Facts on how whales and dolphins sleep
All animals need to sleep. Some of them are like humans and sleep during the night, others are nocturnal and sleep during the day. Pandas sleep more than 40% of the day.
Whales and dolphins have special ways of sleeping. They need to always think about breathing since they are not conscious breathers like us humans. Dolphins sleep by resting one half of the brain at a time to remember breathing and keep one eye open to look out for predators. After about one hour the dolphin will swap to rest the other half of the brain.
Whales don’t sleep like dolphins. They will take a deep breath and sit a few meters underwater, sleeping for up to one hour. They will then come up to take a few breaths and go down again. Whales that took sleeping to the extreme are the Sperm whales. They have been seen sleeping vertical in the water with the head bobbing just under the surface. This made scientists believe that sperm whales can use this when diving (up to 2500m). When they take dives, they could grab a quick nap on the way up to the surface by floating head first.