How Sleep Improves Learning and Memory

Trying to learn something new? Have a big exam tomorrow? New research suggests that sleep plays a pivotal role in your brain’s ability to learn new information. So the next time you have a test, try studying first before getting a good night’s sleep instead of staying up all night cramming. Because sleep improves learning, it is important not to skimp on getting your rest.

Sleep Plays an Important Role In Learning

One of the major explanations for why we sleep is known as the information consolidation theory, which suggests that one of the primary functions of sleep is to process information that has been acquired and stored throughout the day.

“We’ve known for a long time that sleep plays an important role in learning and memory. If you don’t sleep well you won’t learn well,” suggested Wen-Biao Gan, PhD, professor of neuroscience and physiology and primary researcher in a study that explores the mechanisms behind this process.

How Sleep Improves Learning

While experts have long known that sleep is critical for learning and memory, the underlying mechanisms behind this process were not well understood.

The study, published in Science, reveals that sleeping and learning helps promote the growth of dendritic spines. These dentritic spines are tiny protrusions at the ends of neurons that connect brain cells and facilitation the transmission of information across synapses.

“Here we’ve shown how sleep helps neurons form very specific connections on dendritic branches that may facilitate long-term memory. We also show how different types of learning form synapses on different branches of the same neurons, suggesting that learning causes very specific structural changes in the brain,” Gan explained in a press release from the NYU Langone Media Center.

Evaluating the Impact of Sleep on Mice

To study this process, Gan and colleagues utilized mice that had been genetically engineered to express fluorescent proteins in neurons. The researchers were then able to utilize a laser-scanning microscope to illuminate and track the growth of proteins in the motor cortex, revealing the growth of dendritic spines before and after the mice learned how to balance on a spin rod.

The scientists first observed that mice would indeed experience dendritic growth after learning to balance on the spin rods. Next, the mice were divided into two groups. The first group trained at balancing and then slept for seven hours. The second group performed the same training, but stayed awake after for seven hours.

Increased Dendrite Growth In Well-Rested Mice

The results revealed that the mice in the sleep-deprivation group experienced significantly less dentritic growth than those in the sleep group. Interestingly, the type of task that was learned also influenced exactly which dendrites would grow.

The study offers insight into the importance of sleep and the impact it has on learning and memory.

“Now we know that when we learn something new, a neuron will grow new connections on a specific branch,” Gan suggested. “Imagine a tree that grows leaves (spines) on one branch but not another branch. When we learn something new, it’s like we’re sprouting leaves on a specific branch.”

At a Glance:

• Study reveals that deep sleep after learning encourages dendrite growth
• Experts have long known that there is an important link between sleep and learning
• Sleep deprived mice experienced less dendritic growth than well-rested mice after a learning task
• Deep sleep results in actual physical changes in the brain

_References

_{Yang, G., Lai, C. S. W., Cichon, J., Ma, W., Li, W., & Gan, W. B. (2014). Sleep promotes branch-specific formation of dendritic spines after learning. Science, 344(6188), 1173. DOI: 10.1126/science.1249098}

_{Mandler, J. (2014). Sleep afterlaearning strengthens connections between brain cells and enhances memory, NYU Langone scientists find. NYU Langone Medical Center Office of Communications and Marketing.}