Background: Sleep constitutes approximately one-third of human life and is vital for health maintenance. Although previous studies have established an association between physical activity (PA) and sleep quality, research on the effect of PA in improving objective sleep indices remains scarce. This study investigates the impact of PA levels on sleep quality and provides direct experimental evidence to support sleep quality interventions among college students.Methods: PA and sleep parameters were assessed using sleep diaries, actigraphy, and polysomnography (PSG). The spectral analysis was performed on PSG-acquired electroencephalographic (EEG) data to examine power distribution variations across distinct sleep stages. Concurrently, venous blood samples were collected for quantitative analysis of serum brain-derived neurotrophic factor (BDNF) levels using enzyme-linked immunosorbent assay (ELISA). Cognitive functions were assessed using the Psychomotor vigilance task (PVT).Results: Actigraphy-derived 7-day average daily steps demonstrated significant positive correlations with PSG-measured sleep efficiency (SE) and non-rapid eye movement sleep stage 2 (N2), while exhibiting negative correlations with wake after sleep onset (WASO) and wake stage. The results of multiple linear regression analysis showed that with the increase in the average daily steps, SE and N2 time increased, and wake stage and WASO decreased. Spectral analysis of sleep EEG data demonstrated that average daily steps positively correlated with the mean power of slow sigma and fast sigma during NREM sleep, as well as mean theta power during REM sleep. Additionally, this study revealed that higher average daily steps correlated with elevated BDNF concentrations and reduced reaction time in the PVT task.Conclusions: This study demonstrates that there is an association between PA and the modulation of sleep architecture and cognitive function among college students. These findings gain additional support from sleep EEG microstructural analyses, with the observed improvements potentially mediated through PA-mediated modulations in circulating BDNF levels.