Individually tailored light intervention through closed eyelids to promote circadian alignment and sleep health

Abstract

Background Light is most effective at changing the timing of the circadian clock when applied close to the core body temperature minimum. The present study investigated, in a home setting, if individually tailored light treatment using flashing blue light delivered through closed eyelids during the early part of the sleep period delayed circadian phase and sleep in a population of healthy older adults and in those suffering from early awakening insomnia. Methods Twenty-eight participants (9 early awakening insomniacs) completed an 8-week, within-subjects study. Twice, participants collected data during two baseline weeks and one intervention week. During the intervention week, participants wore a flashing blue (active) or a flashing red (control) light mask during sleep. Light was expected to delay circadian phase. Saliva samples for dim light melatonin onset (DLMO) were collected at the end of each baseline and intervention week. Wrist actigraphy and Daysimeter, a calibrated light and activity meter, data were collected during the entire study. Results Compared to baseline, flashing blue light, but not flashing red light, significantly (p<0.05) delayed DLMO. The mean ± standard deviation phase shift (minutes) was 0:06 ± 0:30 for the flashing red light and 0:34 ± 0:30 for the flashing blue light. Compared to Day 1, sleep start times were significantly delayed (by approximately 46 minutes) at Day 7 after the flashing blue light. The light intervention did not affect sleep efficiency. Conclusions The present study demonstrated the feasibility of using light through closed eyelids during sleep for promoting circadian alignment and sleep health.

<p>Effects of red light on sleep inertia</p>

“…Except for 3 participants in the D condition, all other participants in all 3 conditions had sleep efficiency >80%, and all but 2 participants in the RM condition had sleep efficiency >90%. These results are consistent with our previously published studies,36–38 where PSG measurements, collected during the first 90 mins of sleep, did not reveal any significant effect of light exposure from the light mask on sleep duration and quality. Future studies should employ an objective measure of sleep to reaffirm our previous findings that the quality and quantity of sleep are not affected while sleeping with the red light mask.…”

Intermittent Light Exposures in Humans: A Case for Dual Entrainment in the Treatment of Alzheimer's Disease

“…Following the laboratory and field studies confirming their hypothesis, Figueiro ( 112 ) tested the effectiveness of the flashing blue light on delaying the circadian system of those with early sleep onset living in their homes. They recruited 28 subjects (9 early awakening insomniacs) to participate in an 8-week, placebo-controlled, within subjects, crossover study.…”

“…This study was followed by another study where the impact of the flashing blue lights was tested in a laboratory setting and a follow-up study conducted in the field, where exposures to light outside the intervention were measured using a calibrated personal device, but not controlled (111). In the laboratory study, they exposed 11 subjects to the flashing blue light delivered to close eyelids for 1 h in the early part of the night.…”

Delayed sleep phase disorder: clinical perspective with a focus on light therapy

“…Following the laboratory study, Figueiro 87 collected field data from 28 participants (nine early awakening insomniacs) in an 8-week, within-subjects study. Twice, participants collected data during 2 baseline weeks and 1 intervention week.…”