Neurobites: Sleep and Memory

Neurobites Quiz:

What aspect of sleep helps to consolidate memories and cement your learning?

a. The quality and quantity of the sleep the night before the learning
b. The deepest stage of sleep – or slow wave sleep
c. Rapid Eye Movement (REM) sleep
d. All of the above

Answer: d.  All of the above

Remember to Sleep On It

The quality and quantity of all stages of sleep, both before learning something new and afterward, affect our ability to remember since sleep helps to consolidate memories. It seems relatively effortless. While you sleep, your brain is strengthening memories formed throughout the day and helping to put new facts and ideas in perspective by making connections with existing knowledge. Sleep is also the birthplace of creativity.

For most of human history, we knew sleep was necessary, but we didn’t know why. In the last decades, science has started to zero in on some of the physiological benefits of sleep. At first, behavioral studies showed that people could better remember things like syllables or word pairs if they slept after learning and before testing. They also found that sleeping 8 hours after practicing procedural tasks (like finger tapping exercises) and studying long lists of words would significantly boost recall. They even found that getting a good night’s sleep helped prepare the brain for the initial formation of memories the next day.

Next, the research started to look at brain wave activity and synapse patterns during sleep. Scientists found that we replay experiences from our day while we sleep as a way of remembering what was important. By studying the brain wave activity of rats learning their way through a maze, it became clear that certain “place cells” were activated and the specific electrical activity of these neurons was recorded. While rats were learning their way through a maze, the specific electrical activity of their neurons was recorded.

A similar thing happens to humans. During slow-wave sleep (when there is little or no dreaming), the hippocampus (important for learning) goes into over-drive sending signals to the cortex relaying the day’s sensory experiences. It seems this is how the brain transfers memories from its temporary storage location in the hippocampus to long-term storage in the cortex. This is memory consolidation.

Every sleep stage fulfills a specific physiological and neurological function, each necessary for the health of the body and mind. Memories about facts, ideas and experiences are solidified during the deepest stages of sleep (Non-REM Stage 3). And during REM, the most active stage of sleep when dreams occur, procedural (like riding a bike or learning a new instrument) and spatial (navigating a new town or even a new website) memories are consolidated. It is also during REM sleep that new memories are linked together with related existing memories and connections are made. Sometimes, the links are unexpected and a flash of creativity results. That’s why getting a full night of sleep is helpful in problem solving and hence the advice, “sleep on it.”

Many questions about sleep still remain to be answered. We hope the scientists working on them remember to get a full night’s sleep.

 

If you’re not getting a full night’s sleep, consider using the Dreampad.