o Sleep need is highest when you’re younger and decreases and levels out once you are in your 20s and 30s. People mid 20s and up the optimal amount of sleep predicting the greatest likelihood that you’ll be alive in 5 years is 7 hours. People who sleep more than 7 hours are at substantially greater risk of death in 5 years. The greatest effect of sleep on longevity actually occurs for longer sleep times. Knitting Up “the Ravelled Sleave” Several theories attempt to explain sleep. The restoration theory (Sleep is essential for revitalizing and restoring the physiological processes that keep the body and mind healthy and properly functioning.) was expressed most eloquently by Shakespeare: “Sleep that knits up the ravell’d sleave of care,The death of each day’s life, sore labour’s bath,Balm of hurt minds, great nature’s second course, Chief nourisher in life’s feast . . .” Macbeth : Act 2, Scene 2
In your own words, what role is sleep playing in this quote from Macbeth? Does it match your own experiences? Restoration Theory: As you deduced from Shakespeare’s Macbeth, the restoration theory of sleep claims that the purpose of sleep is to allow the body and mind to recover from the stresses they endure during waking hours. The evidence for this theory is not as compelling as one would hope; athletic performance does not suffer greatly from sleep deprivation despite the common belief that proper sleep before a competition or an exam is crucial to top performance. There is some evidence for a relationship between sleep and physical exertion. One study demonstrated that in the nights following running a marathon, participants’ overall sleep duration increased, as did the total amount of time they spent in deep sleep (a stage we will discuss more shortly). Even if sleep is not crucial for keeping our bodies functioning, it may be important for keeping our minds sharp. Indeed, our ability to perform mentally demanding tasks tends to suffer when we are deprived of sleep. In addition, our executive function declines markedly – we are poorer at maintaining vigilance, have poorer working memory function, and are slower at processing information. The Preservation and Protection Theory: An alternative hypothesis for why sleep occurs is the preservation and protection theory , (A theory that holds that sleep serves an adaptive function. It protects the animal during that portion of the 24-hour day in which being awake, and hence roaming around, would place the individual at greatest risk.) which highlights the more indirect benefits that sleep might provide. This theory posits that sleep occurs to protect the human or animal during that period within 24 hours in which the human or animal would be most at risk.
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- Winter '08