Just How Long Is the Most Effective Power Nap?

March 26, 2015 Updated: January 5, 2017

Power napping for an hour can help you to learn, remember and interpret more efficiently. When I was in high school, I found that I could study best immediately after awakening from at least a 45-minute nap. Only then could I read, study and memorize efficiently. I think this technique will work for almost everybody. Try to nap before having an important interview, writing a report or learning new concepts.

Napping Improves Memory in Adults

Now we learn that sleeping after you have memorized helps you to remember more effectively. Researchers found that sleeping 45 to 60 minutes after a learning task improves memory in adults.Forty-one people were shown a list of 90 single words and 120 unrelated word pairs and asked to learn them, and immediately complete a memory-recall test. Then half of the subjects took a nap averaging an hour, and half watched a DVD. Their memories were tested again. Those who napped were able to recall five times as much as those who watched the DVD. A brain-wave test (EEG) showed that the nappers had a greater number of sleep spindles that are associated with improved ability to memorize. Previous papers by the same group showed that napping after learning also improves memory in infants.

How Lack of Sleep Affects the Brain

The general consensus of research papers shows that sleeping seven hours a night seems to be optimal for adults’ performance on computer-based memory tests and even for the prevention of diabetes. Sleeping longer or less than seven hours is associated with reduced memory performance.

In one study, magnetic resonance imaging (MRI) and memory tests showed that for every hour less than seven hours of sleep, healthy adults over age 55 lose brain size and ability to remember facts. After just two years, each hour of sleep less than seven hours increased loss of brain size by 0.59 percent and memory performance by 0.67 percent. Doctors can measure loss of brain tissue by measuring the increased size of its fluid-filled ventricles. The brain sits in a tight box, the skull, and has sacs of fluid called ventricles in the middle. As brain tissue shrinks, the fluid-filled ventricles enlarge. Faster brain ventricle enlargement is a known marker for loss of brain size and function in older people and is used to predict how rapidly Alzheimer’s disease is progressing in older people.

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1.Neurobiology of Learning and Memory, April 2015;120:84–93