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Sleep and Human Performance

Author(s): David F. Dinges, PhD

Complex Animals Sleep and Need Sleep to Survive

Slide Notes
Some people have thought sleep is an acquired habit that is not biologically determined. Thomas Edison—the inventor of artificial light—believed this and was eager to eliminate sleep with inexpensive indoor lighting. Scientific work over the past 100 years has shown that sleep is not only biologically determined, but is biologically essential. Thus far, no complex animal life forms (from fruit flies to humans) have been found that can survive without sleep. Sleep deprivation causes many changes to the brain and body, and death results when sleep deprivation goes on too long. Even mammals that live in aquatic environments (the cetaceans) sleep. Research has shown that some of these marine mammals—such as dolphins and orca—can swim while one of their two cerebral hemispheres sleeps. Humans and other terrestrial mammals do not have this adaptation. When they fall asleep, both cerebral hemispheres do so, which is fine if you’re already in bed, problematic if you’re in class, and very dangerous if you’re driving.

Transcript of Videotaped Presentation (
All complex animals need sleep. And that includes the common fruit fly, otherwise known as Drosophila meanogaster; birds, these are theropods, the current modern day descendants of the dinosaurs; all mammals, including placental mammals, like this leopard or like this nocturnal South American tarsier and of course chimps and humans, but also marsupials, kangaroos, and the ancient order of mammals, the monotremes, like this platypus. Even mammals that live in aquatic environments, like the whale, sea lion, porpoise, and the manatee, or sea cow, need sleep and engage in sleep. The remarkable thing about some of these cetaceans, like the porpoise and the orca, is that they sleep one half of their brain at a time. So one hemisphere of the brain, the right hemisphere, for example, might sleep while the left hemisphere keeps swimming and breathing. And then it switches. Unfortunately that’s not an adaptation that land mammals have, or that humans have, although I’ve heard people say they’d like to have it. We have no idea what consciousness is like for the animals that do it, but it is remarkable that sleep persists even in animals that cannot afford to have both hemispheres asleep at the same time. And of course humans sleep. And they sleep a lot when they’re born, they sleep somewhat less as they age and go through their lifespan. Young children, adolescents and young people need more sleep than they typically get in modern industrialized societies, in part because school start times are very early and children often are up very late with television, games and studying. We now face a sort of epidemic of sleep deprivation among children, adolescents and young adults.

Funded by the following grant(s)

National Space Biomedical Research Institute

National Space Biomedical Research Institute

This work was supported by National Space Biomedical Research Institute through NASA cooperative agreement NCC 9-58.