Scrolling Into Sleep: Smartphone Use and Sleep Architecture in Young Adults

Smartphone use has increased exponentially over the past two decades and has become widely integrated into daily life, including before sleep. Growing evidence suggests nighttime smartphone use is associated with delayed sleep onset, reduced sleep duration, and poorer sleep quality in young adults. However, most evidence relies on subjective measures, and objective sleep recordings remain limited. The present study addressed this limitation by objectively assessing nighttime smartphone use and sleep, using polysomnography to characterize sleep architecture and actigraphy to assess sleep-wake patterns. Healthy participants aged 18–25 years (n = 10) were assigned to two groups based on smartphone use before bedtime (use allowed vs. use not allowed, n = 5 each). Preliminary results showed no significant group differences in total sleep time or overall stage durations. However, the smartphone-use group showed a significantly shorter first sleep cycle than controls (88.9 ± 7.2 vs 161.4 ± 44.6 min, p = 0.021) and fewer sleep spindles during this cycle (33.9 ± 27.6 vs 110.7 ± 51, p < 0.05). These preliminary findings suggest that differences in smartphone use before bedtime, even over a single night, may be associated with measurable differences in the earliest sleep cycle, rather than with overall sleep architecture. Additional analyses are needed to confirm the robustness of these associations and their relevance for healthier digital and sleep habits in young adults.