Table 1.

Measures of objective sleep continuity and sleep architecture derived from polysomnography data

Measure	Description
Total sleep time (TST)	The number of minutes scored as N1, N2, N3 or REM sleep.
Sleep onset latency (SOL)	The elapsed time from lights out to the first epoch classified as sleep.
Number of awakenings (NWAK)	The number of stage wake occurrences.
Wake after sleep onset (WASO)	Minutes scored as wake from the first epoch of sleep to lights on.
Sleep efficiency (SE%)	Total sleep time (TST) as a percentage of total recording time (TRT) ((TST / TRT x 100) = SE%).
Time in Wake, N1, N2, N3 and REM (%)	Time scored individually as N1, N2, N3 and REM sleep, as a percentage of total sleep time (TST).
REM, N1, N2 and N3 latency (mins)	The elapsed time from lights out to the first epoch of stage REM, N1, N2 and N3 sleep in minutes.

Abbreviations: TST: total sleep time, SOL: sleep onset latency, NWAK: number of awakenings, WASO: wake after sleep onset, SE: sleep efficiency, REM: rapid eye movement sleep, N1: stage 1 sleep, N2: stage 2 sleep, N3: stage 3 sleep