Rapid eye movement, or REM—the rambunctious stage of sleep in which the body moves and the brain dreams—used to get all the attention. But lately researchers have shifted their focus to SWS, or slow wave sleep. During this deepest phase of sleep, brainwave patterns are large and languid.
Studies have found that cues such as odors, sounds or music can be introduced when people are learning something, and then repeated during SWS to reinforce the new knowledge. Those cues can remind the brain of the learning that accompanied them. Research subjects tended to perform more skillfully on memory tests after this system of SWS cues was applied.
Several smartphone apps aim to determine sleep cycles to improve learning and sleep quality, but measurements are still rudimentary, and their effectiveness varies from one person to another.
Apps to Help You Rise and Shine
Alarms wake you in light sleep. Tests determine whether you're awake. Free trial; $2.89 full version.
Alarm Volume gradually increases to wake you gently. Free; for iOS
"Bio-alarm clock" wakes you in lightest sleep. 99 cents; for iOS.
Guided meditation helps you fall asleep; alarm wakes you. $2.99; for iOS, Android,