The timing of digital device use emerges as more critical than total usage when examining sleep quality in young adults. This distinction challenges the common assumption that all screen time equally affects rest, pointing instead to evening and bedtime exposure as the primary culprit in sleep disruption. The analysis of multiple research domains reveals consistent patterns across diverse populations showing deteriorated sleep quality, delayed onset, shortened duration, and next-day impairment linked specifically to nighttime device engagement. Problematic usage patterns and addiction-like behaviors compound these effects beyond what duration alone predicts. The research identifies several mechanisms driving this relationship, including bedtime procrastination behaviors, rumination triggered by social media content, and fear of missing out that keeps users engaged past optimal sleep times. Individual chronotype differences also influence susceptibility, with evening-preference individuals showing greater vulnerability to digital sleep disruption. Cross-cultural studies demonstrate these patterns persist across different societies, suggesting biological rather than purely cultural mechanisms. While much research relies on self-reported measures, emerging objective sleep and exposure data support these associations. The evidence base spans observational studies through controlled interventions, with experimental designs confirming causal relationships between evening screen exposure and sleep degradation. This convergent evidence suggests that sleep hygiene recommendations should emphasize timing restrictions over total usage limits. The findings have particular relevance for young adults navigating increasing digital integration while establishing long-term sleep patterns that influence decades of health outcomes.