slow-wave sleep

noun

ˈslō-ˈwāv- 

: the phase of non-REM sleep marked by the deepest sleep and the highest levels of delta wave activity with brain and muscle activity significantly reduced, loss of response to external stimuli greatest, and with heart rate and respiration at lowest levels

Note: Sleep time spent in slow-wave sleep is of longer duration during infancy and childhood.

Deep, or slow-wave sleep, when the body secretes human growth hormone, is critical for development and physical repair.

—Melinda Beck

Members of a second group were awakened every time they entered slow-wave sleep, a stage when dreams tend not to occur.

—Sandra Blakeslee

—abbreviation SWS

Examples of slow-wave sleep in a Sentence

Recent Examples on the Web

This is also known as delta sleep or slow-wave sleep and is when sleep gets deep enough to be more restorative. —Bruce Y. Lee, Forbes.com, 22 May 2025

Consuming high-carb meals shortly before bed has been associated with higher blood sugar and reduced slow-wave sleep (SWS), the deepest phase of non-rapid eye movement (NREM) sleep. —Jillian Kubala, Health, 5 Mar. 2025

Some research shows that eating fiber-rich foods before bed is associated with more time spent in slow-wave sleep, a deep sleep phase crucial for growth, memory, and immune function. —Lauren Panoff, Mph, Rd, Verywell Health, 28 Feb. 2025

At the end of each program the participants' gray matter volume was measured through fMRI, and slow-wave sleep activity was measured through EEG. —New Atlas, 11 Feb. 2025

Word History

First Known Use

1964, in the meaning defined above

Rhymes for slow-wave sleep

• asleep
• upkeep
• beep
• cheap
• creep
• deep
• heap
• jeep
• keep
• leap
• peep
• reap

Medical Definition

slow-wave sleep

noun

: the phase of non-REM sleep marked by the deepest sleep and the highest levels of delta wave activity with brain and muscle activity significantly reduced, loss of response to external stimuli greatest, and with heart rate and respiration at lowest levels

Note: Sleep time spent in slow-wave sleep is of longer duration during infancy and childhood.

Members of a second group were awakened every time they entered slow-wave sleep a stage when dreams tend not to occur.

—Sandra Blakeslee

—abbreviation SWS