Does Sleep Affect Your Memory?

Sleep and memory

Do you remember how you used to be able to remember the birthday of everyone in your family without writing it down? And now, have you recently let your little nephew’s day go by without even a mention? As you age, there are normal gaps in your memory that cause you to become a little fuzzy on certain issues. It’s just part of getting older. But if you’ve noticed a change in the way you’re processing and remembering information, and it’s interfering with your daily life, there may be something else going on. That something else could be that you’re just not getting enough sleep and it’s starting to impact your memory.

The link between sleep and memory has been established for more than a century and the quality and quantity of sleep affects your memory, no matter how old you are.[1] That said, since scientists are not entirely sure how your brain retains memory, the exact relationship between sleep and memory is still being investigated and is not completely understood. What we do know is this: more sleep can mean better memory. Despite the unknowns, the general consensus among scientists is that sleep enhances your brain’s ability to remember information and, therefore, to learn.[2] Conversely, a lack of sleep negatively impacts your ability to secure memories and can interfere with learning. Sleep—and different sleep stages in particular—appear to allow the brain to reprocess newly acquired information into your memory. During this process, memories made during the day are said to be “consolidated,” or crystallized into long-term, stable memories.

Research shows that sleep also has an effect on “motor memories”. Motor memory, also known as procedural memory, refers to the ability to learn physical skills like riding a bike, throwing a baseball, mastering a video game or playing an instrument. Sharp motor memory can help people who are training for a sport or learning new musical pieces on the piano. When you get the right amount of sleep, your skill-based memories become sharper. Motor memories can even benefit from an afternoon nap, which is often dominated by light sleep.

Sleep also improves your recall. Declarative memory refers to the ability to store and recall facts, such as all those dates, places, and events you had to memorize in history class. Research has found that memories of recently learned facts strengthen if sleep occurs between learning and testing. During deep sleep (slow wave sleep), declarative memory appears to be given a particular boost. If you’re a college student, an all-nighter may not be your best strategy! Your ability to recall facts will be greater if you allow yourself a good night’s rest before an exam.[3]

Holiday travel can give you something known as jet lag which can also impede your memory’s ability to work as well as it should. Under the influence of jet lag, your mind and body drift in and out of a haze—a haze sometimes held at bay with stimulants like caffeine—and when it finally comes time to sleep, you crash hard. This fuzzy-headed, fatiguing cycle repeats for a few days until you get “back on track” a few days later. Yet scientific research suggests that “getting back on track” may take longer than you think. A lot longer, sometimes more than 28 days to bring your brain back up to speed after disrupting your circadian rhythm with a time change. That’s almost the same amount of time it takes to work off a sleep debt.

Recently, scientists set out to see if jet lag had any effect on the brain’s ability to learn. In order to exercise more control in their experiment, they used hamsters instead of your typical frequent flyer.[4] Researchers pushed the hamsters’ sleep schedule ahead to simulate jet lag, but they did not restrict sleep. The hamsters got their normal hamster amount of shut-eye every day. What did scientists discover? Under the simulation of jet lag, hamsters performed poorly on tasks that involved memory and learning throughout the experiment, even long after they had been returned to their “normal” time. It’s known that a lack of sleep can affect memory and impair learning. It’s also known that certain types of sleep are responsible for certain types of memory processing and learning. However, it was once assumed that as long as you got enough uninterrupted sleep, your body and brain would continue to function as normal. The poor learning abilities that showed up in the jet-lagged hamsters led researchers to ask “Does our internal biological clock influence certain brain functions associated with our intellect?” Put another way: “Is there a link between circadian rhythm and learning?” In the case of the hamster study, the answer is maybe. Exploration of the effects of circadian rhythms on memory, learning, and cognition are a fascinating and growing area of research and there’s much more to investigate in order to link learning to circadian rhythms, including using humans to try and duplicate this particular study.

There’s a lot to learn about the full implications of circadian function in humans, but there’s already solid research about the effect circadian rhythms have on behavior, regardless of surroundings.[5] For example, botanists have observed that plants that appear to respond to light, like morning glories, are actually working off of an internal clock that tells their blossoms to open or close. Likewise, biologists have noted that marine animals continue to respond to daily tidal changes, even when removed from their normal environment. While science continues to decode the mysteries of circadian rhythm, you can do your sleep and your health a favor by maintaining a consistent sleep schedule that helps keep those rhythms working as they should.

Perceptions are also greatly influenced by the amount of sleep you get each night.  It has been suggested that during REM sleep, the brain processes sensory learning, which can lead to better understanding of the visual, auditory, spatial, and emotional conditions that surround us.[6] Even though sleep can be very beneficial for strengthening memories, it is not a great time for new memories to form.[7] As the body transitions between sleep and wakefulness, the brain’s ability to retain new information shuts down. Case in point: Have you ever woken up late in the morning only to realize that you had turned off your alarm without realizing it? You probably fell asleep again so quickly that your brain had no time to store the memory of the alarm ringing. This may also be the reason why you don’t always remember your dreams, or they tend to fade very quickly in the morning. The transitions between sleep and wakefulness make the formation of new memories a challenge.

There’s no denying the connection between getting proper rest and allowing your memory to work at an optimal level. Shoot for 7 to 8 hours of sleep each night to keep everything functioning properly.

Happy Sleeping and Thinking!

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