By Robert Backer
An age-old conundrum continues to confront countless students as they face mounting pressures from school: Should I stay up a little later to study or go to bed, wake up fresh, and tackle this material tomorrow?
Have you ever struggled through a study session before going to sleep, then upon waking, discovered that the material was fresh and deeply embedded in your mind? Conversely, have you ever chosen studying over getting sleep to the detriment of your performance the following day?
Although learning is still possible with a lack of sleep, our brain is programmed to strengthen new memories during (quality) rest. Whether you’re a young student or a retired professional, sleep is the most natural way to fortify your memory. In this article, let’s explore what goes on “under the hood” as our neurons work while we snooze and how sleep impacts both young and old in different ways.
- Memories undergo a process called “consolidation” during sleep, meaning newly acquired information is integrated into long-term memory banks.
- In particular, deep sleep is critical. This is when memories are reactivated so that deeper connections can be made.
- By minding your sleep routine, you can optimize your long-term memory—and more.
How Sleep Affects Memory
Ever wondered what your brain does while you sleep? Let’s give your family something interesting to consider at the dinner table tonight.
A couple of components in the brain are particularly relevant to our discussion. One is the hippocampus, which is responsible for preserving recent memory. If you’re inclined toward computers, you could think of it like your brain’s RAM (random access memory)—it recycles experiences in a buffer to keep them accessible. This kind of memory tends to be vivid, preserving all the sensory details of what physically happened.
Next is the neocortex: This is what you often see when looking at pictures of the brain, as opposed to a core set of smaller regions, including the hippocampus, which is situated in the center of the brain and brain stem. The neocortex is responsible for much of your higher-level sensory processing and storing semantic information like facts and associations.
The temporal lobes (two large areas located on the sides of the brain) store knowledge of facts and associated details, even though you may not remember when you learned these things. So when you are recalling trivia, you can thank your temporal lobes.
During sleep, information is transferred from the hippocampus “buffer” to long-term memory storage in the neocortex. This conversion process is called “consolidation.” Neurons have branches that send and receive electrochemical signals, and part of consolidation involves neurons making new connections between these branches.
‘Slow-Wave’ Brain Frequency Maximizes Memory
Our brain cells relay electrical impulses in oscillations at different frequencies. When cells’ signals are oscillating at the same frequency, it allows them to sync. During sleep, we go through different stages characterized by different frequencies.
Generally, we can think of rapid frequencies as talking between nearby neurons and slower frequencies as entraining large swaths of neurons that may be farther away from one another.
In “deep sleep,” also known as “slow-wave” sleep, the brain enters its slowest delta frequencies (.5 to 4 hertz). This enables larger swaths of neurons to coordinate and is thought to promote long-term consolidation of information. The brain changes its rhythms throughout a night of sleep.
If you want to maximize your long-term memory, quality rest requires time spent in slow-wave sleep because that is where consolidation occurs.
Metabolic Benefits of Deep Sleep
Our immune system also has a kind of “memory.” When foreign pathogens enter the body, immune cells learn to recognize disease through a complex series of biochemical adaptations. This enables the body to produce more antibodies and fight off disease if we are exposed to the same pathogen again later (i.e., supporting acquired immunity).
Just like your brain’s memory is tied to sleep, so is your immune system’s memory. Studies have shown that lack of sleep can actually decrease antibody count following exposure to viral pathogens.
In addition to fighting off disease, the body uses our time asleep to flush out metabolic waste from the brain, a process known as autophagy.
Aging is the most substantial risk factor for dementia. You may have heard of beta-amyloid plaque—a form of protein tangles, the buildup of which is a hallmark of Alzheimer’s disease. Beta-amyloid is usually not a problem for the brain to eliminate during sleep. That’s because, during sleep, the brain transforms. Space between cells widens, allowing toxins and cellular debris to flow out, much like a special sewer system.
Sleep disruption has been shown to increase soluble beta-amyloid plaque, suggesting it can increase Alzheimer’s disease risk.
The relationship between deep sleep and memory changes as we age. Very young children spend a great deal of time in slow-wave sleep stages. For children and younger adults, deep sleep can increase the ability to master learning new material, and missing it can compromise performance. As we age, we spend less time in deep sleep, making quality sleep more critical than ever.
