This Animal Sleeps a Whopping 23 Hours Every Day

The post This Animal Sleeps a Whopping 23 Hours Every Day appeared first on A-Z Animals.

Despite decades of research, scientists admit that they still have a lot to learn about sleep. In general, sleep can be defined as a period of reduced activity that is relatively easy to reverse. Hibernation, therefore, is not sleep because it takes a long time to reverse the hibernation state. Studies on humans have revealed that when people are asleep, they experience physiological changes to their brains, changes in body temperature, and changes in cardiovascular and respiratory activity. But what about animals?

From the limited research conducted so far, most experts agree that animals who possess some form of nervous system can indeed fall asleep. So, simple organisms like bacteria, which do not have a nervous system, never take a nap. In contrast, some insects (such as cockroaches) certainly have quiescent behaviors — a state when they are inactive as indicated by a lack of motion and energy. However, it’s unclear if this can strictly be described as sleep. There is evidence of activity/rest cycles in fish, amphibians, and reptiles. Research identifying a sleep state in both land and marine mammals is much more convincing.

This begs the question, how much sleep do animals (including humans) need? Let’s take a look at the sleep requirements of some animals. Some of them barely bother to wake up at all!

African Elephant – 2 Hours Per Day

In the wild, African elephants (the largest land mammals on the planet) average a total daily sleep time of two hours. This mostly happens between 2 a.m and 6 a.m. This is the shortest sleep time of any mammal identified to date. These elephants sleep standing up mainly, but every three or four days, they get down on the ground to sleep. Captive elephants sleep a little longer in general and have been spotted sleeping standing up while resting the end of their trunk on the ground. Another interesting finding is that the elephants can go for 46 hours without sleep. Their sleep seems to be initiated by air temperature and humidity. They also find a new place to sleep each night.

Horse – 3 Hours Per Day

Horses are polyphasic sleepers, which means that they sleep over multiple periods. They have around three hours of sleep made up of several episodes of a few minutes each. When they are standing up they enter a slow wave sleep. If they can lie down, however, they are able to enter an REM (Rapid Eye Movement) sleep. When horses are in REM sleep they lose tone in their muscles and would therefore fall over if they were standing up. Overall, REM sleep accounts for around 30 minutes of their total sleep. Horses can suffer from sleep disorders like hypersomnia (excessive sleeping) and narcolepsy.

Fish – 3 Hours Per Day

There are over 30,000 species of fish, and sleep patterns have been studied in only a few of them. The zebrafish (Danio rerio), however, has been used extensively in sleep research, so we have chosen them as an example. They are a diurnal species, which means that they are more active during the day. Experiments over a 10-hour ‘night’ (created by turning artificial lights on and off) have shown that the adult fish were asleep for 3.3 hours. Other fish species are nocturnal, including some sharks who sleep during the day.

Many other species of fish appear to sleep, but it is not necessarily the same experience as human sleep. At this time they are much less responsive and some completely stop moving and allow themselves to be handled. Because fish rely on the flow of water through their gills to get oxygen, staying still is very risky! So, some of them sleep facing a current of water. Others use a process called unihemispheric sleep where only half of their brain sleeps at a time. The other half keeps them swimming. Being asleep makes you very vulnerable so fish protect themselves in a number of ways. Nurse sharks rest on the ocean floor or near caves whereas rainbow wrasse burrow in the sand. Parrot fish sleep under coral and even make themselves a protective mucus cocoon bed.

Giraffes – 4 Hours Per Day

Studies on captive giraffes have shown that they sleep an average of four hours per day, but this is only part of the story. Wild giraffes live on the African Savanna, and as a prey species (they are hunted by lions), they need to constantly monitor their environment. Therefore, wild giraffes may sleep for as little as 30 minutes a day.

They have several different types of sleep associated with different sleeping positions. The most common sleeping position is standing up, possibly leaning against a tree. In this position, the giraffes are not so vulnerable as they can rouse themselves quickly to flee from a predator. During recumbent sleep, the giraffe lies down with its legs folded. Finally, during paradoxical sleep (the deepest sleep), they lie down and twist their neck so that they can use their rear end as a pillow. This is a very risky position and is only really seen in captive giraffes.

Another reason giraffes sleep so little is that they are ruminating animals and need to constantly chew their food to break it down. You can’t chew when you are asleep.

