Sleep health

Healthy sleep, sleep disorders, recommended sleep duration, and the relationship between sleep and well-being

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Sleep health

Sleep health describes the quality, duration, timing, regularity, and restorative value of sleep, together with its effects on physical health, mental health, daytime functioning, safety, and overall well-being.

How sleep works · Sleep needs · Mental health · Physical health · Sleep disorders · Healthy habits · When to seek care

Medical notice: Persistent insomnia, loud snoring, witnessed pauses in breathing, gasping during sleep, unusual nighttime behaviors, or excessive daytime sleepiness may indicate a sleep disorder. Healthy habits do not replace appropriate medical evaluation.

◷ Adequate duration Enough sleep for age, health, and individual needs

★ Restorative quality Reasonably continuous sleep followed by refreshed waking

☀ Appropriate timing Sleep aligned with the internal biological clock

↻ Regularity Consistent sleep and wake schedules

Overview

Healthy sleep is more than spending a particular number of hours in bed. It generally includes:

• Sufficient sleep duration
• Appropriate sleep timing
• Reasonably consistent sleep and wake times
• Adequate amounts of non-rapid eye movement sleep and rapid eye movement sleep
• Relatively few prolonged awakenings
• Absence of an untreated sleep disorder
• Restorative waking
• Adequate daytime alertness and function

During sleep, the brain and body remain biologically active. Sleep supports memory consolidation, learning, emotional regulation, immune function, metabolism, cardiovascular health, tissue repair, growth, and development.

The effects of sleep extend into waking life. Adequate sleep supports attention, judgment, reaction time, mood, social interaction, academic performance, occupational safety, and quality of life.

Dimensions of sleep health

Dimension	Meaning	Possible warning sign
Duration	Obtaining enough sleep for age and individual needs	Regularly requiring an alarm despite severe difficulty waking
Continuity	Sleeping without frequent or prolonged disruption	Repeated awakenings, choking, pain, or urination
Timing	Sleeping at a biologically and socially appropriate time	Inability to sleep until very late despite morning obligations
Regularity	Maintaining reasonably stable sleep and wake times	Large weekday-to-weekend schedule changes
Restoration	Waking reasonably refreshed	Adequate time in bed but persistent fatigue or sleepiness
Daytime function	Maintaining attention, mood, memory, and safe performance	Unintended sleep, impaired concentration, or drowsy driving

A person may spend enough hours in bed but still have poor sleep health because of sleep fragmentation, circadian misalignment, abnormal breathing, pain, medication effects, or another condition.

How sleep works

Sleep is regulated primarily by the interaction of two processes:

1. Sleep–wake homeostasis—the biological pressure to sleep increases with time spent awake and decreases during sleep.
2. The circadian timing system—an approximately 24-hour rhythm that influences when sleepiness and alertness occur.

Circadian rhythm

The central circadian clock is located in the suprachiasmatic nucleus of the hypothalamus. Light detected by the retina helps synchronize this clock with the external day–night cycle.

The circadian system influences:

• Sleep and alertness
• Body temperature
• Melatonin production
• Cortisol secretion
• Digestion
• Glucose metabolism
• Immune activity
• Hormone timing

Melatonin generally increases under dim-light conditions in the evening and helps signal biological nighttime. Morning and daytime light help promote alertness and synchronize the internal clock.

Travel across time zones can temporarily separate the internal clock from local time, producing jet lag. Work schedules can create a more persistent conflict known as shift work sleep disorder.

Sleep stages

Normal sleep alternates between non-REM and REM sleep in cycles throughout the night.

N1 sleep

A transitional stage between wakefulness and sleep. Muscle activity decreases, and the person can usually be awakened easily.

N2 sleep

Heart rate and breathing slow, body temperature falls, and responsiveness to the external environment decreases.

N3 sleep

Also called slow-wave sleep or deep sleep. This stage is associated with physical restoration, growth-related processes, and greater difficulty awakening.

REM sleep

Characterized by rapid eye movements, vivid dreaming, altered muscle activity, and important roles in learning, memory, and emotional processing.

Deep sleep tends to be more prominent earlier in the night, while REM periods generally become longer toward morning.

Brief awakenings can occur normally. They become concerning when frequent, prolonged, accompanied by abnormal breathing or behavior, or followed by important daytime impairment.

How much sleep is needed?

