The most restorative sleep stage characterized by slow brain waves, essential for physical recovery, immune function, and growth hormone release.
FULL EXPLANATION
Deep sleep (also called N3 or slow-wave sleep) is the most physically restorative stage of sleep, characterized by slow delta brain waves. During this stage, blood pressure drops, breathing slows, and the body focuses on tissue repair and growth.
Deep sleep typically occurs more in the first half of the night and decreases with each sleep cycle. It's during deep sleep that growth hormone is released, immune function is enhanced, and memories are consolidated into long-term storage.
WHY IT MATTERS
Deep sleep is essential for physical recovery, muscle repair, immune function, and metabolic health. Insufficient deep sleep is associated with accelerated aging and increased disease risk.
HOW TO IMPROVE
Improve deep sleep by exercising regularly (especially in morning/afternoon), maintaining consistent sleep schedules, keeping the bedroom cool, and avoiding caffeine and alcohol.
NORMAL RANGES
Adults typically need 1-2 hours of deep sleep per night (13-23% of total sleep). Deep sleep decreases with age, from 20% in young adults to as low as 5% in elderly.
RELATED TERMS
REM Sleep
A sleep stage characterized by rapid eye movements, vivid dreaming, and muscle paralysis, critical for memory consolidation and emotional processing.
Circadian Rhythm
The roughly 24-hour internal biological clock that regulates sleep-wake cycles, hormone release, and other physiological processes.
Growth Hormone
A hormone that stimulates growth, cell reproduction, and regeneration, playing key roles in body composition and metabolism.
Sleep Quality
A measure of how well sleep restores and recovers the body, beyond simple sleep duration.
Active Recovery
Low-intensity exercise performed to promote recovery rather than create training stress.
More in Sleep Science
View all →REM Sleep
Well-EstablishedA sleep stage characterized by rapid eye movements, vivid dreaming, and muscle paralysis, critical for memory consolidation and emotional processing.
Sleep Efficiency
Well-EstablishedThe percentage of time spent actually sleeping versus total time in bed, a key indicator of sleep quality.
Sleep Latency
Well-EstablishedThe time it takes to transition from full wakefulness to sleep after getting into bed with the intention to sleep.