Sleep Disorders Glossary D

Sleep Disorders Glossary - D

Deep Sleep

Deep sleep refers to combined non-REM.

Delayed Sleep Phase Syndrome [DSPS]

Delayed Sleep Phase Syndrome (DSPS) is a circadian rhythm sleep disorder in which the patient's internal body clock is not in sync with the morning-rise / evening-sleep pattern of the majority of adults.

A growing body of evidence suggests that the problem is genetic. DSPS patients may have a severely reduced reaction to the re-setting effect of light on the body clock.

Delta sleep

Delta sleep is also referred as slow wave sleep. It is the term used to describe the 3 and 4 stages of NREM sleep. Deep sleep occurs in these 3 and 4 stages of NREM. In most adults these two stages are completed within the first two 90 minute sleep cycles or within the first three hours of sleep.

Delta waves

Delta waves is a slow brain wave, having a frequency of fewer than six cycles per second, that emanates from the forward portion of the brain and is associated with deep sleep in normal adults. Also called Delta Rhythm or Delta Activity.


Desynchronization is the out of syncing of hormone regulation and digestive cycles. This explains jet lag because lack of sleep doesn

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