Evening and night exposure to screens of media devices and its association with subjectively perceived sleep: Should "light hygiene" be given more attention?
Abstract
Objective: The aim of the study was to examine subjective sleep quality in a population of healthy volunteers and its association with evening and night light exposure to screens of media devices. Methods: A total of 693 participants (mean age 31.2+-11.4 years, 159 men, and 538 women) completed an online questionnaire battery consisting of several sleep-related questionnaires: PSQI, FSS, MCTQ, MEQ, and added questions assessing the timing and character the evening and night exposure to electronical devices (TV, PC, tablets, and phones), and the use of various filters blocking short-wavelength light.
Results: Statistical analyses show that longer cumulative exposure to screen light in the evening was associated with greater sleep inertia in the morning (p=0.019, η2=0.141) and longer sleep latency on workdays (p=0.038, η2=0.135). Furthermore, exposure to screen light 1.5 h before sleep or during night awakenings was also associated with a decreased chance to wake up before alarm clock (p=0.003, d=0.30), larger social jet lag (p<0.001, d=0.15), more daytime dysfunction (p<0.001, d=0.40), decreased subjective sleep quality (p=0.024, d=0.16), and more fatigue (p<0.001, d=0.52).
A statistical trend for an increase in duration of sleep on weekdays (p=0.058, d=0.23) was also found in participants using blue-light filters in the evening hours. Discussion: Our results are in line with other studies that converge to show the negative association of evening and night exposure to short-wavelength light on subjective and objective sleep parameters.
Results suggest that light hygiene in general population should be given more attention not only in the context of clinical sleep medicine but also in the realm of public health.