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

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


Control group, number = 15

Male/Female, number


Age, mean (SD), years

42.9 (16.2)

BMI, mean (SD)

28.8 (9.3)

ESSa score, mean (SD)

8.1 (4)

Average length of PSG, hours

19.9 (1.5)

TSTb, mean (SD), hours:minutes

7:50 (1:02)

Sleep latency, means (SD), minutes

23 (10)

Time spent in each stage, mean (SD), % of TSTb


21 (4)


11 (6)


46 (9)


12 (8)


10 (5)

Sleep efficiencyc, mean (SD), %

93 (5)

  1. 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.