A new study from the University of Haifa provides the first real-world evidence quantifying how artificial light at night (ALAN) and noise together degrade sleep quality in adolescents. The findings show effects roughly twice as large as those previously reported in adults.
What they found
Researchers recruited 81 adolescents aged 13 to 18 living in Tamra, a town in northern Israel, and tracked them over 41 consecutive days. Each participant wore a smartwatch synced to an Android smartphone that continuously recorded environmental light levels, ambient noise, and sleep patterns, including sleep efficiency and the ratio of deep sleep to light sleep.
The analysis revealed that ALAN exposure in the range of 40 to 150 lux before sleep reduced sleep efficiency by approximately 18% (t < -16, p < 0.01). Noise levels rising from 30 to 60 decibels cut sleep efficiency by roughly 22% (t < -14, p < 0.01). Both effects were statistically robust and independent of one another, meaning the presence of one risk factor did not diminish the impact of the other.
The researchers also examined the deep sleep to light sleep ratio and found that both ALAN and noise shifted sleep architecture toward lighter, less restorative stages. Notably, the timing of exposure mattered. ALAN before sleep had a stronger impact on sleep efficiency than ALAN during sleep, consistent with findings from earlier adult studies. This makes biological sense: ALAN suppresses melatonin production, while noise exposure elevates cortisol, and both hormonal disruptions are amplified when they occur during the pre-sleep window when the body is preparing for rest.
These effect sizes are roughly double those found in comparable adult research, where the combined impact of ALAN and noise on sleep duration and quality was estimated at 8 to 9%. The authors suggest that adolescents may be particularly vulnerable because of their high device usage patterns and the physiological sensitivity of the developing brain to environmental disruption of sleep regulation. The study used consumer wearable technology, whose reliability for sleep monitoring has been validated in prior work by the same group.
Why it matters
Adolescents are among the heaviest users of smartphones, tablets, smartwatches, and personal computers, often keeping these devices close at hand throughout the night. Beyond the screens themselves, ALAN and noise also come from street lighting, advertising boards, home appliances, and road traffic sources that are largely outside a teenager’s control. This combination of device-generated and environmental exposure is a near-universal feature of modern adolescent life.
Sleep deprivation in this age group is linked to anxiety, somatic complaints, endocrine disruption, increased sympathetic nervous activity, elevated stress hormones (cortisol and adrenaline), and reduced leptin levels. Metabolically, chronic poor sleep increases insulin resistance and raises blood glucose. The fact that ALAN and noise effects are amplified in adolescents compared with adults means that standard environmental guidelines, which are often based on adult data, may not adequately protect younger populations. The findings suggest that public health recommendations should account for age-specific sensitivity when setting thresholds for bedroom light and noise.
The study also demonstrates the feasibility of using consumer wearable devices for real-world sleep environmental monitoring. Smartwatches and smartphones, already ubiquitous among teenagers, can serve as practical research tools for capturing exposure patterns that would be difficult to measure in laboratory settings or through self-report alone.
Limits
The study is observational, not experimental, so causal inference is limited. The 81 participants were all from a single town in northern Israel, which may affect generalizability to other regions with different light and noise profiles. Although the analysis controlled for multiple confounding factors, unmeasured variables such as caffeine intake, evening exercise, or emotional stress could contribute to some of the observed sleep changes. The study also relied on smartwatch-based sleep staging, which is less precise than polysomnography for distinguishing deep sleep from light sleep.
Bottom line
Adolescents who face elevated light and noise levels before sleep lose 18 to 22% of their sleep efficiency, an effect roughly twice that seen in adults. Reducing bedroom light and noise during the pre-sleep window could meaningfully improve sleep quality in this vulnerable age group.
Source
Shama H, Tzischinsky O, Portnov BA. “Investigating the Combined Effect of Artificial Light at Night and Noise on Sleep Quality of High School Students.” Journal of Sleep Research, 2026;35(4):e70301. doi: 10.1111/jsr.70301