Sleep Prophylactic naps

Caldwell JA, Caldwell JL. Comparison of the effects of zolpidem-induced prophylactic naps to placebo naps and forced rest periods in prolonged work schedules. Sleep 1998 21(l) 79-90. 

The data demonstrated a dose-related increase in alertness and performance for both prophylactic sleep and dose of caffeine. As a rough generalization, 2-to 4-hours of prophylactic nap was similar to 150-300 mg of caffeine in the magni-... 

Sleep Values for the 4-Hour Prophylactic Nap and the Sum of the Four 1-Hour Nocturnal Naps... 

MSLT values (proportion of prestudy baseline latency to Stage 1 sleep) for 44iour prophylactic nap and 4 x 1-hour nap groups in Study 3. Significant differences are noted ( ) in the figure. Data from Bonnet and Aland (1994a). 

In summary, these studies have demonstrated the beneficial effect of obtaining additional sleep prior to periods of sleep loss and the additive benefits of caffeine use. Subjects for the studies were healthy young adults who did not report significant daily caffeine use and who were not sleep deprived prior to the beginning of each study. In the real world, of course, it is common that shift workers will suffer fiom both chronic sleep loss and tolerance to caffeine. Such limitations could reduce the beneficial impact of both prophylactic naps and caffeine in applied settings. On the other hand, knowledge of the ability of naps and caffeine to produce baseline levels of alertness across nocturnal work periods when used correctly should allow planners to develop improved sustained work schedules. 

A nap prior to sleep loss (a prophylactic nap) improves performance compared to no nap. Schweitzer, Muehlback, and Walsh (1992) assessed subjects who received a 2-to 3-hour nap before a night work shift (with concurrent sleep loss), and found that although the morning circadian trough was still evident the nap attenuated performance declines. Bonnet (1991) found that subjects who napped before 52-houis of continuous wakefulness performed better and were more alert for up to 24 hours of sleep loss compared to those who did not nap. 

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