Group sleeping can impact when animals sleep, how long they sleep for, and how deeply they sleep. For example, groups of meerkats time their sleep according to “sleep traditions”; olive baboons sleep less when their group size increases; bumblebees suppress sleep in the presence of offspring; and co-sleeping mice can experience synchronized REM sleep. To fully understand both sleep and animal social structures, we need to pay more attention to the “social side” of sleep, animal behaviourists…