THE TEACHING ECONOMIST - William A. McEachern 
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Issue 23, Fall 2002
William A. McEachern, Editor
Sleep On It
In the Fall 2001 issue of The Teaching Economist, I wrote about the challenge of trying to teach sleep-deprived students (all back issues can be found at http://www.swlearning.com/economics/mceachern/economist.html). Two studies published in July 2002 suggest that sleep helps reinforce new learning. Sara Mednick and her colleagues at Harvard examined the role of sleep in perceptual learning. Subjects were taught a task in the morning, but their performance deteriorated throughout the day. A 30-minute nap halted that slide and a one-hour nap boosted performance to its best morning levels. The researchers conclude that the deep, slow-wave sleep that occurs during even short naps allows recently learned information to be processed and prepares the mind for new learning. (See Mednick et al., "The Restorative Effects of Napping on Perceptual Deterioration," Nature Neuroscience, July 2002, pp. 677-681.)
In the second study, Matthew Walker and his collaborators at Harvard trace the effects of sleep on learning motor skills. In the morning subjects were taught to punch a sequence of keys, after which they practiced at length and were tested. When retested later that same day, their speed and accuracy had not improved. If, however, subjects were taught the task in the evening, then retested the next morning after a good night's sleep, their performance improved an average of 20%. Sleep seemed to reinforce and enhance new learning. Walker speculates that the sleep demands of new learning may help explain why babies sleep so much. (See Walker, et al., "Practice with Sleep Makes Perfect: Sleep-Dependent Motor Skill Learning," Neuron, 3 July 2002, pp. 205-211.)
Newsweek's cover story "In Search of Sleep" (15 July 2002) notes that Americans average about seven hours of sleep a night, or 90 minutes less than a century ago. The story argues that the resulting sleep debt translates into higher accident rates on the highway and on the job. Paul Samuelson once wrote, perhaps tongue-in-cheek, that graduate students need at least four hours of sleep a night.