Bullfrogs: Research suggests that bullfrogs may not require sleep in the same way other animals do. Instead, they remain alert for extended periods. While they can rest, it's believed that they maintain a state of alertness rather than entering a traditional sleep.
Dolphins and Other Aquatic Mammals: Dolphins, whales, and some seals have an unusual way of resting: they shut down only half of their brain at a time. The other half remains alert to help them maintain breathing patterns, regulate temperature, and watch for predators. This is often referred to as unihemispheric slow-wave sleep.
Alpine Swifts: These birds are capable of flying for months without stopping, even apparently sleeping while airborne. Studies suggest they can use unihemispheric slow-wave sleep, allowing one half of the brain to rest while the other half keeps them flying.
Giraffes: Although giraffes do sleep, they do so for very short periods—typically just a few minutes at a time. The total sleep time in a 24-hour period may be only around 30 minutes, which is incredibly brief compared to other mammals.
Great Frigatebirds: Like the alpine swifts, frigatebirds can sleep while flying. They too exhibit unihemispheric sleep and have been recorded sleeping in very short bursts that add up to around 45 minutes per day while on long flights over the ocean.
Walruses: Walruses can perform a bizarre form of sleep where they manage to rest half of their brain and keep the other half alert, similar to dolphins. However, walruses have also been observed sleeping underwater or hanging vertically with only their heads above water.
Elephants: Wild elephants sleep surprisingly little, averaging only about two hours per night and often going without sleep for long periods. They sleep standing up on most nights but will occasionally lie down to achieve REM sleep.
These unique sleep patterns show the incredible adaptability of different species to their environments and survival needs. While some of these animals do sleep—albeit in unusual or minimalistic ways—the idea that they don't sleep at all is more of a simplification or myth based on their extraordinary behaviors compared to human sleep patterns.