These amphibians can go for long periods without sleep. During hibernation or in extreme conditions, they can remain motionless and dormant for extended periods without traditional sleep cycles.
Dolphins are known for their ability to rest one hemisphere of their brain while keeping the other awake. This unihemispheric slow-wave sleep allows them to maintain awareness and control essential functions like surfacing for air while resting.
These tall creatures have very short and irregular sleep patterns, often sleeping for short bursts that total about 4.6 hours a day. They often nap while standing and remain vigilant for predators.
Elephants have relatively short periods of sleep, averaging around 3-4 hours a day. They have a fragmented sleep pattern, often sleeping while standing.
These seabirds can sleep while flying, utilizing unihemispheric sleep, similar to dolphins. They can remain in flight for extended periods without traditional sleep.
Many bat species exhibit unique sleep patterns due to their nocturnal lifestyle. They engage in short periods of sleep, typically a few hours during the day, roosting upside down.
Studies suggest that some sharks, including bull sharks, do not sleep in the same way mammals do. They may exhibit periods of restful inactivity but don't enter a state of unconsciousness as mammals do.
These creatures lack a central nervous system but exhibit behaviors akin to sleep or restful periods. While they don't sleep in the same way vertebrates do, they enter periods of reduced activity.