Sleep - Functions

Functions

Further information: Neuroscience of sleep#Sleep function

The multiple theories proposed to explain the function of sleep reflect the as-yet incomplete understanding of the subject. (When asked, after 50 years of research, what he knew about the reason people sleep, William Dement, founder of Stanford University's Sleep Research Center, answered, "As far as I know, the only reason we need to sleep that is really, really solid is because we get sleepy.") It is likely that sleep evolved to fulfill some primeval function and took on multiple functions over time (analogous to the larynx, which controls the passage of food and air, but descended over time to develop speech capabilities).

If sleep were not essential, one would expect to find:

  • Animal species that do not sleep at all
  • Animals that do not need recovery sleep when they stay awake longer than usual
  • Animals that suffer no serious consequences as a result of lack of sleep

Outside of a few basal animals that have no brain or a very simple one, no animals have been found to date that satisfy any of these criteria. While some varieties of shark, such as great whites and hammerheads, must remain in motion at all times to move oxygenated water over their gills, it is possible they still sleep one cerebral hemisphere at a time as marine mammals do. However it remains to be shown definitively whether any fish is capable of unihemispheric sleep.

Some of the many proposed functions of sleep are as follows:

Read more about this topic:  Sleep

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