slow (delta) wave sleep (stage 4)

Introduction

Deep sleep. EEG dominated by delta waves.

Epidemiology

• slow wave sleep is most prominent during childhood & decreases sharply at puberty
• after age 30, there is a progressive, nearly linear decline in slow wave sleep with age
• in young healthy adults, slow wave sleep predominates in the 1st 1/3 of night & comprises 15-25% of total nocturnal sleep
• in otherwise healthy elderly individuals, especially men, slow wave sleep may be completely absent

Pathology

• disturbance in slow-wave sleep is implicated in cognitive impairment (disorder of working memory) in patients with Parkinson's disease
• atrophy in the medial prefrontal cortex with normal aging leads to less slow-wave sleep, which impairs medial prefrontal cortex to hippocampus connectivity leaving episodic memory stuck in the hippocampus instead of being transformed into more-stable long-term memory
• disruption of slow-wave activity leads to higher CSF A-beta & CSF tau

Physiology

• prior sleep deprivation increases the intensity & amount of slow wave sleep

Diagnostic procedures

• identifed by polysomnography

More general terms

• non-REM sleep

Additional terms

• delta sleep-inducing peptide
• EEG delta rhythm (wave)