Sheep – 5 Hours Per Day

As diurnal animals, sheep are active during the day, and they get most of their sleep at night. However, they only sleep for around five hours in total. They are also ruminants and need to be upright to eat and digest their food by chewing their cud. This limits the amount of REM sleep they can have to about 2.5% of the total. If you see a sheep lying down, it is probably in REM sleep. As a prey animal, sheep are very vulnerable in this state and so that likely limits the amount of time they spend in it.

Pigs – 7.5 Hours Per Day

Domestic pigs prefer a sleeping area that is dry and free from draughts. Most domestic pigs will choose to sleep together in a pile, but the more dominant animals sleep alone. The lowest pigs in the hierarchy will sleep at the edges of the big group. When they are comfortable, pigs sleep on their side with their legs stretched out in front of them.  They sleep between seven and eight hours a day, most of which are at night. If it is cold, they will find a warm and dark spot to sleep.

Wild hogs, however, have different sleeping patterns. Studies have shown that they sleep an average of 10.43 hours a day in 24 sleeping sessions, the longest of which was 2.1 hours. Their sleep quality was poorest when it was hot and best when it was cool and raining or snowing. Interestingly, the wild boars studied slept primarily during daylight.

Adult Humans – 8 Hours Per Day

Doctors recommend that adult humans get between seven and nine hours of sleep a day. Babies up to a year old need a lot more – up to 16 hours a day. Teens also need up to 10 hours a day. Humans typically undergo between four to six sleep cycles per night which vary in length but generally last around 90 minutes. Most humans sleep in a recumbent position but some people sleep in a sitting position if they have to. One sleep cycle is made up of three non-REM stages and one REM stage. The deepest sleep is the NS stage where it is hard to wake someone and muscle tone, pulse, and breathing rates decrease. Most human sleep takes place during the night.

Dog – 10 Hours Per Day

Canine sleeping patterns are similar to humans but there are some differences. Adult dogs need between eight and 13.5 hours a day. Their longest sleep is during the night but they add on several naps during the day. Many dogs spend up to 37% of their day sleeping.

When dogs first fall asleep, they enter slow wave sleep during which their heart rate decreases and their blood pressure drops. Within 10 minutes they transition to REM sleep and you may see them moving and twitching as they dream. However, dogs spend very little time in REM sleep – they spend more time in a lighter sleep when they can leap up and become active right away. Dogs like to have a regular sleep schedule and can suffer from sleep disorders such as obstructive sleep apnea (muscles blocking the airway) and narcolepsy.

Chimpanzee – 10 Hours Per Day

Captive adult chimpanzees sleep between 8.8 and 12 hours a day in 90-minute sleep cycles. In all, they enjoy around two hours of REM sleep. To get a good night’s sleep, chimpanzees build nests. These help with temperature regulation and protect them from predators when they sleep.

Even though chimpanzees are diurnal and mainly inactive at night, they have been observed changing their posture. Brief wakeful periods may allow them to check for predators but they can also be disturbed by other group members. Chimpanzees don’t like losing out on sleep. When their sleep has been disrupted it affects their behavior the next day.

Golden Hamsters – 14 Hours Per Day

Golden hamsters are popular pets and need around 14 hours of sleep. They divide this between several sleeps (polyphasic sleep). Hamster sleeping patterns have been studied very closely because they have been used as a laboratory model to study circadian rhythm sleep patterns. We know that hamsters enter an REM sleep during which they twitch their eyes and paws but we do not know if they are actually dreaming. Another extraordinary finding is that captive hamsters are nocturnal but wild hamsters are diurnal. Scientists have not yet figured out why this is but environmental cues in the wild may explain it. Older hamsters have different sleep patterns to younger ones.

Owl Monkeys – 17 Hours Per Day

Owl monkeys are the only nocturnally-active simian primate. When sleeping in the wild, they will search out a hole in a tree trunk or an entanglement of climbers quite high up in trees so that they are hidden while they rest. They sleep for around 17 hours in total. The monkeys experience both REM and non-REM sleep. Researchers have suggested that they are able to sleep for so long because they have the developed of hiding away to have a sleep where they are safe from predators.

Snakes – 23 Hours Per Day

There are around more than 3,000 species of snakes and some of them have a reputation for being very sleepy. The ball python, for example, has been recorded sleeping 23 hours a day!

This excessive sleeping can be explained by both their size and diet. Ball pythons swallow their prey (in the wild this would be large rats) whole. It takes a lot of energy for their body to break down the entire rat’s body and so it makes sense for them to sleep through the process and direct all their energy towards their digestion. Snakes don’t have eyelids so they can’t close their eyes when they are asleep. This makes it hard to tell if they are taking a nap!

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