Sleep requirements vary according to age, genetics, health, activity, pregnancy, illness, and individual circumstances.

General sleep-duration recommendations per 24 hours

Age group	Recommended amount	Notes
Infants 4–12 months	12–16 hours	Includes naps
Children 1–2 years	11–14 hours	Includes naps
Children 3–5 years	10–13 hours	Includes naps
Children 6–12 years	9–12 hours	Regular schedules support learning and behavior
Adolescents 13–18 years	8–10 hours	Biological sleep timing often shifts later during puberty
Adults	At least 7 hours	Many adults function best with approximately 7–9 hours

These ranges are population recommendations, not rigid requirements for every individual.

An individual may need additional sleep during recovery from illness, accumulated sleep loss, pregnancy, intense physical activity, or other periods of increased physiological demand.

Persistently sleeping longer than expected while remaining unrefreshed can be associated with fragmented sleep, hypersomnia, sleep apnea, depression, medication effects, thyroid disease, neurological illness, or another medical condition.

Sleep debt and social jet lag

Repeatedly obtaining less sleep than the body needs creates a cumulative sleep debt. Sleeping longer on days off may provide some recovery but may not reverse every effect of chronic sleep restriction.

Large differences between weekday and weekend schedules can also disrupt the circadian rhythm. This pattern is sometimes called social jet lag.

Sleep fact: Feeling accustomed to insufficient sleep does not necessarily mean that concentration, reaction time, metabolism, and emotional regulation are unaffected.

Sleep and mental health

Sleep health and mental health have a bidirectional relationship. Psychological distress can interfere with sleep, while inadequate or fragmented sleep can make emotional regulation more difficult.

Sleep deficiency may impair:

• Attention and concentration
• Learning and memory
• Decision-making
• Problem-solving
• Creativity
• Emotional control
• Ability to cope with change
• Interpretation of social cues
• Motivation and social functioning

Sleep deficiency has been associated with depression, anxiety, impulsivity, risk-taking, and suicidal thoughts or behavior.

Depression and sleep

A person with major depressive disorder may experience:

• Difficulty falling asleep
• Frequent awakening
• Early-morning awakening
• Unrefreshing sleep
• Excessive sleep
• Daytime fatigue

Sleep disturbance may be a symptom, contributing factor, or residual problem after other depressive symptoms improve.

Anxiety, stress, and sleep

Anxiety and chronic psychological stress may increase worry, muscle tension, heart rate, and mental arousal near bedtime. Poor sleep can then reduce resilience and make stress more difficult to manage.

This can create a cycle:

Stress or anxiety → difficulty sleeping → fatigue and reduced coping → greater stress

Treatment may need to address both sleep and mental health. Sleep treatment should not be assumed to replace care for depression, bipolar disorder, post-traumatic stress disorder, anxiety disorders, substance-use disorders, or another psychiatric condition.

Mental-health emergency: Anyone experiencing suicidal thoughts, severe confusion, hallucinations, mania, or an inability to remain safe should seek urgent help. In the United States, call or text 988. For an immediate emergency, call 911.

Sleep and physical health

Healthy sleep supports the cardiovascular system, metabolism, immunity, growth, tissue repair, reproductive function, and pain regulation.

Heart and blood vessels

Sleep participates in the regulation of:

• Blood pressure
• Heart rate
• Vascular function
• Inflammation
• Autonomic balance

Chronic sleep deficiency and untreated sleep disorders are associated with hypertension, coronary artery disease, heart failure, cardiac arrhythmia, and stroke.

Metabolic health

Sleep influences:

• Insulin sensitivity
• Blood glucose regulation
• Appetite
• Food choices
• Energy expenditure
• Hormonal signals of hunger and satiety

Chronic sleep deficiency is associated with insulin resistance, obesity, and type 2 diabetes.

Immune health

Sleep supports normal immune responses and regulation of inflammation. Ongoing sleep deficiency may affect the body's ability to respond to infection.

Sleep supports—but does not replace—vaccination, appropriate treatment, nutrition, and preventive healthcare.

Growth and repair

Deep sleep is associated with release of growth hormone, which participates in childhood growth, tissue repair, muscle maintenance, and development.

Sleep also interacts with puberty, reproductive hormones, and fertility.

Pain

Chronic pain and disturbed sleep can reinforce each other. Pain interrupts sleep, while insufficient or fragmented sleep can increase pain sensitivity and reduce coping ability.

