Penguins live in cold environments, so their sleep needs to be insulated. As such, they don’t sleep for long periods of time in one stretch — instead, they take small naps that add up to quite a bit of rest each day. This serves two purposes: 1) to avoid being too cold while they’re asleep and 2) to help them avert predator attacks by staying alert during their naps.
While some penguins will lie down while they slumber, most species prefer to sleep standing up. This allows them to stay warmer by creating a space between their body and the cold Antarctica ice they sleep on. It also helps them stay awake by increasing their blood circulation. In fact, if you’ve ever seen a penguin colony huddled together on a piece of ice, chances are that they’re all napping in this standing position.
As for the duration of their naps, different penguin species will doze off at various times of the day depending on what they’re doing and where they are. For example, studies of Little Penguins and Galapagos Penguins found that they slept for about 8 hours and 12 hours per day respectively. On the other hand, a study of King Penguins found that they sleep more profoundly in the afternoon after their lunch1.
Another interesting thing to note about penguins’ sleeping habits is that they like to tuck their bill or beak behind one of their flippers while they’re dozing off. While many experts believe that this serve no purpose, other believe that it may help them avert predator attacks by keeping their head and face covered.