Evening light environments can be designed to consolidate and increase the duration of REM-sleep

Abstract

Evening exposure to short-wavelength light has disruptive effects on circadian rhythms and sleep. These effects can be mitigated by blocking short-wavelength (blue) frequencies, which has led to the development of evening blue-depleted light environments (BDLEs). We have previously reported that residing 5 days in an evening BDLE, compared with residing in a normal indoor light environment of similar photopic lux, advances circadian rhythms and increases the duration of rapid eye movement (REM) sleep in a randomized cross-over trial with twelve healthy participants. The current study extends these findings by testing whether residing in the evening BDLE affects the consolidation and microstructure of REM sleep in the same sample. Evening BDLE significantly reduces the fragmentation of REM sleep (p = 0.0003), and REM sleep microarousals in (p = 0.0493) without significantly changing REM density or the latency to first REM sleep episode. Moreover, the increased accumulation of REM sleep is not at the expense of NREM stage 3 sleep. BDLE further has a unique effect on REM sleep fragmentation (p = 0.0479) over and above that of circadian rhythms phase-shift, indicating a non-circadian effect of BDLE. If these effects can be replicated in clinical populations, this may have a therapeutic potential in disorders characterized by fragmented REM sleep.

Clinical benefits of modifying the evening light environment in an acute psychiatric unit: A single-centre, two-arm, parallel-group, pragmatic effectiveness randomised controlled trial

“…We have previously shown that the same light environment as employed in the current RCT produced changes in sleep, circadian rhythms, and arousal in healthy young adults. 17,18 Further, there were no negative effects in that population, nor in nurses’ ability to work in the blue-depleted LE at the present unit, 41 or elsewhere. 42 However, it is possible that aspects of the ‘dosage’ we employed is suboptimal.…”

“…Our own research has shown that changing the evening light environment in an acute psychiatric unit has positive effects on the circadian, sleep and neurocognitive systems of healthy young adult volunteers. 17,18 However, it is unknown whether any change would translate into better clinical outcomes. Several mental health inpatient projects are underway, but there is limited research on the potential benefits of exposing trans-diagnostic inpatient populations to dynamic, programmable lighting conditions.…”

Effects of Different Nocturnal Lighting Stimuli on Melatonin, Sleep and Cognitive Performance of Workers in Confined Spaces

“…There was no significant difference in sleep time, time to fall asleep, the proportion of deep and light sleep, proportion of REM eye movement, etc. Thus, more sophisticated equipment (such as Polysomnography (PSG)) should be used to conduct experiments with a larger sample size in subsequent studies, since low proportional blue light exposure would prolong REM sleep and advance the DLMO phase while also increasing overall sleep time [68]. While lighting in the evening can suppress melatonin secretion and delay circadian phase, the patterning of light exposure across the day and evening can have moderating effects [69].…”

Circadian therapy interventions for glymphatic dysfunction in concussions injuries: A narrative review

“…Evening blue light restriction has proven effective in promoting circadian normalization. 70 In clinical studies, blue-blocking glasses improve subjective sleep quality, 71 reduce sleep onset latency, 72 and normalize melatonin levels. 73 To the best of our knowledge, blue-blocking glasses have not been studied as an adjuvant treatment for acute concussion.…”