Wearable sleep trackers like the Oura have variable accuracy for specific sleep-stage data but are helpful for identifying overall trends.

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.

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.’

The flashing green light on a smartwatch estimates a person's heart rate by measuring the amount of light reflected back to the watch as blood vessels expand and contract.

Doctors weigh in: Are wearable fitness devices useful or just entertainment?

In an age where technology is intertwined with our daily routines, there is an evolving relationship between healthcare professionals and the data gained from our wearable devices. This piece, published on The Verge, explores how doctors view and...

Brain wave-reading earbuds are being used by companies to study workplace performance

Limited safeguards prevent governments from accessing and companies from sharing brain data. Foreign governments may also be developing technology to spy on and potentially disrupt human thoughts.

Similarities between human and animal sleep

Have you ever noticed the wide-ranging differences in sleep between humans and animals? Sleep as a necessity is present amongst all animal species, but the specific patterns of sleep vary widely. Just think of the differences between how an owl, a whale, and a horse might sleep. This helpful resource from the Sleep Foundation explores the relations between human and animal sleep, complete with some fascinating statistics about sleep patterns throughout the animal kingdom!

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!

Do wearables help those with chronic disease?

The integration of wearable technology in healthcare has promised significant benefits for chronic disease management, yet the actual impact remains underexplored. This systematic review published in the Journal of Medical Internet Research...

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.

Delta brain waves happen during deep sleep, while REM cycles resemble being awake

As the brain cycles from wakeful rest to deep sleep, different brain waves emerge. Alpha waves occur during restful waking states, while theta waves can be associated with light sleep and meditation. Delta waves are observed during deep sleep—but REM cycles more closely resemble active awake states.

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.

Neural rhythms shape how we move, focus, remember, and interact with the world

Millions of neurons in the brain produce rhythmic electrical signals, or brain waves, that guide physical movement and help form and store memories. Researchers also use these rhythms to create brain-computer interfaces, letting people control devices using only their thoughts.

Using fitness wearables to track muscle wasting in astronauts

All that exercising, and astronauts still are likely to lose a large amount of muscle mass while in microgravity. Astronauts can lose up to 20 percent of their muscle in as little as five days in space. Currently, tracking muscle loss means waiting until astronauts land to remeasure their muscle density post-trip. This article explains a NASA-backed fitness wearable that may be able to track muscle atrophy as it happens.

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.

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.

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.

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

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.

Five patterns may define how we sleep—not just night owl or early bird.

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.

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.

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 study of dreams, formally called oneirology, has evolved over the centuries, from anecdotal interpretations to advanced brain imaging.

Activity trackers promise to improve health by forcing us to examine the facts

Explore how modern fitness culture, rooted in capitalist ideals of productivity and control, shapes our perception of health and self-worth. The author blends cultural criticism with personal insight to examine the contradictions of the wellness industry, the rise of wearable tech, and what it means to "optimize" a body.

Predictive brain implants raise ethical concerns about patient autonomy after surgery

These devices can accurately forecast neurological events like seizures and suggest or even automatically deliver responses. Their constant monitoring and prescriptive functions may blur the line between patient choice and device influence.

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.

Dream interpretation has evolved from ancient mystical explanations, to dream reports, to tracking electrical activity in the brain and more.

A sleep expert discusses the broad benefits of quality rest

In this three-part series, renowned sleep expert Matthew Walker and doctor Peter Attia explore the role of sleep in memory consolidation and mental health, and the detrimental effects of chronic lack of sleep. The latter has been linked to increased risk of dementia, hypertension, and more.

Four in 10 CPR patients report consciousness not captured by standard measures.

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.

Animal brain studies show brain activity similar to what we'd expect during dreams, but parsing whether animals are truly dreaming depends on how one defines dreaming and how scientists could prove it.

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

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.

How do brain scans work?

There's only one thing in our solar system sophisticated enough to study itself: the human brain. But this self-investigation is challenging because a living brain is shielded by skull, swaddled in tissue, and made up of billions of tiny cells. How do we study living brains without harming their owners? Two experts explain how the various techniques like EEGs, fMRIs, and PETs work in this TedEd talk.

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.

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

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

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.

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.

The dreaming brain, as understood by scientists

Technology has advanced to where the seemingly separate fields of psychology and neuroscience are asking the same questions about dreams, such as whether they're more closely related to perception or visualization. Some field-intersecting findings include research that shows people with impaired face perception don't dream of faces, those with brain legion-related cognition difficulties deal with similar issues in dreams, and children's dreams change in parallel to their cognitive development.

An estimated 1 in 250 people—a small subset of the population—reports they've never remembered a single dream.

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.

People with a sleep disorder called REM Sleep without Atonia don't experience the temporary paralysis of skeletal muscles that typically occurs during REM sleep—instead, they have vivid dreams that they act out during sleep.

We dream for around two hours each night, on average, but the exact purposes of dreams remains under investigation.

Sleepwalking, or somnambulism, is a bit of a misnomer since many things can occur during this state, including speaking, using the bathroom, and more.

The human brain only uses 5% more energy during active tasks versus resting

Despite only being 2% of the weight of a human body, the average adult brain consumes 20% of its energy, with the majority of it spent on maintaining homeostasis—the stable equilibrium conditions of temperature, acidity, blood sugar, and other properties in the body. For infants, the consumption is closer to 50%.

Alternatives to polygraphs, which correctly identify innocent people only 57% of the time

Lie detector polygraphs have been standard in law enforcement for a century despite being based in unproven science. Researchers are exploring brain-scanning and eye-tracking alternatives, though some suggest there's no reliable lie-detection process at all.

Limited battery life and increasing discomfort prevent extensive use of mixed reality headsets

Spending 24 hours wearing Apple's Vision Pro highlights some of the challenges facing MR technology, which are compounded by an increasing number of bugs when software is run in nonideal conditions. However, practical and entertainment benefits include placing multiple midair timers when cooking and experiencing immersive multimedia, such as astronomical flythroughs.

Most things you would get tested for at the doctor’s office are influenced by circadian rhythm

In this video, a Salk Institute Researcher offers daily habit tips focused on aligning with your circadian rhythms. She notes heart rate and blood pressure are highest in the afternoon, for example, and there’s a triglyceride peak in the morning. Generally, she says, it’s a good idea to schedule your doctor’s checkups at the same time of day each year so there’s consistency across your data.

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.