Relevant conditions include arthritis, fibromyalgia, migraine, neuropathy, and musculoskeletal disease.

Respiratory health

Sleep changes breathing and upper-airway muscle activity. Disorders such as obstructive sleep apnea, central sleep apnea, asthma, and chronic lung disease may become clinically important during sleep.

Sleep, safety, and performance

Sleep deficiency can cause:

• Daytime sleepiness
• Fatigue
• Irritability
• Slower reaction time
• Reduced attention
• Impaired judgment
• Memory problems
• Reduced coordination
• Increased errors
• Reduced productivity
• Increased risk of injury

Children may show hyperactivity, impulsivity, mood changes, reduced motivation, or declining school performance rather than appearing obviously sleepy.

Microsleep

Microsleep consists of brief, involuntary episodes of sleep during expected wakefulness. A person may not recognize that an episode occurred.

Microsleep is particularly dangerous while:

• Driving
• Operating machinery
• Working at heights
• Monitoring patients
• Flying an aircraft
• Performing safety-sensitive work

Opening a window, increasing music volume, or relying on caffeine does not reliably make severely sleepy driving safe.

Drowsy driving warning: A person struggling to remain awake should stop driving as soon as it is safe and obtain appropriate rest or alternative transportation.

Sleep and overall well-being

Healthy sleep contributes to:

• Emotional resilience
• Social connection
• Academic performance
• Occupational function
• Creativity
• Motivation
• Exercise recovery
• Appetite regulation
• Relationship quality
• Independence
• Overall quality of life

Sleep health is also influenced by the social determinants of health, including:

• Work schedules
• Caregiving responsibilities
• Housing conditions
• Neighborhood noise
• Light exposure
• Financial insecurity
• School schedules
• Healthcare access
• Stress and discrimination
• Availability of a safe sleeping environment

Sleep difficulty should not be described solely as a failure of discipline or willpower.

Common sleep disorders

Insomnia

Persistent difficulty falling asleep, remaining asleep, waking too early, or obtaining restorative sleep despite adequate opportunity.

Possible effects include fatigue, distress, impaired concentration, and mood symptoms.

Obstructive sleep apnea

Repeated narrowing or collapse of the upper airway during sleep, often associated with loud snoring, gasping, or witnessed breathing pauses.

Possible effects include oxygen reduction, sleep fragmentation, cardiovascular stress, and daytime sleepiness.

Central sleep apnea

Repeated interruptions in breathing caused by absent or reduced respiratory effort rather than physical upper-airway obstruction.

Narcolepsy

A chronic neurological disorder affecting regulation of sleep and wakefulness. Features can include sleep attacks, cataplexy, sleep paralysis, and vivid sleep-related hallucinations.

Restless legs syndrome

An urge to move the legs associated with uncomfortable sensations, usually worse during rest and in the evening.

Periodic limb movement disorder

Repetitive limb movements during sleep that may fragment sleep and impair daytime function.

Circadian rhythm sleep–wake disorder

Misalignment between the internal biological clock and the desired or required sleep schedule.

Shift work sleep disorder

Insomnia or excessive sleepiness caused by a work schedule that overlaps the usual biological sleep period.

Delayed sleep–wake phase disorder

Sleep onset and waking occur substantially later than desired, creating difficulty meeting morning obligations.

Parasomnia

Unusual experiences or behaviors during sleep, including sleepwalking, sleep terrors, confusional arousals, and dream enactment.

REM sleep behavior disorder

Loss of normal muscle suppression during REM sleep, potentially allowing a person to physically act out dreams.

Nightmare disorder

Recurrent distressing dreams that produce awakening, sleep avoidance, distress, or daytime impairment.

Hypersomnia

Excessive sleepiness or prolonged sleep despite apparently adequate opportunity for sleep.

NHLBI identifies sleep apnea, insomnia, narcolepsy, restless legs syndrome, jet lag, and circadian disorders among the important conditions studied by sleep researchers.

Obstructive sleep apnea

Obstructive sleep apnea occurs when the upper airway repeatedly narrows or closes during sleep.

Possible signs include:

• Loud habitual snoring
• Witnessed pauses in breathing
• Gasping, choking, or snorting
• Frequent awakening
• Morning headache
• Dry mouth on awakening
• Unrefreshing sleep
• Excessive daytime sleepiness
• Difficulty concentrating
• Irritability
• Frequent nighttime urination
• Sexual dysfunction

Not everyone who snores has sleep apnea, and not everyone with sleep apnea snores.

