Blocking Short-Wavelength Component of the Visible Light Emitted by Smartphones’ Screens Improves Human Sleep Quality

Abstract

Background: It has been shown that short-wavelength blue component of the visible light spectrum can alter the circadian rhythm and suppress the level of melatonin hormone. The short-wavelength light emitted by smartphones’ screens can affect the sleep quality of the people who use these devices at night through suppression of melatonin.Objectives: In this study, we examined the effects of covering the screens of smartphones with different filters (changing the effective wavelength of the light) on sleep delay time in 43 healthy students.Materials and Methods: Volunteer students were asked to go to bed at 23:00 and to use their mobile phones in bed for watching a natural life documentary movie for 60 minutes. No filter was used for one night while amber and blue filters were used for other 2 nights. Photospectrometry method was used to determine the output spectrum of the light passing through the filters used for covering the screens of the mobile phones. The order for utilizing amber or blue filters or using no filter was selected randomly. After 1 hour, the participants were asked to record their sleep delay time measured by a modified form of sleep time record sheet.Results: The mean sleep delay time for the “no-filter” night was 20.84±9.15 minutes, while the sleep delay times for the nights with amber and blue filters were 15.26±1.04 and 26.33±1.59 minutes, respectively.Conclusion: The findings obtained in this study support this hypothesis that blue light possibly suppresses the secretion of melatonin more than the longer wavelengths of the visible light spectrum. Using amber filter in this study significantly improved the sleep quality. Altogether, these findings lead us to this conclusion that blocking the short-wavelength component of the light emitted by smartphones’ screens improves human sleep.

Relationship Between Sedentary Behaviors and Sleep Duration in University Students from Five ASEAN Countries

“…It could be assumed that university students in this study mainly used sedentary behavior time as screenbased sedentary time (internet use and smartphone use and possibly television watching, which was not independently assessed in this study). Several mechanisms have been proposed for explaining the link between increased screen time and short or long sleep, e.g., the emission of blue light from screens possibly suppresses the secretion of melatonin and delays sleep onset and the interaction with social media may stimulate the wake system (26,27).…”

Neuronal Responses to Short Wavelength Light Deficiency in the Rat Subcortical Visual System

“…Due to melanopsin’s substantial contribution to all NIF functions the most widely used filters are cut off/bandwidth filters and amber lenses/goggles that remove short wavelengths from polychromatic/visible light ( Rahman et al, 2008 , 2017 ; Wren et al, 2014 ; Gladanac et al, 2019 ). Interestingly, these approaches of filtering have also been successfully exploited in minimizing disruptive effects of night time light exposure on circadian rhythms, quality of sleep and cognitive performance in humans ( Gringras et al, 2015 ; Ayaki et al, 2016 ; Ostrin et al, 2017 ; Mortazavi et al, 2018 ; Kazemi et al, 2019 ; Domagalik et al, 2020 ). However, until now an unanswered question remains: how do similar changes in the spectral composition of light influence neuronal activity in retinorecipient brain structures?…”

The Association Between Smartphone Use and Breast Cancer Risk Among Taiwanese Women: A Case–Control Study [Response to Letter]

“…We agree with his opinion in terms of blue light suppressing the secretion of melatonin, which possibly causes circadian rhythm disruption. 2 Though most applications are available in modern smartphones, people are mostly not aware of the dangers of the blue light, hence they usually do not apply the blue light filter for protection, especially in Taiwan and China. 3 That is why we did not consider this factor would affect our result.…”