Early life stress (ELS) significantly impacts neurodevelopment and behavior. Recent studies suggest a strong link between ELS and poor sleep quality. Poor sleep correlates with increased risk of psychiatric disorders such as anxiety and vulnerability to stress. In this study, we investigated ELS effects on sleep architecture and spindle activity in mice. Two groups were used: ELS group experienced maternal separation for 3 hours daily from postnatal day 1-14, and a stress-naive control group. At the 8 weeks age, EEG and EMG electrodes were implanted for sleep recording. While wake and NREM sleep durations didn't differ, ELS mice had longer REM bouts duration, possibly reflecting coping mechanisms to early stress, crucial for memory consolidation and emotional regulation. Moreover, ELS mice showed greater transitions from NREM to REM to wake, indicating fragmented sleep. ELS mice exhibited lower delta power during daytime wake phases, suggesting reduced sleep drive, yet higher delta power during nighttime NREM sleep, indicating increased sleep drive during typical awake periods. Additionally, theta bandpower during the daytime wake phase decreased in ELS mice suggesting reduced drive for sleep, while higher theta power during nighttime REM sleep may signify a compensatory mechanism for decreased daytime sleep. ELS mice exhibited longer spindle durations during both daytime and nighttime sleep, suggesting heightened vigilance and increased brain activity during sleep. These findings highlight the intricate relationship between ELS and sleep architecture, with potential implications for synaptic plasticity and cognitive function. Understanding these mechanisms may offer insights into sleep disorder development following ELS exposure.