Table 2.

Glossary of sleep and rhythm related terms

Term	Definition
Actigraphy	A measure of wrist movement which can be related to rest/activity or sleep/wake. Simply, one moves one’s wrist when awake and tends to be still when asleep Algorithms that have been correlated to the gold standard EEG are used to distinguish wake from sleep
Circadian	24h or approximately 1 day; coming from the Greek circa (about) and dia (day)
Circadian rhythms	Biological rhythms that take about 24h to complete one cycle. Examples of circadian rhythms would include core body temperature, certain hormones (e.g. cortisol, prolactin), sleep/wake
Chronotherapy	The administration of treatment based on times of the circadian rhythm to optimize treatment effects and outcome
Polysomnogram	A recording of sleep that generally includes measures of EEG (brain waves), EOG (eye movement), submental EMG (muscle tension), respiration, ECG (heart rate), tibialis EMG
Time in bed (TIB)	Total time person spends in bed from lights out to final time out of bed
Total sleep time (TST)	Total time spent sleeping during time in bed
Sleep efficiency (SE)	The ratio of the amount of total sleep time (TST) to the amount of time spent in bed (TIB). SE = TST:TIB. The higher the SE, the better the sleep
Sleep onset latency (SOL)	Time from lights out to first appearance of sleep
Wake time after sleep onset (WASO)	Total time spent awake from sleep onset to final arising time