Dolphins have a unique way of sleeping where only one half of their brain sleeps at a time, while other half stays awake. This allows them to swim, breathe consciously, and remain alert of their surroundings while resting. They take short naps throughout the day and night, keeping one eye open.
Octopuses have one of the most fascinating sleep behaviours in the animal kingdom. Octopuses have two sleep stages, quiet and active sleep. In quiet sleep they stay still and pale, while in active sleep, their skin changes colour, eyes move, and arms twitch.
Sea Otters often sleep floating on their backs in the water. They sleep in groups called rafts and to avoid drifting apart while sleeping, they hold hands of other otters. This also helps these species to stay warm in the water.
Alpine Swifts exhibit remarkable sleeping patterns where they sleep while flying. These birds can fly continuously for 120 days and take micro naps mid flight. They rest with one half of their brain while the other half remains alert.
Elephants sleep for only about 2 to 4 hours a day, often while standing. They can go several days without sleep, especially during migration. Their sleep is usually broken into short intervals and they rarely lie down unless they feel completely safe.
At night, Parrotfish secret a mucous cocoon around themselves which acts like a protective sleeping bag. This slimy bag masks their scent and keeps them safe from the predators.
Giraffes have one of the most minimalistic sleep routines. They sleep for just 4 to 5 hours a day and take naps that often last only a few minutes. They have the ability to sleep while standing which helps them stay alert.
Walruses are massive marine creatures that can live without sleeping for about 84 hours. These mammals have the ability of sleeping in water as well as on the land in various different positions.
Sloths can sleep for 15-20 hours daily, while hanging upside down from the tree branches. This allows the metabolism to slow down in their body which further results in conserved energy, that too on a low-nutrient diet.