A sleep expert discusses the broad benefits of quality rest

A deeper walk through of the four stages of sleep

In this TED video, sleep expert Matthew Walker carefully breaks down the sleep stages along with a description of why each is important. He finishes the discussion by examining the consequences of altered or decreased sleep, and why seemingly small alterations in our sleep patterns can have outsized effects.

High-quality sleep is effectively a superpower

Sleep is critical to maintaining healthy biological functions. From restoring energy to consolidating memories, aiding immune system functions and balancing hormone production, optimizing sleep habits are one of the most important ingredients to healthy living.

The brain will attempt to rest itself in periods of chronic sleep deprivation

Skimping on sleep lengthens reaction times and blunts decision-making skills. At a certain point, the brain will try to sneak sleep where it can, shifting sections offline even as you remain awake. Going without sleep raises blood pressure, undermines the immune system, and increases one's risk of dementia.

Poor sleep increases the risk of developing Alzheimer's, and a main reason appears to be that the brain disposes of toxic protein buildup during high-quality sleep.

What sleep is for and why you can’t live without it

Sleep is one of the most important needs that humans have. The body uses sleep as a time of restoration and rejuvenation, as body tissues repair themselves, growth hormones are released, and the process continues. Brain plasticity theorists believe that sleep is also used for the processing and consolidating of new memories.

The brain consolidates memories during sleep

During sleep, the brain appears to process memories from the day and encode them into long-term storage. At the same time, the brain prunes old memories out of the brain that are no longer useful. Understanding this process also sheds light a various neurodegenerative diseases.

Sleep is often viewed individually, when its impact and meaning may be more communal

At any given point, roughly 2 billion people may be asleep on Earth. The typical scientific description of sleep focuses on its individual impact, but the phenomenon shapes whole cultures and eons. This essay prompts a fresh rethinking of the importance of sleep for humanity.

Your brain moves through four distinct sleep stages every night

Each stage plays a key role in memory, repair, restoration, and other key biological functions. The full cycle generally proceeds from light sleep and deep rest into vivid REM dreaming, which repeats between three and five times nightly.

Explore a series of bedtime exercises to improve sleep

Low-impact, mindful movements can potentially help the body and mind relax before sleeping. Such exercises could be a helpful complement to regular exercise during the day.

Hotels around the world now offer packages focused especially on sleep

A Belmond Hotel in London, for example, has partnered with a meditation and holistic coach to create a service called the Sleep Concierge, which includes meditation recordings, a pillow menu, and the option of a weighted blanket, among other customized options. Medical experts believe that hotel experiences such as this one can be beneficial to those lacking sleep, provided certain provisions (such as an on-call medical professional) are also provided.

Cerebrospinal fluid flushes waste from your brain during sleep, performing a nightly brain cleanup that's an important purpose of sleep.

Obsessing over sleep metrics leads to worse sleep quality

Over one-third of Americans have used wearable technology to track their sleep, and the anxiety over having perfect sleep data, or orthosomnia, has made getting a good night's sleep more difficult. Experts agree that most devices cannot correctly assess sleep details, making the data unreliable.

Studies suggest when you sleep is as important as how much you get.

The evidence for the best sleep positions

For a behavior so crucial to human health, sleep positions are reportedly understudied by researchers. This article summarizes some of the more recent studies, taking into account the various forms of problems encountered during sleep: neck and back pain, snoring, acid reflux, and facial skin damage. Most studies point to side-sleeping as the most optimal, with sleeping on one's front as the least helpful. Read the piece to see which position is best for you.

How dreams affect your memory

In 1999, scientists conducted a study in which participants were asked to recall images flashed before them for milliseconds. They found that participants who slept before recalling the information performed better than those who had been asked to recall the same information that same day. This was some of the earliest convincing evidence of how crucial sleep is for learning and memory, findings that current research continues to strengthen.

Sleeping on a problem does seem to help—in fact research published in 2026 suggests scientists can seed people's dreams with sound cues about a difficult puzzle during REM sleep and they'll be better able to solve it.

