Napping may not be synonymous with summer afternoons but the two are certainly linked by tradition, habit, and the sheer pleasure of the practice. Of course, the same could be said for couch naps on weekend afternoons, or naps atop cool sheets in shuttered bedrooms, or grainy naps under beach umbrellas.
A few societies still have their days organized to include the siesta, that officially approved nap in the hottest part of the day. In much of the world, however, and especially in highly industrialized societies, naps are not socially acceptable. They are seen as a sign of laziness, and to admit to napping is to admit to weakness. But the reason for the strong pull of the afternoon nap lies deep in the brain--in the suprachiasmatic nuclei, a cluster of cells in the hypothalamus where the circadian clock regulates cycles of sleeping and waking. At the time approximately 12 hours from the deepest point of nighttime sleep, this regulator pushes the body to sleep again in the afternoon. A short sleep then gives energy, improves performance, and increases alertness. Even a ten-minute nap has been proven beneficial. Beyond these clearly productive virtues, however, are the well-attested pleasures of the nap, the relaxation and sense of “time out.”
Sleeping and waking are naturally linked to daylight. Industrialization, however, has pushed back the night, with electric light making the 24-hour day not only possible but now common, and with jet travel mixing day and night. Night shifts, midnight supermarkets, late-night TV, and all the rest of well-lighted life has shrunk the time that people sleep. The result may be that most adults now get less sleep than they need, and some sleep so little that they are a danger to themselves and others at work and driving their cars. Some organizations, such as those responsible for airline pilots, police officers, and health professionals, have begun to take naps seriously--either because the naps may be a sign that their employees are sleep-deprived, or because they may improve the well-being and performance of even the rested. While officially approved naps at the office desk or in the new “nap rooms” may not reproduce the pleasure of drifting off in a hammock in the back yard, the restorative effect can be just as great.