Why Do Humans And Other Animals Sleep?

To feel rested and refreshed upon awaking, most adults crave 7–eight hours of sleep, although this number varies among individuals (Figure 28.1A). As a consequence, a substantial fraction of our lives is spent in this mysterious state. For infants, the requirement is much higher (almost xvi hours a twenty-four hours), and teenagers need on boilerplate about nine hours of slumber. Every bit people age, they tend to sleep more than lightly and for shorter times, although often needing nearly the same amount of sleep as in early adulthood (Figure 28.1B). Getting likewise trivial sleep creates a "sleep debt" that must be repaid in the following days. In the meantime, judgment, reaction fourth dimension, and other functions are dumb. Drivers who autumn comatose at the wheel are estimated to crusade some 56,000 traffic accidents annually and 1,500 highway deaths.

Figure 28.1

The duration of slumber. (A) The duration of slumber each night in adults is commonly distributed with a mean of 7.5 hours with a standard departure of about 1.25 hours. Thus, about ii-thirds of the population sleeps between 6.25 and viii.75 hours each night. (more...)

Sleep (or at to the lowest degree a physiological period of quiescence) is a highly conserved behavior that occurs in animals ranging from fruit flies to humans (Box A). This prevalence non withstanding, why we sleep is non well understood. Since animals are particularly vulnerable while sleeping, there must be advantages that outweigh this considerable disadvantage. Shakespeare characterized sleep as "nature's soft nurse," noting the restorative nature of sleep. From a perspective of energy conservation, one function of slumber is to replenish encephalon glycogen levels, which autumn during the waking hours. In keeping with this thought, humans and many other animals slumber at night. Since it is generally colder at night, more energy would have to be expended to keep warm were we nocturnally agile. Furthermore, body temperature has a 24-60 minutes cycle, reaching a minimum at dark and thus reducing heat loss. Every bit might be expected, human metabolism measured past oxygen consumption decreases during sleep.

Box A

Styles of Sleep in Different Species.

Any the reasons for sleeping, in mammals sleep is evidently necessary for survival. For example, rats completely deprived of slumber die in a few weeks (Figure 28.2). Slumber-deprived rats lose weight despite increasing food intake, and progressively fail to regulate body temperature. They also develop infections, suggesting an damage of the allowed system.

Figure 28.2

The consequences of full sleep impecuniousness in rats. (A) In this apparatus, an experimental rat is kept awake because the onset of slumber (detected electroencephalographically) triggers movement of the muzzle floor. The control rat can thus sleep intermittently, (more than...)

In humans, lack of sleep leads to impaired retentiveness and reduced cognitive abilities, and, if the impecuniousness persists, mood swings and fifty-fifty hallucinations. The longest documented period of voluntary sleeplessness is 264 hours (approximately eleven days), a record achieved without whatever pharmacological stimulation. The boyfriend involved recovered after a few days, during which he slept only somewhat more than normal, and seemed none the worse for wear.

Source: https://www.ncbi.nlm.nih.gov/books/NBK11108/#:~:text=From%20a%20perspective%20of%20energy,other%20animals%20sleep%20at%20night.

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