Why do mammals need sleep

Increasing evidence shows that the circadian system develops neonatally before an infant is born. Primate infants have responded to light in the early stages of life. It is hypothesized that exposure to low light can help regulate the developing system. Because many sleep and overall health concerns stem from disordered circadian rhythms, this research can assist with future neonatal care for humans. Alexa Fry is a science writer with experience working for the National Cancer Institute.

She also holds a certificate in technical writing. Logan has extensive experience testing sleep products and producing sleep content. She is also a Certified Sleep Science Coach. Learn more about the differences between how humans and fish sleep, and find out how to know when your fish…. Drooling during sleep is normal, but excessive drooling can be caused by your sleep position, GERD, and allergies.

Get tips…. Are you a night owl surrounded by early birds? We explain the science behind late chronotypes and share tips for…. Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies.

It is mandatory to procure user consent prior to running these cookies on your website. The Sleep Foundation editorial team is dedicated to providing content that meets the highest standards for accuracy and objectivity. Our editors and medical experts rigorously evaluate every article and guide to ensure the information is factual, up-to-date, and free of bias. Updated February 17, Written by Alexa Fry. Medically Reviewed by Logan Foley.

Sign up below for your free gift. Your privacy is important to us. Was this article helpful? Yes No. Logan Foley Certified Sleep Coach. Purves, D. Why do humans and many other animals sleep? In Neuroscience. Hirshkowitz, M. Sleep Health, 1 1 , Campbell, S. Animal sleep: A review of sleep duration across phylogeny. Gravett, N. PLoS One, 12 3 , e Aserinsky, E.

Just think, if scientists can discover how sleep works, maybe one day we can use that information to make studying easy! Lindsey O'Connell. Who Needs Sleep Anyway?. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteers page to get the process started.

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Think Fast! Tigers are Grrrrreat! Who Needs Sleep Anyway? These variations include duration and depth of sleep, and even how it works in the brain. Humans, like all other great apes, are monophasic sleepers, meaning we sleep in one long interval during a hour period. Bonobos , chimpanzees , gorillas , and orangutans all also build sleeping platforms in trees, away from predators and insects, a jungle version of a bed. Gorillas sleep for 12 hours but orangutans get around the same eight hours that humans do.

In some other primates, as in most mammals, sleep is polyphasic, with several alternating periods of sleep and activity in a hour cycle. Dogs have wake-sleep cycles of about 83 minutes and get a little more than 10 and a half hours of sleep per hour cycle. The reason great apes have such long, luxurious sleep compared to the fitful, shorter sleeps of their monkey cousins has to do with those sleeping platforms. Monkeys have to balance on hard branches where they are easily awakened by potential danger or other monkeys—which is helpful to them but not good for extended sleep.

When apes started getting bigger, the branches they once slept on could no longer hold their weight—so they started building something that would. Being able to lay down, away from the dangers of predators and other distractions allowed them to sleep longer, more securely, and more deeply. A study showed that orangutans do, indeed, sleep better than their baboon cousins.

Dolphins, meanwhile, can stay alert with half of their brain while the other half can fall into a deep sleep. This enables dolphins to sleep with one eye open, looking for predators. This sleeping pattern—which dolphins share with other cetaceans, manatees, eared seals and some birds—is called unihemispheric slow wave sleep, a deep state of sleep in which rapid eye movement or REM sleep does not occur.

REM sleep is the sleep state in which the brain is most active, breathing becomes more rapid, and most muscles become temporarily paralyzed.

The importance of REM sleep has been a subject of scientific debate concerning how much of a role it plays in memory and learning. Dolphins are highly intelligent but possibly never experience REM sleep, says David Raizen , a neurologist at the University of Pennsylvania, because if they did experience the same muscle paralysis as terrestrial animals they would sink to the bottom of the ocean and drown.

Frigate birds fly for months over the ocean and can engage in both regular sleep and use half their brain at a time to sleep during soaring or gliding flight. They sleep only while on rising air currents which allow them to gain altitude and keep them from falling in the water during the short second bursts of total sleep they grab while flying.

Lions sprawled out on the Serengeti. A hippo dozing on a mudbank. These slumberous scenes may make folks wonder why these other mammals seem to be getting so much more sleep than humans. Do they actually need more sleep? Are they just sleeping because they can? Should humans be sleeping more, too? Related: Can any animal survive without sleep? Though constantly studied, sleep is one of the great mysteries modern science hasn't completely cracked.

Raizen said scientists have identified relationships between sleep and animal function — certain kinds of sleep can increase a critter's ability to fight off illness or consolidate memories.