Risk factors can include:

• Obesity
• Upper-airway anatomy
• Enlarged tonsils
• Advancing age
• Family history
• Alcohol or sedative exposure
• Nasal obstruction
• Certain endocrine and neurological disorders

Possible treatments include:

• Continuous positive airway pressure
• Other positive-airway-pressure devices
• Custom oral appliances
• Weight management when appropriate
• Positional therapy
• Treatment of nasal obstruction
• Selected surgical procedures
• Hypoglossal nerve stimulation in selected patients

In December 2024, the FDA approved tirzepatide, marketed as Zepbound, for moderate-to-severe obstructive sleep apnea in adults with obesity, together with a reduced-calorie diet and increased physical activity.

This treatment does not eliminate the need for appropriate testing or individualized evaluation.

Insomnia

Insomnia may involve difficulty initiating sleep, maintaining sleep, waking too early, or experiencing nonrestorative sleep.

Contributing factors can include:

• Acute or chronic stress
• Anxiety or depression
• Conditioned arousal around bedtime
• Irregular schedules
• Chronic pain
• Menopause-related symptoms
• Medication effects
• Excessive caffeine
• Alcohol
• Another sleep disorder

Cognitive behavioral therapy for insomnia is a recommended first-line treatment for chronic insomnia in adults. It may include:

• Stimulus control
• Sleep scheduling or sleep restriction therapy
• Cognitive techniques
• Relaxation
• Education about sleep
• Relapse-prevention planning

Sleep-hygiene advice alone may not adequately treat established chronic insomnia. Medication may be appropriate for selected patients after consideration of benefits, risks, age, duration, other illnesses, and drug interactions.

Improving sleep health

Healthy sleep practices can support normal sleep and complement treatment for a diagnosed disorder.

Keep a regular schedule

• Maintain reasonably consistent sleep and wake times.
• Limit large weekday-to-weekend differences.
• Protect enough time for sleep.
• Avoid repeatedly sacrificing sleep for optional activities.

Use light strategically

• Seek natural light after waking and during the day.
• Reduce unnecessarily bright light near bedtime.
• Limit screen use when it delays bedtime or increases alertness.
• Obtain professional advice before using timed light therapy for a circadian disorder.

Prepare the bedroom

The sleep environment should generally be:

• Quiet
• Dark
• Comfortably cool
• Safe
• Comfortable
• Associated primarily with sleep and intimacy

Consider caffeine and nicotine

Caffeine and nicotine are stimulants. Caffeine can remain active for hours and may interfere with sleep even when consumed well before bedtime.

Avoid using alcohol as a sleep aid

Alcohol may initially increase sleepiness but can fragment later sleep, worsen snoring, reduce restorative sleep, and aggravate sleep apnea.

Remain physically active

Regular physical activity can support sleep, mood, cardiovascular health, and metabolic health. The ideal timing of exercise varies among individuals.

Develop a wind-down routine

Possible activities include:

• Reading
• Quiet music
• Gentle stretching
• Relaxation exercises
• Meditation
• A warm bath
• Preparing the bedroom

Use naps thoughtfully

A brief daytime nap may improve alertness. Long or late naps may make nighttime sleep more difficult for some people with insomnia.

No supplement, mattress, wearable device, or single “sleep hack” can replace adequate sleep opportunity or appropriate diagnosis of a sleep disorder.

Sleep across the lifespan

Children

Healthy sleep supports growth, learning, behavior, memory, immunity, and emotional regulation.

Sleep-deficient children may appear hyperactive, impulsive, inattentive, or irritable rather than obviously sleepy. Habitual snoring, breathing pauses, unusual behavior during sleep, or persistent daytime difficulty should be discussed with a pediatrician.

Adolescents

Puberty commonly produces a biological shift toward later sleep timing. Early school schedules, homework, employment, social activity, and electronic media may conflict with adolescent sleep needs.

Insufficient sleep can affect mood, learning, athletic recovery, risk-taking, and driving safety.

Pregnancy

Pregnancy can alter sleep because of hormonal changes, nausea, reflux, discomfort, fetal movement, urinary frequency, restless legs symptoms, and sleep-disordered breathing.