What it's like to live with insomnia

The biological process Shakespeare referred to as the chief nourisher of life's feast is necessary for the body and mind to rest and repair from the activities of daily life. As sleep evades the exhausted, sufferers also lose emotional stability, mental clarity, social connections, and more while simultaneously gaining waves of interrupted biological processes that can lead to disease and death.

What happens when we sleep

Sleep is a highly specialized and complex process that begins via signals from a region of the brain called the hypothalamus. As explained in this overview video from The Economist, the hypothalamus maintains our circadian rhythm by using light cues from our environment to regulate sleep via a compound known as melatonin. Once asleep, the brain begins the "sleep cycle" and progresses through the four stages of sleep over and over again each night.

Sleep is no longer considered a binary state—scientists are seeking to map a variety of liminal states between sleep and waking, including the hypnagogic state associated with boosts of creativity.

The benefits of power napping

Research shows it may not be beneficial to fight that mid-afternoon drowsiness: Power naps can make you more alert, reduce stress, and improve your cognitive function.

Olympians view sleep as a performance tool, prioritizing routine and environment

Elite athletes emphasize consistent sleep routines, dark and cool environments, the well-placed nap, and tools like eye masks, white noise machines, and supplements like melatonin (particularly for jet lag). This priority belies a core principle: recovery and performance are inseparable. Read more ways Olympians "sleepmaxx" here.

Emerging research suggests that cannabis, used by about 9% of American adults as a sleep aid, may suppress rapid eye movement and lead to worse quality sleep and fewer remembered dreams.

Sleep research published in 2021 confirmed that there is a 'creative sweet spot' when people are drifting off to sleep, and that if they wake up at that point to work, it can boost their creative problem-solving.

Understanding the stages of sleep

Do you have trouble keeping the different stages of sleep straight and organized in your mind? Us too. Sometimes it helps to have a straightforward listing of what each stage is and why it’s important. Look no further than this resource from Lumen. It is a basic outline of the four stages of the sleep cycle, along with the brainwaves and attributes that characterize each. If you’re brave enough, test yourself on the built-in quiz!

Sleep disorders can exacerbate neurological and other health conditions

Brain regions that control sleep sit adjacent to those that regulate the autonomic nervous system, which controls involuntary bodily functions like heart and breathing rates. These neighbors influence each other, meaning poor sleep can impair or negatively impact the ANS, further disturbing sleep.

Do sleep-tracking apps work?

Can technology help us sleep better? As wearables and apps promise to optimize our nights, this New York Times investigation reveals some troubling findings after columnist Brian Chen used a wearable for two weeks to track his sleep. He discovered that sleep trackers not only provide frequently questionable data but can also paradoxically worsen sleep problems by causing users to obsess over their metrics — a new condition researchers are calling ‘orthosomnia.’

There is a best way to wake up—but not a best time

Sleep and circadian rhythm researchers say that waking up at a consistent time each day—even on weekends—and viewing morning sunlight are the best ways to keep body functions running at their peak. (Some users may encounter a paywall.)

The US loses roughly $400B a year in productivity due to sleep deprivation

For an article about a woman who built a business empire telling bedtime stories, the Hustle created this graphic showing the estimated GDP loss associated with chronic insomnia. The United States had a much more significant loss than other countries.

Forty to 110 minutes of deep sleep is recommended per night

Adults typically spend 10% to 20% of the night in deep sleep, also known as slow-wave sleep, with the rest of the night spent either in light sleep or REM states.

Sleep apnea explained

While sleep apnea is directly tied to an increased risk of cardiovascular and metabolic health problems, many affected people are unaware of their problem. Sleep apnea occurs when upper airway muscles relax during sleep and pinch off the airway, which can cause breathing to pause for 10 seconds or more at a time. Sleep partners (rather than those inflicted) are often the first to notice breathing pauses or loud snoring in their bedmates.

During dream sleep, the brain connects new information learned during the day with information already stored in the mind, creating a revised mind-wide web of associations.

Consistency and emotional engagement can improve the formation of memories

While sleep lets the brain re-trigger neurons associated with our experiences to cement them in long-term memory, repeating actions, like storing one's keys in the same location, can mimic these benefits. Emotionally charged memories are often ruminated upon, improving their future recall.

