This exploratory study examined family sleep patterns and quality in a setting of normative napping and cosleeping. Participants were 78 members of 16 families from 2 locales in Egypt (Cairo and a village). Each family member provided a history of sleeping arrangements, I week of continuous activity records, and details of each sleep event. Sleep records documented late-onset and dispersed sleep patterns with extensive cosleeping. Of recorded sleep events, 69% involved cosleeping, 24% included more than 1 cosleeper, and only 21% were solitary. Mid-late afternoon napping occurred on 31% of days, and night sleep onsets averaged after midnight. Age and gender structured sleep arrangements and, together with locale, extensively explained sleep behavior (onset, duration, total) and quality. Cosleepers had fewer night arousals, shorter and less variable night sleep duration, and less total sleep. Increased solitary sleep in adolescents and young adults was associated with increased sleep dysregulation, including exaggerated phase shifts in males and more nighttime arousals in females. Where normative, cosleeping may provide psychosensory stimuli that moderate arousal and stabilize sleep. Such moderating features may address important self-regulatory developmental needs during adolescence.