WASO
Pronunciation: WAY-so
Also written as: WASO — Wake After Sleep Onset
Wake After Sleep Onset - the total time spent awake during the sleep period after initial sleep onset, measured in polysomnography.
Full Definition
WASO (Wake After Sleep Onset) represents the cumulative duration of wakefulness that occurs between initial sleep onset and final awakening in polysomnography studies. This parameter excludes the initial period of trying to fall asleep (sleep latency) and measures only the fragmentation of established sleep. WASO is calculated by adding all wake epochs that occur after the first epoch of sleep until the final awakening. Elevated WASO values indicate poor sleep maintenance and may suggest sleep disorders, environmental disturbances, or underlying medical conditions affecting sleep continuity.
Usage
Usage note: Always express WASO in minutes and provide context about normal values for the patient's age group.
In Context
- "The patient's WASO of 120 minutes indicated significant sleep fragmentation throughout the night." — Sleep study report
- "WASO improved from 95 minutes to 35 minutes following CPAP therapy initiation." — Follow-up sleep assessment