Intensive care unit depth of sleep: proof of concept of a simple electroencephalography index in the non-sedated

Table 1 Patient characteristics for the control group and results of R&K analysis (number = 15)

Characteristics	Control group, number = 15
Male/Female, number	8/7
Age, mean (SD), years	42.9 (16.2)
BMI, mean (SD)	28.8 (9.3)
ESS^a score, mean (SD)	8.1 (4)
Average length of PSG, hours	19.9 (1.5)
TST^b, mean (SD), hours:minutes	7:50 (1:02)
Sleep latency, means (SD), minutes	23 (10)
Time spent in each stage, mean (SD), % of TST^b
REM	21 (4)
S1	11 (6)
S2	46 (9)
S3	12 (8)
S4	10 (5)
Sleep efficiency^c, mean (SD), %	93 (5)

^aThe Epworth Sleepiness Scale (ESS) is used to determine the level of daytime sleepiness. A score of 10 or more is considered sleepy, 18 or more is very sleepy. ^bTotal sleep time (TST) is the combined time spent in either sleep stage. ^cSleep efficiency is the ratio defined by the time spent asleep and the time spent in bed. BMI, body mass index; PSG, polysomnography; REM, rapid eye movement; R&K, Rechtschaffen and Kales; SD, standard deviation.

ISSN: 1364-8535