How to Improve Sleep Quality
It’s no secret: Americans are a sleep-deprived bunch. According to recent research, nearly one-third of Americans may not be getting adequate sleep. About a quarter may be insomniacs. While over half of Americans reported that sleep was a “major priority,” we all know it’s not always easy to achieve.
It’s important to note that simply plopping your head on the pillow and sawing wood doesn’t guarantee quality sleep, even if you are getting a solid eight hours. Disruptive factors such as stress, caffeine, alcohol, and exposure to blue light from electronic devices can all interfere with the brain’s ability to achieve deep sleep.
For many of us, getting our z’s can be attainable with simple changes to our daily routines. Some smart tips to consider for securing quality shut-eye include the following:
- Establish a regular sleep schedule. Your body gets used to rhythms. By maintaining a consistent routine, even on days off, you can set your body to go to bed at a certain time. Prepare yourself for winding down and prime yourself to wake up ready to seize the day. Automatically adjusting lightbulbs that mimic sunset and sunrise can be particularly useful.
- Develop a healthy bedtime routine. Establishing cues that it’s time to relax will set you up for success even before you get into bed and try to nod off. Using lavender aromatherapy or taking a warm bath can help you wind down from the daily grind and prepare yourself for rest. Avoid stimulating activities and blue light from electronic devices at least 30 minutes before bed; instead, do something relaxing like reading a book.
- Create a calm sleep environment. Because we are highly sensitive to light, black-out shades or an eye mask can go a long way in helping us fall asleep. Background noise, such as a fan, white noise, or rain sounds, can often buffer pesky intrusions. For others, a nice set of earplugs may make the difference. Finally, consider setting the temperature to be a little cooler before slipping into bed and a little warmer for waking up.
- Watch out for caffeine. If you like to have an afternoon pick-me-up, bear in mind that caffeine has an average half-life of three to five hours, according to the American Academy of Sleep Medicine. The half-life is the time it takes to eliminate half of the caffeine from your body, though the rest can still linger longer. That means that the average person may want to avoid consumption past mid-afternoon. Don’t try to turn your body on and off with coffee or alcohol.
- Avoid alcohol as a sleep aid. While alcohol may relax you at first, it’s also been shown to disrupt your deep sleep quality. Additionally, living life like a yo-yo puts stress on your body’s ability to adapt, as not all systems will be reversed with sleep aids after introducing a stimulant.
- Avoid late eating. When we sleep, digestion slows significantly. Avoid heavy meals before bed, which can burden the digestive system and disrupt a good night’s sleep.
- Nip the napping. Midday naps can be great for improving mental energy, but limiting them to 20 to 30 minutes works with your brain’s sleep stages to help you from going “too deep” and guarding against “sleep inertia” by falling into a drowsier, hangover state. It’s best to nap in the early afternoon to ensure you can fall asleep at night.
- Exercise regularly. Regular exercise relieves pent-up stress and is shown to play a positive role in promoting healthy sleep. It’s best to exercise in the morning or early afternoon so your body has a chance to return to a relaxed baseline before bedtime. Moving throughout the day—standing, walking, doing light cardio or calisthenics (e.g., pushups, jumping jacks), or brief stretches, can also help keep your mind and body balanced and more relaxed when you sleep.
- Tune out distractions. Consider using a technique called “serial diverse imagining.” Simply pick a word and imagine as many things as possible that start with the first letter. For example, choose “sleep” and start with words beginning with “s,” such as snooze. When you run out of ideas, move on to the following letter. Focusing on something neutral can help to redirect thoughts. Listening to a calm, low-stakes lecture or bedtime story can also achieve this effect.
- Clear your mind. Progressive relaxation and yoga breathing techniques can help regulate the mind. Engaging in mindfulness or meditation practice can help redirect thoughts away from worry to focus on the present moment. These have proven health benefits, which is why they’ve been practiced for thousands of years.
Whether you want to be at the top of your game or optimize your long-term cognitive health and memory, sleep is the place to start.