AbstractSleeping habits of brown capuchin monkeys (Cebus apella) were studied during 19 months in French Guiana. High forest, covering 89% of the 355 ha home range of the studied group, was the only vegetal formation used for sleeping. The sleeping‐focused area of 94 ha, located in the center of the home range, was more frequently used for daily activities. Twenty‐six percent of the individuals spent the night in patawa palms, which account for only 0.62% of the plants of diameter at breast height ≥ 16.1 in the 43 1 ha quadrats used for sleeping. Three major factors seem to affect the preference of patawas as sleeping trees: security, comfort, and social contact. © 1995 Wiley‐L