Watch a USA Memory Champion answer questions about memory

Six-time USA Memory Champion, Nelson Dellis, answers popular questions about memory, from how sleep, stress, emotion, and attention influence memory to ways techniques like the memory palace, mnemonics, and the PAO system can dramatically improve recall.

External factors, not aging itself, lead to sleep loss in older adults

Though it is often believed that people need less sleep as they age, the recommended sleep guidelines for all adult age groups are almost identical. However, factors such as medication use, lack of physical activity, and loneliness can lead to sleep problems, and thereby lead older people to believe that they actually need less sleep than they do.

What sleep loss does to the brain

Proteins in the brain perform various critical functions, such as helping neurotransmitters function or enabling electrical activity in the organ. These proteins must fold in specific ways to perform their duties, similar to paper airplanes. Sleep deprivation contributes to the gathering of misfolded proteins that aren't shaped correctly for their roles and so accumulate in undesired spaces, such as in the gaps between neurons.

Genetics play a role in the reliability of the body's biological clocks

Growing evidence suggests genetics influence when, how long, and how well one sleeps, meaning insomnia may have a genetic component. While exact insomnia biomarkers have yet to be determined, some genes, including those related to psychiatric disorders, have been implicated.

Sleep training: risks and benefits

Sleep training, which can range from implementing a nighttime routine to letting your baby cry it out, is controversial, but does it work? While dozens of studies have found sleep interventions to be effective, it appears that many of these studies...

The overlooked physical causes of insomnia

Persistent lack of sleep is dangerous for anyone, but women are especially unlikely to have their symptoms taken seriously. This article highlights the physical causes of insomnia—a condition often written off as solely psychological—and the importance of early diagnosis. The writer, Courtney Maum, was diagnosed with an anterior nasal valve collapse as the source of her insomnia.

Sharp wave ripples in the brain tag experiences for long-term memory storage

These ripples were known to quickly replay neuronal sequences during sleep for consolidation. While awake, they help the brain prioritize memories to remember, and their disruption can impair memory formation.

Exercise improves brain blood flow, stimulates neural growth, and more.

Scientists are learning to guide your dreams using sound and touch.

Sitting 10+ hours per day increases dementia risk

People who sit for at least 10 hours per day are more likely to develop dementia, according to a study published in 2023. This article details the study on the murky relationship between brain health and prolonged sitting. This study involved...

The side effects of falling back and springing forward

Daylight saving time can interfere with a person’s sleep schedule, but it also has been linked to increased rates of depression, heart attack, stroke, cancer, and car accidents. UT Southwestern’s Dr. Joseph Takahashi explains why the time change is bad for your brain and health.

A quick technical overview of insomnia

Insomnia is one of the world's most common sleep disorders. Characterized by difficulties falling and staying asleep, long-term struggles with insomnia can prelude or contribute to health difficulties. Treatments range from sleep hygiene management and relaxation therapy, and medication, including antidepressants and melatonin.

Sleep deprivation may slow metabolism

This article explains that, according to research from Penn State, restricting sleep for just a few days can affect how the human body metabolizes fats and change how satisfied people feel after a meal. The study found that people who don’t get...

Why do dreamers twitch?

This thought-provoking piece highlights newer research suggesting sleep twitches may not be random dream leftovers, but instead a crucial way our brains map and understand our bodies. From sleeping rat pups to dreaming octopi, this biological mapping system appears universal across animal species.

The REM cycle—named for the 'Rapid Eye Movement' that occurs during this stage of intense dreaming—happens around four to six times per night.

Temperature and certain medications can also affect your circadian rhythms

Although light and dark have the largest influence on circadian rhythms, temperature, stress, and certain medications are among the factors that also play a role. Persistent trouble sleeping or staying asleep may signal it’s time to see your doctor to get a better sleep-wake schedule.

Dreams largely occur during REM sleep (but not entirely).

The body's sleep-wake cycle is one of its many circadian rhythms

The body's sleep-wake cycle is one of its many circadian rhythms, which are behaviors or biological processes that exhibit 24-hour patterns. These rhythms are deeply impacted by light exposure, food availability, and much more, meaning where you live impacts your sleep.