Got the ITIS? Take a nap.

Does napping after a meal affect memory formation?

The lion’s share of research has focused on the relevance of longer periods of nocturnal rest. For that reason, the duration that is actually needed for sleep’s effects on memory to become behaviorally relevant has not yet been exhaustively investigated. We have reason to assume, however, that even short periods of rest can indeed improve memory formation.

There are only a handful of studies investigating the effect of a short nap on the consolidation of declarative memories, which involve facts and events. Most of these studies have reported better memory performance after sleep as compared with wakefulness, revealing improvements of 4 to 46 percent in word-pair memory after a nap and a 3 percent loss to a 28 percent improvement after wakefulness. Even an ultrashort catnap of about six minutes resulted in better memory retention than staying awake did, but a longer doze of 35 minutes was clearly superior. Interestingly, a number of experiments have indicated that sleep improves memory regardless of whether it occurs during the night or the day, which further highlights the cognitive potential of a postprandial nap.

Research on procedural memory, which comprises perceptual and motor skills (such as learning to play an instrument), has found that a short siesta of 60 to 90 minutes improves visual perception only if the nap includes both slow-wave and rapid-eye-movement sleep, the two phases that the brain cycles through while we doze. In studies focusing on motor skills, such as those in which subjects were asked to repetitively type certain keyboard sequences, a posttraining nap of 60 to 90 minutes likewise improved finger-tapping performance. Even so, the study participants did not show as much improvement after the nap as they did after the following full night of sleep.

FULL STORY at Scientific American Mind