We live in a society in which getting by on just a few hours’ sleep is considered a badge of honor. People proudly swap stories about burning the candle at both ends, trying to outdo each other with just how big their sleep deficiency is. Knowing what we know about the importance of high-quality, plentiful, regular sleep—not just for mental focus but for overall health—bragging about being chronically sleep-deprived is a bit like boasting that you’re a chain-smoker or that you never exercise. Simply changing your sleeping habits could prove the single-most important step for improving your concentration, yet at least a third of Americans don’t get the minimum amount of nightly sleep (seven hours) recommended by the American Academy of Sleep Medicine and the Sleep Research Society.

How Sleep Helps

Exactly what happens to our minds and bodies during sleep, including at the cellular level, remains somewhat mysterious to researchers. But we know that sleep is crucial to a staggering number of physiological processes. Tissue growth, cellular repair, immune processes and healing all depend on sleep. We know that a person’s overall health will rapidly deteriorate with significant sleep deprivation.

Besides the physical processes that play out at night, many aspects of mental processing are also closely tied to sleep. During deep, restful sleep, the brain is hard at work doing much of its “housekeeping,” putting the finishing touches on sorting and filing the information you’ve gathered during the day. If you’re trying to learn French, for example, you do the heavy lifting as you watch videos, learn grammar, and practice with flash cards. But those automatic nocturnal processes are what solidifies the information in your brain.

Research is still ongoing into exactly by what mechanisms sleep helps with memory and cognition. But it’s helpful to think of the process of committing new information to memory as occurring in three steps. The first is encoding or obtaining the information from the world around us. The second is consolidation, the stabilization and storage of the new memory.  And the third is recall, the pulling of the information from storage as needed. Encoding and storage both happen during our waking hours, but evidence suggests that the crucial consolidation process happens while we’re sleeping. The types of brain waves that occur during sleep appear to shift new information from the unconscious to the conscious parts of the brain, transforming it from mere information into knowledge.

Brain Health

Sleep helps with more than just long-term memory. Your basic brain function, including short-term memory, is hindered by lack of sleep. To stick with the example of learning French, the daytime work of learning new vocabulary is more difficult if you’re sleep-deprived.

It’s also during sleep that cerebrospinal fluid enters the brain to clear away toxins, such as amyloid plaque and tau, which, when they accumulate, disrupt cognitive function. Chronically insufficient sleep is thus considered a risk factor for Alzheimer’s disease.

Throughout the course of a long day, as your brain becomes increasingly overtaxed by cognitive demands, an interesting change occurs in your brain. The synapses, or gaps between brain cells across which cognitive signals must pass, become wider. While you’re sleeping at night, they return to normal size. After a good night’s sleep, we awake feeling rejuvenated and sharper minded. It stands to reason, then, that a sleep-deprived person might not be giving their brain enough time for the synapses to recover and will thus be operating at a cognitive disadvantage.

There’s reason to believe that neurogenesis, the production of new brain cells, also occurs primarily while we’re sleeping. Until relatively recently, scientists believed that human brains stopped generating new brain cells after childhood. Today, we know that new neurons are created throughout our entire lifetimes. Perhaps related, the brain’s ability to respond and adapt to changes (called “neuroplasticity”), also appears to be strengthened during sleep.

Getting plenty of sleep helps us to regulate our emotions. We get cranky or weepy when we’re exhausted, which makes it hard to focus, hard to concentrate, and hard to commit things to memory. Our judgment, decision-making and reaction time also suffer from lack of sleep, which is why pilots and truck drivers are required to limit the number of hours they work before resting. Imagine trying to focus on an unfamiliar, complex task or idea when you’ve gotten less sleep than is legal for a truck driver to be on the road. The amount of sleep you’ve been getting should be the very first thing that crosses your mind when you’re looking to boost your concentration.

Sleep Phases

During the night, you pass through the following stages of sleep:

Sleep Phases and Cognition

Stage 1Transition to sleepSlowed heartbeat, breathing and eye movement. Muscles relax.
Stage 2Light sleepLowered body temperature. Brain begins to transform information into memories.
Stage 3Deep sleepAssociated with recuperation and improved learning and retention.
Stage 4REM (rapid eye movement) sleepMuscles relax while heartbeat and breathing quicken. Dream phase of sleep.

Sleep Deprivation

Because the brain is so difficult to study, much of what we know about sleep and cognition comes not from analyzing the functioning of healthy brains but from observing the negative cognitive effects of sleep deficiency.  Research over the past 20 years suggests that the integrity of the hippocampus, the brain area most closely associated with memory function, deteriorates when we are chronically deprived of sleep.

Cognitive performance clearly suffers when we’re short on sleep, as is evident to most people through their lived experience. Insufficient sleep not only makes it harder to remember pieces of information, but also makes us more likely to commit incorrect or false information to memory. And the less sleep we get, the harder it becomes to regulate our emotions. Good morale and a positive mindset are keys to succeeding at cognitive tasks. If you’re trying to focus on a cerebral challenge or learn something new, it’s much more difficult if you’re easily frustrated or grumpy. Even leaving aside concentration and focus, poor sleep is implicated in a host of serious medical conditions, including diabetes, high blood pressure, obesity, heart disease, early mortality and stroke. That’s why people concerned about their general wellbeing—and especially those looking for a boost to their concentration and focus—should attend to any sleep issues as a first step toward taking control of their health.

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