When you see hummingbirds flying during the day, you might not realize that they also get a good night’s sleep. In fact, they’re known to sleep at night and enter a state of torpor during which time they look so still that some people assume they are dead. In the morning, they wake up and go about their business, foraging for food again. There are even a few rare occasions when you’ll see hummingbirds fly at night during migration.
As diurnal creatures, hummingbird bedtime begins at dusk. As daylight fades, hummingbirds search for safe and sheltered locations to spend the night. The sites they select must provide protection from nocturnal predators and inclement weather.
While hummingbirds prefer to sleep alone, they’ve been known to roost in groups on occasion. The benefits of group roosting include increased protection from predators and thermoregulation.
During torpor, a hummingbird’s metabolic activity slows down and its heart rate drops dramatically. The birds can’t eat during torpor, so they must rely on stored energy in order to survive the night. Hummingbirds also go through cycles of REM and non-REM sleep, similar to mammals. The exact length of the cycle depends on the season and location. For example, hummingbirds that live in warm climates typically experience longer periods of REM sleep than those in colder regions. These sleep cycles help to regulate their body temperature and prepare them for daytime flight.