Investigating the Combined Effect of Artificial Light at Night and Noise on Sleep Quality of High School Students

Adolescents frequently use smartphones, smartwatches, personal computers, tablets, and other electronic devices during the day and at night. Whilst these devices are kept close to the eyes, they emit artificial light at night (ALAN) and generate noise. ALAN and noise are also emitted from other indoor and outdoor sources, such as home appliances, road traffic, street lighting, and advertising boards. However, the effect of these exposures has been studied mainly in the adult population, and little is known about their combined effect on adolescents. The present study aims to bridge this knowledge gap by examining the combined effect of ALAN and noise on the quality of sleep of junior high and high school students. Study participants included 81 adolescents (age 13-18 years) living in Tamra, a town in northern Israel. A 41-day experiment was carried out during which participants wore smartwatches, connected to Android smartphones, to monitor their exposures to ALAN and noise and their sleep patterns. The collected data were then analysed using statistical tools and showed that an increase in ALAN in a plausible range of 40-150 lx before sleep is estimated to reduce sleep efficiency (SE), all other factors being constant, by ~18% (t < -16, p < 0.01), whilst an increase in noise from 30 to 60 dB was estimated to reduce SE by ~22% (t < -14, p < 0.01). These estimates are higher than those found for the adult population in previous studies, according to which the effects of these environmental risk factors on sleep duration and quality were estimated to be ~8%-9%.