Sleep length

Dayton Department of Veterans Affairs Medical Center, Wright State University, Kettering Medical Center, and the Wallace Kettering Neuroscience Institute, Dayton, Ohio, U.S.A. 

6 hr of sleep (5) and accumulation of such deficits over consecutive nights (6). Declines in psychomotor performance have been found after as few as 3 nights of 

7 hr of sleep (7). Based on these data, one might conclude that almost one third of normal young adults accumulate sufficient sleep deficits across a normal workweek to precipitate significantly impaired alertness and performance. Such data 

This chapter will review current knowledge about individuals with characteristic long and short sleep patterns, identify some limitations of this research, and suggest some additional studies that might help improve the understanding of differences in sleep requirement versus sleep reduction or sleep deprivation. 

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Strogatz, S. H., Kronauer, R. E. Czeisler, C. A (1986). Circadian regulation dominates homeostatic control of sleep length and prior wake length in humans. Sleep 9, 353-64. 

Webb WB, Agnew HW Jr. The effects of a chronic limitation of sleep length. 

Akerstedt T, Folkard S. The three-process model of alertness and its extension to performance, sleep latency, and sleep length. Chronobiol Int 1997 14 115-23. 

Pilcher JJ, Lambert BJ, Huffcutt AI. Differential effects of permanent and rotating shifts on self-report sleep length a meta-analytic review. Sleep 2000 23 155-163. 

Benoit O, Foret J, Bouard G, Merle B, Landau J, Marc ME. Habitual sleep length and patterns of recovery sleep after 24 hour and 36 hour sleep deprivation. Electroencephalogr Clin Neurophysiol 1980 50 477-485. 

Many studies of long- and short-sleeping humans were published between 1970 and 1987. The studies fall into two groups (a) most of the papers were naturalistic comparisons of people with characteristic sleep lengths of more than 9 hr/day with other individuals sleeping 6 or fewer hr/day (b) a few studies identified a small group of people with extremely short sleep lengths (less than 3 hr/day) in an attempt to document that such individuals did exist and did not develop symptoms of extreme sleepiness. 

White RM. Sleep length and variability measurement and interrelationships Unpublished dissertation, University of Florida, 1975. 

Human sleep occurs involuntarily. That is, with rare possible exceptions, humans cannot volitionally change their brain state from wakefulness to sleep. The environment and behavior can be manipulated to increase the likelihood of sleep, but the neural activity that brings about sleep is essentially involuntary. Similarly, the maintenance of sleep (i.e., sleep length) and the termination of sleep (awakening) are endogenous processes, rather than under voluntary control. In fact, when individuals wish to impact the awakening process, they rely on external stimuli (e.g., alarm clock). In sum, endogenous neural processes control ... 

Like all biological functions, sleep length varies widely. If the number of people who sleep for various durations is plotted on a graph, the result is a bell-shaped curve. Estimations of the chance of falling within 1, 2, or 3 standard deviations from the mean are shown below. Only one in a thousand people falls outside these limits, but such short or long sleepers do exist. 

L-Tryptophan, a precursor of serotonin has also been shown in normal subjects to reduce sleep latency and Increase sleep length without altering the qualitative characteristics of polygraphically recorded sleep . In a double-blind study in hospitalized insomniac patients, doses of 4 to 5 g of L-tryptophan significantly increased sleep time, reduced sleep latency and reduced the number of awakenings. ... 

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