Djupsömns

Djupsömns is the Swedish term for the deepest stage of sleep, typically equated with slow-wave sleep in the non-REM portion of the sleep cycle. In English-language literature, the equivalent term is deep sleep; djupsömns appears mainly in Swedish medical and educational texts.

Djupsömns corresponds to non-REM stage N3. It is marked by high-amplitude delta waves on EEG, reduced metabolic rate, and low autonomic arousal. It tends to occur predominantly in the first half of the night and decreases across the sleep period.

Physiology and timing: During djupsömns, cortical neurons exhibit slow, synchronized delta activity; body temperature is lowered; heart rate and breathing are slower; the general level of brain activity is reduced, with certain networks remaining involved in memory processing.

Functions: Deep sleep is associated with physical restoration, growth hormone release, and the consolidation of declarative memories. It may also involve synaptic downscaling and clearance of metabolic byproducts from the brain.

Clinical relevance: Diminished deep sleep is linked to aging and several sleep disorders, including insomnia and sleep apnea. Assessment is typically done with polysomnography. Treatments focus on sleep hygiene, cognitive-behavioral therapy for insomnia, and addressing underlying conditions; some medications can alter deep-sleep duration.

See also: Slow-wave sleep; Non-REM sleep; Sleep architecture.