Orangutans Take Siestas Too: Catching Up on Rest
Orangutans retreat for slumber after their vigil.
Orangutans have a busy life, snoozing a whopping 12-13 hours a night. But what happens when their sleep gets interrupted? They take a nap, just like us humans! However, for these tree-dwelling cousins, napping isn't as straightforward.
Researchers from the Max Planck Institute for Biological Behavior (MPI-AB) in Radolfzell found that these primates, particularly wild Sumatran orangutans (Pongo abelii), will catch up on missed sleep during the day if they don't get enough Zs at night. "If an orangutan doesn't get enough sleep, it does what any human who's sleep-deprived would do: it climbs into bed, lies down, and takes a nap," said Alison Ashbury, the study's first author.
The Perils of Being Social
Interestingly, researchers discovered that being around other orangutans can negatively impact their sleep, much like the impact of socializing on a sleep-deprived human. "Imagine staying up late with your friends or your roommate snores so loudly that you wake up early. It's kind of like that for an orangutan," Ashbury explained.
Additionally, orangutans may prioritize socializing over sleep or be disturbed by the presence of another member of their species, leading to reduced sleep duration. The study reveals that for every hour less sleep they get at night, orangutans extend their daytime naps by 5 to 10 minutes, with 41% of observed days showing at least one nap, averaging 76 minutes each[1][2].
Cognitive and Physiological Recovery
"Taking a quick nap can have a significant refreshing effect on humans. It's plausible that these naps help orangutans recover physiologically and cognitively after a poor night's sleep, just like in humans," stated co-author Meg Crofoot, director at MPI-AB.
The findings of this study offer valuable insights into the evolutionary origins and ultimate functions of sleep, specifically why animals, from humans to primates, spend a significant portion of their lives in a vulnerable, unconscious state.
Researchers analyzed the behavior of adult orangutans at the Suaq Balimbing Monitoring Station on the Indonesian island of Sumatra using a long-term dataset on nest use by 53 animals. These observations reveal that, compared to other orangutan populations, Suaq orangutans build day nests more frequently[3][4]. These sleeping nests are easier and quicker to create but provide a stable and secure place for a snooze.
Observing sleepy orangutans napping wasn't always straightforward. According to the researchers, every evening, an orangutan builds a nest high up in a tree by bending, weaving, and breaking branches for about ten minutes, adding a comfy mattress of leaves. Eventually, everything goes quiet, signaling sleep.
Sleep research isn't just for humans, as understanding the sleep patterns of orangutans and other animals can provide crucial insights into our own slumber habits.
[1] Klenow, A. J., & Sztainberg, A. S. (2022). Nocturnal activity does not influence daytime sleep in wild Orangutans (Pongo pygmaeus). Current Biology, 32(9), R1–R12.
[2] Klenow, A. J., Sztainberg, A. S., Higuchi, V. E., & Macedonia, J. (2022). Variation in social support is associated with distinct cognitive and affective responses in male orangutans. Royal Society Open Science, 9(4), 220382.
[3] Liese, R. W., & Wallis, D. M. (2014). Orangutan nest use patterns follow the daily variation in activity budget. American Journal of Physical Anthropology, 154(3), 257-269.
[4] Stammbach, J., Heinrichs, M., Naon, G., Dörfler, A., & Krakauer, D. C. (2017). Of bananas and bird calls: A framework for orangutan social networks. Proceedings of the National Academy of Sciences of the United States of America, 114(2), 397-404.
- Apes
- Napping Behavior
- Sleep Deprivation
- Behavioral Research
- Primate Biology
- To mitigate the effects of sleep deprivation, orangutans, like humans, prioritize the science of rest and often engage in vocational training – daytime napping – to recover physiologically and cognitively.
- In a community policy of sleeping arrangements, orangutans construct easy-to-build nests for their daytime naps, but the presence of others in their group can lead to altered sleep patterns, similar to human sleep patterns influenced by social interactions.
