Orangutans catch up on lost sleep by daytime naps – just like us!

By Andrea L. Permana

Wild orangutans have a remarkable way of dealing with disrupted sleep: they take naps during the day to make up for it.

In our new study published in Current Biology, we found that Sumatran orangutans maintain balanced sleep patterns, known as sleep homeostasis (a mechanism that regulates how much sleep they need) by napping during the day if their sleep overnight is reduced. 

Using the time orangutans were observed to lay down and stop moving in their nests as an indication of sleep, we monitored sleep-wake patterns of our study population at Suaq Balimbing, a coastal peat swamp forest in Sumatra. Despite volatile weather conditions, fluctuating food availability, and social disruptions, these intelligent apes showed a surprising ability to adapt. On average, this population of orangutans sleep for almost 13 hours a night. We found that having a companion nearby, a long journey the previous day, and warmer temperatures overnight led to a shorter night sleep, but like us, orangutans didn’t just power through, they took longer naps the next day to compensate! This is the first time this behaviour has been documented in wild great apes and may remind many of us of our own behaviour.

image of orangutan napping in a nest

Why does this matter?

Lack of sleep is not just tiresome, it can have serious consequences, including weakened immune systems, reduced attention and impaired memory. So, for species like orangutans, who rely on their mental skills for finding food, navigating large home ranges, and maintaining social relationships, getting enough sleep is essential. We know that arboreal nests provide orangutans with a secure and comfortable place to sleep but we are still trying to understand how much and how well wild orangutans sleep once they bed-down in their nest. Conservation is not just about keeping forests standing, it is about ensuring those forests can support the full range of natural behaviours that orangutans and other inhabitants need in order to thrive. Our research reinforces the importance of preserving undisturbed habitats where orangutans can feed and move freely, and rest when they need it.

Our work also highlights the incredible adaptability of orangutans. Their ability to manage their sleep in response to changeable daily situations reminds us that these animals are intelligent and sensitive beings. As human activities continue to encroach on their habitats, ensuring orangutans have the space and conditions they need to rest safely is an important consideration to policy makers, rescue centres and zoos around the world.

We’re proud to contribute to this growing body of knowledge and grateful to all those working on the ground to protect these incredible animals.

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