The Sociality of Sleep in Animal Groups

演化之聲
2 days ago
4 min read

Sleep is a biological phenomenon found in nearly all animals. However, sleep duration, architecture, and physiological characteristics can vary greatly among species and even among individuals within the same species. Why animals have evolved such diverse sleep patterns remains unclear.

The interplay between sleep and sociality in wild animal groups. Shown is a sleeping troop of olive baboons（Image source：Chakravarty, P et al. (2024). Illustration by Javier Lázaro.， CC BY 4.0 。）

Advances in technology have made it increasingly possible for researchers to record animal sleep directly in the wild. These studies have revealed that sleep patterns are shaped by ecological conditions. For example, animals living in the wild may sleep for different durations than captive individuals, and some species may even shift between diurnal and nocturnal activity patterns.

Most previous studies have treated sleep as an individual behavior, paying relatively little attention to the fact that many animals actually sleep in groups. The researchers argue that understanding the evolution of sleep in nature requires considering not only environmental factors but also the social interactions that occur among animals.

Growing evidence indicates that social factors play an important role in shaping sleep patterns. For example, western honey bees (Apis mellifera) synchronize their circadian rhythms through vibrations transmitted within the hive. Different groups of meerkats (Suricata suricatta) exhibit distinct sleep "traditions," and these traditions can persist across generations despite complete turnover of group membership. Olive baboons (Papio anubis) sleep less when surrounded by larger numbers of nearby group members, while bumble bees (Bombus terrestris) reduce their sleep in order to care for offspring.