Recent studies have documented, for the first time, REM sleep in the brains of zebrafish, which is a key animal for genetic studies. Or at least, we didn’t think so until now. However, they sleep more or less in the same way that other animals do, except they never enter deep sleep (there’s no REM phase). The majority of fish look for a place to hide, stop swimming, and reduce their metabolic activity. Some fish sleep during the day, others at night, and others at twilight. As with other animals, there are many different sleep habits. And fish? Do they sleep too?įish don’t need to come to the surface to breathe like aquatic mammals do, but they are much more vulnerable to predators when they’re asleep. Certainly, even sleep is a privilege in the animal kingdom. However, the queen sleeps for a much longer period of time. This is the sleep pattern of the worker and soldier ants. For example, as tireless as they may seem, ants sleep for more or less four hours a day, but this is divided into 250 naps of around a minute at a time. Insects also sleep, but there many differences between the different insect groups. Added to this, they also sleep with only one eye open, on the opposite side to the side of the brain that is asleep. Whilst one hemisphere of the brain sleeps, the other stays conscious enough so that they return to the surface for oxygen. The two hemispheres of the brain alternate, which allows the brain to rest completely whilst they can still breathe, swim (or fly) at the same time. Dolphins, for example, sleep with one hemisphere of the brain still awake. This is a way of sleeping that birds and aquatic mammals have developed to survive. The answer lies in unihemispheric slow-wave sleep (USWS). Instead of sleeping for many hours at a time, they can alternate between eating and sleeping in short periods.īirds and dolphins can sleep with the brain half-awakeĪ question that always intrigued scientists was whether or not animals that spend most of their time in the air or the water were able to sleep. Like other ruminant animals, giraffes spend most of the day eating.

This behavior is also seen in other animals like elephants, horses, and sheep, who are also prey for other animals.Īnother theory that aims to explain this peculiar sleep pattern is their eating habit. If a predator appears, those few seconds to stand up again could make the difference between life and death. Why do they sleep for such short periods of time? Giraffes are much more vulnerable if they sleep lying down. When they go into a deep sleep, they rest their heads on their back, but this will only happen for a fraction of their total rest each day. Giraffes sleep in short intervals of around ten minutes, and the majority of this time tends to be light sleep where they remain standing. However, even so, they don’t sleep for long periods and the longest period of rest doesn’t tend to exceed two hours. These large herbivores only need to sleep between two and four hours a day to get enough rest.

Let’s look at some examples: Giraffes only sleep a couple of hours a day This is the result of their environment and their way of life. In nature, there are certainly a number of animals that sleep very few hours or even just a few minutes and are still able to survive perfectly fine. It also “works” at night, consolidating individual memories and anything that has been learned during the day. When we sleep, the brain doesn’t just get a rest from the various stimuli in our surroundings.

Even bees have shown abnormal and erratic behavior if they are deprived of sleep. Sleeping is a vital process for all animals, and a lack of sleep can have consequences for various bodily functions. Whilst some animals, like koalas, sleep more than 20 hours a day, others only need to sleep for a few minutes. However, as surprising as it might seem, there are no animals that don’t sleep, but how and how much they sleep can vary hugely. But, despite all this, it might appear to you that some animals don’t sleep at all… Furthermore, when sleeping, a number of important neurological functions take place which are important for brain activity, memory, and learning. Falling asleep initiates a whole series of processes that help the body to recover and ensure that bodily functions work properly.

Animals that dont sleep much