All animals with a decent-sized brain engage in sleep – a period of rest when the brain enters an altered state of consciousness less immediately sensitive to its surroundings.
Why do animals sleep?
We do all sorts of useful and necessary things better when we are asleep, such as flushing metabolic by-products from the brain, consolidating memories and growing. And if we go without sleep, we are likely to suffer increased fatigue and, eventually, a variety of unwelcome physical and mental consequences. Experiments on rats, for example, show that sleep deprivation compromises the body’s ability to heal wounds, fight cancer and combat infection.
Some animals take sleep to the next level. Dolphins, for instance, snooze with only half of their brain at a time. This is vital to their survival, allowing them to both come to the surface to breathe and remain vigilant for sharks while in the land of nod.
Find out how hibernation and torpor differs to sleep
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