Overview

• The study relied on nest-use data collected over 276 nights and 455 days between 2007 and 2021 at the Suaq Balimbing Monitoring Station in Sumatra.
• Wild Sumatran orangutans typically sleep almost 13 hours per night but extend their total rest with midday naps when their nocturnal sleep is shorter.
• Researchers observed naps on 41 percent of days, with an average duration of 76 minutes and an increase of 5 to 10 minutes for each hour of lost night sleep.
• Daytime nests are simple structures built in under two minutes, while nighttime nests take about ten minutes to assemble and include a leafy mattress.
• Proximity to other orangutans was linked to shorter nocturnal sleep, highlighting how social factors disrupt rest and underscore the recuperative role of naps.