ns) after 60-minute exposures to light levels 1 and 2, respectively.</p> <p>Conclusions</p> <p>These studies demonstrate that individual-specific doses of light delivered through closed eyelids can suppress melatonin and phase shift DLMO and may be used to treat circadian sleep disorders.</p>
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