New or worsening loud snoring, breathing pauses, severe daytime sleepiness, hypertension, or symptoms of preeclampsia warrant medical attention.

Menopause

Menopause can affect sleep through hot flashes, night sweats, mood changes, and changes in sleep-apnea risk. Insomnia and apnea should be evaluated rather than automatically attributed to aging.

Older adults

Sleep timing and architecture change with age, but severe daytime sleepiness and persistently unrefreshing sleep are not inevitable consequences of aging.

Possible contributing factors include pain, nocturia, medication effects, sleep apnea, restless legs syndrome, depression, neurological disease, and reduced daytime light or activity.

Evaluation and diagnosis

Evaluation of a sleep problem may include questions about:

• Bedtime and wake time
• Time required to fall asleep
• Number and duration of awakenings
• Naps
• Shift work
• Snoring or breathing pauses
• Leg discomfort or movement
• Unusual sleep behaviors
• Daytime sleepiness
• Mood and mental health
• Pain and medical conditions
• Medication and substance use
• Driving and occupational safety

Sleep diary

A sleep diary may record bedtime, estimated sleep onset, awakenings, final waking, naps, caffeine, alcohol, exercise, medication use, morning refreshment, and daytime alertness.

Sleep tests

Depending on the suspected condition, testing may include:

• Polysomnography
• Home sleep apnea test
• Actigraphy
• Multiple sleep latency test
• Maintenance of wakefulness testing
• Blood tests for contributing conditions

Polysomnography may record brain waves, eye movements, muscle activity, breathing, oxygen saturation, heart rhythm, body position, and limb movements.

A home sleep apnea test evaluates selected breathing-related signals. It does not assess every sleep disorder and is not appropriate for every patient.

When to seek medical care

Consult a qualified healthcare professional when:

• Sleep difficulty persists despite adequate opportunity
• Loud snoring occurs with gasping or breathing pauses
• Sleep is regularly unrefreshing
• Sleepiness interferes with work, school, relationships, or driving
• Unintended sleep occurs during routine activities
• Leg sensations repeatedly delay sleep
• Sleep behaviors create a risk of injury
• Sleep problems occur with depression, anxiety, mania, or trauma symptoms
• A child has habitual snoring or learning and behavior changes
• A medication or substance may be interfering with sleep
• Sleep is unusually long but remains unrefreshing

Seek urgent care for severe breathing difficulty, chest pain, stroke symptoms, severe confusion, or an immediate mental-health crisis.

Common misconceptions

Claim	Evidence-based response
“People can train themselves to need almost no sleep.”	Sleep need varies, but most people cannot eliminate the biological effects of chronic sleep restriction.
“Snoring is always harmless.”	Loud habitual snoring with breathing pauses or sleepiness may indicate obstructive sleep apnea.
“Alcohol improves sleep.”	Alcohol can initially increase sleepiness but often fragments later sleep and worsens sleep-disordered breathing.
“Older adults do not need much sleep.”	Sleep patterns change with age, but older adults still require adequate restorative sleep.
“Weekend sleep completely erases sleep debt.”	Recovery sleep may help, but irregular timing may disrupt circadian rhythm and may not reverse every effect of repeated sleep loss.
“Sleep hygiene cures every sleep disorder.”	Healthy habits support sleep but do not replace treatment for apnea, narcolepsy, chronic insomnia, or other disorders.
“More sleep is always better.”	Persistently excessive or unrefreshing sleep may indicate a medical, mental-health, neurological, or sleep disorder.

See also

Sleep science

• Sleep
• Sleep cycle
• Sleep stage
• Circadian rhythm
• Melatonin
• Dream
• Chronobiology

Sleep disorders

• Insomnia
• Obstructive sleep apnea
• Central sleep apnea
• Narcolepsy
• Restless legs syndrome
• Parasomnia
• Hypersomnia

Testing and treatment

• Polysomnography
• Home sleep apnea test
• Continuous positive airway pressure
• Cognitive behavioral therapy for insomnia
• Oral appliance
• Sleep medicine

Health and wellness

• Mental health
• Physical health
• Wellness
• Stress management
• Physical activity
• Preventive healthcare
• Social determinants of health

External resources

• NHLBI Sleep Health
• NINDS: Understanding Sleep
• NHLBI: Sleep Deprivation and Deficiency
• NHLBI: Sleep Studies
• Your Guide to Healthy Sleep

References