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

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

	Healthy	CFS a.m. less sleepy^a	CFS a.m. sleepier^a
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 ± 8^b	14 ± 7^b,c
Sleep structure
Time in bed, minutes	453 ± 33	433 ± 41	445 ± 44
Total sleep time, minutes	385 ± 38	350 ± 50^b	353 ± 61^b
Sleep efficiency, percentage	85 ± 8	81 ± 9	79 ± 10^b
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 ± 29^b	202 ± 38
Stage 3, minutes	30 ± 22	50 ± 20^b	41 ± 26
Stage 4, minutes	5 ± 11	13 ± 15	7 ± 15
Slow-wave sleep (stage 3 + 4), minutes	35 ± 26	63 ± 30^b	48 ± 37
Stage REM, minutes	83 ± 24	60 ± 18^b	69 ± 33
Sleep latency, minutes	16 ± 19	20 ± 20	32 ± 31^b
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 ± 3.3^b
Likert scale (0–15.5)
Sleepiness
Evening	6 ± 4	12 ± 2^b	6 ± 5^c
Morning	1 ± 2^d	7 ± 4^b,d	10 ± 2^b-d
Fatigue
Evening	4 ± 4	11 ± 3^b	10 ± 3^b
Morning	1 ± 2^d	8 ± 4^b,d	11 ± 3^b,c
Pain
Evening	1 ± 2	8 ± 4^b	7 ± 5^b
Morning	0 ± 1	6 ± 4^b,d	9 ± 4^b,c
Feeling blue
Evening	1 ± 2	2 ± 3	1 ± 1
Morning	0 ± 0^d	1 ± 3	1 ± 3

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.

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