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Table 3 Selected sleep stage variables in healthy controls and chronic fatigue syndrome patients who were either less sleepy or sleepier after polysomnography

From: Sleep structure and sleepiness in chronic fatigue syndrome with or without coexisting fibromyalgia

  Healthy CFS a.m. less sleepya CFS a.m. sleepiera
Number 26 14 12
Age, years 37 ± 8 39 ± 8 39 ± 8
Body mass index, kg/m2 24.0 ± 4.4 24.1 ± 5.7 25.8 ± 4.7
CES-D score 8 ± 7 20 ± 8b 14 ± 7b,c
Sleep structure    
Time in bed, minutes 453 ± 33 433 ± 41 445 ± 44
Total sleep time, minutes 385 ± 38 350 ± 50b 353 ± 61b
Sleep efficiency, percentage 85 ± 8 81 ± 9 79 ± 10b
Number of arousals per hour 8.3 ± 5.2 4.8 ± 3.7 6.7 ± 6.1
Wakefulness, minutes 52 ± 38 64 ± 33 61 ± 35
Stage 1, minutes 45 ± 19 32 ± 12 34 ± 22
Wakefulness plus stage 1, minutes 96 ± 44 96 ± 34 95 ± 37
Stage 2, minutes 222 ± 34 195 ± 29b 202 ± 38
Stage 3, minutes 30 ± 22 50 ± 20b 41 ± 26
Stage 4, minutes 5 ± 11 13 ± 15 7 ± 15
Slow-wave sleep (stage 3 + 4), minutes 35 ± 26 63 ± 30b 48 ± 37
Stage REM, minutes 83 ± 24 60 ± 18b 69 ± 33
Sleep latency, minutes 16 ± 19 20 ± 20 32 ± 31b
REM latency, minutes 107 ± 49 128 ± 64 126 ± 69
Median duration of sleep runs, minutes 15.6 ± 18.4 10.0 ± 6.7 7.9 ± 3.3b
Likert scale (0–15.5)    
   Sleepiness    
Evening 6 ± 4 12 ± 2b 6 ± 5c
Morning 1 ± 2d 7 ± 4b,d 10 ± 2b-d
   Fatigue    
Evening 4 ± 4 11 ± 3b 10 ± 3b
Morning 1 ± 2d 8 ± 4b,d 11 ± 3b,c
   Pain    
Evening 1 ± 2 8 ± 4b 7 ± 5b
Morning 0 ± 1 6 ± 4b,d 9 ± 4b,c
   Feeling blue    
Evening 1 ± 2 2 ± 3 1 ± 1
Morning 0 ± 0d 1 ± 3 1 ± 3
  1. Values are presented as mean ± standard deviation. aData dichotomized based on difference between daytime and nighttime self-reported ratings of sleepiness (P < 0.05, analysis of variance [ANOVA]). bSignificantly different from healthy controls. cSignificantly different from CFS in the a.m. less sleepy group (P < 0.05, ANOVA). dSignificantly different from evening (P < 0.05, paired t test). CES-D, Centers for Epidemiological Study-Depression; CFS, chronic fatigue syndrome; REM, rapid eye movement.