Restricting short‐wavelength light in the evening to improve sleep in recreational athletes – A pilot study

Abstract

Sleep is crucial for recovery and skill acquisition in athletes. Paradoxically, athletes often encounter difficulties initiating and maintaining sleep, while having sufficient sleep opportunity. Blue (short-wavelength) light as emitted by electronic screens is considered a potential sleep thief, as it suppresses habitual melatonin secretion. The current study sought to investigate whether blocking short-wavelength light in the evening can improve sleep onset latency and potentially other sleep parameters among recreational athletes. The study had a within-subject crossover design. Fifteen recreational athletes, aged between 18 and 32 years (12 females, 3 males), were randomly assigned to start the intervention period with either the light restriction condition (LR; amber-lens glasses), or the no-light restriction condition (nLR; transparent glasses). Sleep hygiene practices, actigraphy and diary-based sleep estimates were monitored during four consecutive nights within each condition. Sleep hygiene practices did not significantly differ between conditions. Results indicate that blocking short-wavelength light in the evening, as compared to habitual light exposure, significantly shortened subjective sleep onset latency (Δ = 7 min), improved sleep quality (Δ = 0.6; scale 1-10), and increased alertness the following morning. Actigraphy-based sleep estimates showed no significant differences between conditions. Blocking short-wavelength light in the evening by means of amber-lens glasses is a cost-efficient and promising means to improve subjective sleep estimates among recreational athletes in their habitual home environment. The relatively small effects of the current study may be strengthened by additionally increasing morning-and daytime light exposure and, potentially, by reducing the alerting effects of media use before bedtime.

Circadian Rhythm Dysregulation and Restoration: The Role of Melatonin

“…Specifically, the human circadian pacemaker in the SCN is more sensitive to short or blue wavelength light (460 nm) than to long or red wavelength light (555 nm), as the short wavelength has been shown to suppress melatonin [24][25][26]. Intensity of the light also has a negative effect on sleep, but of lesser magnitude than wavelength of light [27]. Alternatively, limiting short-wavelength light exposure has been shown to significantly shorten sleep onset latency by 7 min, improve sleep quality, and increase alertness the following morning [28].…”

Impacts of home lighting on human health

“…Other studies found that using such devices before bedtime, for example for social interaction, may affect sleep quality but without necessarily reducing melatonin levels. 140,141 In recent years, several sets of metrics have been proposed for lighting that supports circadian entrainment. These are based on measures at eye level weighted against the spectral sensitivity of the melanopsin-containing ipRGCs.…”

“…Other studies found that using such devices before bedtime, for example for social interaction, may affect sleep quality but without necessarily reducing melatonin levels. 140,141…”

Dim light, sleep tight, and wake up bright – Sleep optimization in athletes by means of light regulation

“…Furthermore, while positive effects have been observed in clinical populations that suffered from pathology-related sleep problems (e.g. Alzheimer's disease, delayed/advanced sleep phase disorder, sleep onset insomnia), effects of light regulation on the sleep of young and healthy individuals such as athletes, remain largely unknown (cf., Knufinke, Fittkau-Koch, Møst, Kompier, & Nieuwenhuys, 2019).…”