Research consistently shows that adults who use screens before bed tend to experience worse sleep quality and less sleep overall. A cross-sectional study published by the American Cancer Society (PMC) found that adults with daily pre-bed screen use had a 33% higher prevalence of poor sleep quality and over 7 fewer minutes of sleep per night. Meta-analyses, such as those published in peer-reviewed journals, confirm a statistically significant association between electronic media use and decreased sleep quality in adults (pooled effect size 0.28, P<.001).
The biological mechanism is well-understood: blue light from screens suppresses melatonin, the hormone that helps regulate sleep timing. This leads to delayed sleep onset and increased sleep latency, as demonstrated in systematic reviews. While most evidence is observational and cannot prove strict causation, the consistent findings across diverse populations strengthen the link.
It's important to note that these effects are strongest in adults; studies in youth populations often find weaker or no associations. Additionally, specific factors such as the type of device, content viewed, and whether screens are used in bed can influence the degree of sleep disruption. Nonetheless, major health organizations like the CDC acknowledge the risks of pre-bed screen time for adult sleep.