SHOULD WE BE TAKING MORE SLEEP

Reports of reduced daytime sleepiness following extended nighttime sle ep in normal, regular sleepers suggest that they (and perhaps much of the general population) are chronically sleep deprived. However, 1) th e social and environmental contexts of sleep allow for much intraindiv idual variation in sleep duration and structure; 2) animal studies sho w that when there is opportunity for sleep and few incentives to remai n awake, sleep occurs for reasons other than in response to a physiolo gical requirement, i.e. sleep satiation may precede actual awakening, 3) accounts of increased sleep duration earlier this century are flawe d and 4) because increased sleep onset latency and wake after sleep on set are features of extended sleep, it would be difficult to persuade people to sleep longer for the small benefits to daytime alertness. La boratory studies show that 1) following extended sleep the improvement s in daytime alertness are minor, even by the Multiple Sleep Latency T est (MSLT), and could be achieved equally successfully and with less d isruption to habitual daily patterns by taking a short nap; 2) normal subjects extend sleep at night not necessarily because they are chroni cally sleepy, because there may be no prior MSLT signs of daytime slee piness; 3) mood effects of extended sleep are confounded by earlier be dtimes; and 4) extended sleep does not necessarily make subjects feel well rested immediately on waking. In sum, most people are not chronic ally sleep deprived but have the capacity to take more sleep, in the s ame way that we eat and drink in excess of physiological needs.