More surprising ways naps improve your health
Naps boost your memory and creativity.
It's crazy to associate napping with laziness. A 2010 study at the University of California, Berkeley found that the brain loses some ability to absorb new information over the course of a normal day, but a nap can reverse this decline. Sleep -- including napping -- helps transfer memories from their temporary hold in the brain's hippocampus locations to more permanent storage in the neocortex. Other studies have linked naps to improved performance on memory tests and word-recall tests.
Naps as short as six minutes and as long as 90 minutes have been shown to provide cognitive boosts. In one study, naps of 60 to 90 minutes improved perception skills to the same degree as did eight hours of sleep.
Napping long enough to dream is especially useful for processing and storing information. A study at Boston's Center for Sleep and Cognition at Beth Israel Deaconess Medical Center found that students who trained on a maze task and then took a 90-minute nap performed better on a later maze test than those who had stayed awake. Dreams help the brain make connections you might not have noticed when conscious.
How to benefit: Nap short to refresh, nap long to rethink.
A study in the journal Sleep pointed to the 10-minute "power nap" as the optimal length for recharging cognitive performance without feeling groggy afterward. But for creative thinking and major memory consolidation, you want to cycle though all five sleep stages, which requires a 60- to 90-minute nap. (It's different for everyone, but after about 30 minutes, humans tend to transition into deep sleep, which can be hard to wake from and will leave you feeling even more tired, a transitional state known as sleep inertia.)
Naps improve alertness, keeping you safer.
Lack of sleep is associated with more accidents for drivers and shift workers. Even the nuclear accidents at Chernobyl and Three Mile Island, the Exxon Valdez oil spill in Alaska, and the explosion of the space shuttle Challenger have been partly blamed on sleep deprivation, according to the Harvard Medical School Division of Sleep Medicine.
Napping, on the other hand, can improve alertness, motor dexterity, accuracy, and judgment, studies have shown. A NASA study on sleepy military pilots and astronauts found that a 40-minute nap improved performance by 34 percent and alertness by 100 percent, according to the National Sleep Foundation. Another study, in the journal Sleep, compared naps of different lengths; the 10-minute "power nap" came up the winner for adding alertness without making you groggy afterward.
How to benefit: Try combining naps and caffeine.
Comparative studies have found that drinking caffeine immediately before a 20-minute nap raises alertness for sleepy drivers more than either caffeine or sleep alone (and more than rolling down the window and singing to the radio). That's because it takes up to half an hour for caffeine to kick in -- so after your nap, you get an extra jolt of alertness when the caffeine boost hits. Other research has found that combining a nap before shift work with caffeine consumed during the shift can reduce accidents and other impairments in performance.