Ever go to bed with the name of someone or something on the tip of your tongue? You just can’t quite remember it. Then you wake up the next morning, and bang! Mystery solved.

This often happens to me after I watch an old movie on TCM, the Turner Classic Movies cable station. I’ll recognize an actor from the 1930s, won’t be able to come up with his name, and then forget to watch the credits. Ask me who he was the next morning and I’ll blurt out the name without hesitation.

Luckily, sleep extends this beneficial effect beyond movie trivia. Studies show that sleep can enhance memory and learning. And today’s scientists are helping us understand this nighttime tutoring, thanks to advanced brain scanning technology.

Ride the Waves to Better Learning

Playing foreign language tapes while you sleep may not make you wake up saying “Bonjour!” instead of “Good morning!” But learning during the day can be reinforced after you close your eyes for the night. Research shows that brain waves of different frequencies during sleep help consolidate learning in one part of the brain while also building connections among different parts of the brain that improve learning.

Brown University investigators studied the brain waves of subjects who were taught a finger-tapping task somewhat similar to a piano-playing exercise. During sleep, the subjects showed meaningful changes in two types of waves:

1. Sigma waves. Also known as sleep spindles, these are small, rapid waves that are especially present after a muscle movement.
2. Delta waves. These are much slower, deeper waves that are prevalent during deeper sleep.

Sigma waves are thought to strengthen performance in a specific area of the brain, while delta waves may play a role in enhancing communication among different brain regions. In this study, greater changes in the wave oscillations occurred in those who exhibited the most improvement (faster finger speed and more accuracy) after sleeping.

Nodding Off in Class Has an Upside

No one recommends snoozing away during an important lecture. But just a little sleep after hard-core studying can make it easier to recall the facts when you need them.

In college, I once studied for a biology test all night, right up until I could see chirping birds silhouetted against the dawn. When I tried to remember what I’d been poring over for hours, I couldn’t come up with anything. Then I slept for about an hour. When I opened my blue book in class, most of what I needed to recall flew from my head to my pen.

Harvard University researchers investigated the value of napping in a study of subjects who were assigned to work on three tasks: memorizing 60 pairs of unrelated words, solving a maze, and copying a complex figure. All of them were tested on all tasks, then half of the participants were allowed to nap while the other half rested without sleeping. The nappers improved their performance more than the non-nappers did—but only if they had done well on their initial testing. And napping had no impact on those who hadn’t done well earlier. These results support the value of sleep as an enhancement to learning, not a magic bullet.

Even sleeping for a very short time may enhance retention of recent learning. Napping for just six minutes has been shown to improve recall of memorized words, implying that the onset of sleep alone may be enough to help consolidate learning.

Dreams Enhance Learning, Too

Dreams appear to play an important role in learning certain tasks. In another Harvard University study, college students were given one hour to try to figure out a complicated 3D maze-type puzzle. One group was given the opportunity to nap for 90 minutes after the session, while the other group spent the time reading or relaxing.

When the students returned to the puzzle after the break, those who said they’d dreamed about the puzzle while napping showed the greatest improvement. “Although the dreams didn’t actually depict solutions to the puzzle,” noted the Harvard report, “the researchers believe they show how the dreaming brain can reorganize and consolidate memories, resulting in better performance on learned tasks.”

Erratic Sleep Impairs Learning During Formative Years

Adequate sleep is important at all ages but is especially important for children. Indeed, unpredictable sleeping patterns over time can be detrimental to a child’s cognitive development. In a long-term study at University College London, researchers reviewed the bedtimes of more than 11,000 children at nine months of age, then again at ages three, five, and seven years. Toddlers with irregular bedtimes had lower scores on cognitive tests at age seven than did those who had normal sleeping patterns. Cognitive skills in reading, mathematics, and spatial reasoning were compromised, with irregular bedtimes at age three showing the most negative impact.

Duration of Sleep Matters

Can even a small change in sleep patterns affect mental performance? Perhaps so, according to a small study of children aged 8 to 12 published in the Journal of Epidemiology and Community Health. After a week of typical sleep, 32 children were divided into two groups—some went to bed an hour earlier than usual, some an hour later. The following week, the groups were switched. When both of the reduced-sleep groups were tested again, they had lower scores on measures of short-term memory, working memory, and attention.

The bottom line: Sleep plays a vital role in many aspects of learning and memory. So take a nap already! 

Related Article

• Sleep: Our Tireless Protector

Find Out More

• Christopher Bergland, “Neuroscientists Discover How the Brain Learns While We Sleep,” Psychology Today
• “How Sleep Helps Brain Learn Motor Task,” ScienceDaily