Comparison of subjective and objective measures of insomnia in monozygotic twins discordant for chronic fatigue syndrome.
OBJECTIVE
To examine the objective and subjective measures of insomnia in chronic fatigue syndrome (CFS).


METHODS
Monozygotic co-twin control study.


METHODS
Academic medical center.


METHODS
Twenty-two pairs of monozygotic twins where 1 member of the pair had CFS and the other did not.


METHODS
N/A.


RESULTS
Twenty-two CFS-discordant twin pairs completed a Sleep Disorders Questionnaire, overnight polysomnography, and a postpolysomnography sleep survey. Mean and percent differences in the sleep measures were compared between the CFS and healthy twins using matched-pair methods of analysis. Compared with their healthy co-twins, the CFS twins more frequently endorsed 8 subjective measures of insomnia and poor sleep (all p < or = 0.05). However, the CFS and healthy twins did not differ in objective polysomnographic measures of insomnia, including sleep latency, total sleep time, sleep efficiency, arousal number, arousal index, hypnogram awakenings, rapid eye movement (REM)-sleep latency, and percent stages 1, 2, and 3-4 (delta). Percent stage REM sleep was increased in the CFS twins compared with the healthy twins (27.7% vs. 24.4%, p < or = 0.05). On the postpolysomnography survey, CFS twins reported that they had slept fewer hours (6.2 vs. 6.7; p < or = 0.05), and were less well rested (p < or = 0.001) compared to their co-twins.


CONCLUSIONS
CFS patients had worse subjective sleep than their co-twins despite little objective data supporting this discrepancy, suggesting they suffer from an element of sleep-state misperception. The higher percentage of REM sleep in the CFS twins implies that REM sleep may play a role in this illness.
Department of Neurology and Sleep Disorders Center, University of Washington, Seattle 98104-2499, USA. nwatson@u.washington.edu
Nathaniel F
NF
Watson
Vishesh
V
Kapur
Lester M
LM
Arguelles
Jack
J
Goldberg
Douglas F
DF
Schmidt
Roseanne
R
Armitage
Dedra
D
Buchwald
D000328:Adult; D015673:Fatigue Syndrome, Chronic / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D019964:Mood Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D017286:Polysomnography; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D012895:Sleep, REM / Q000502:physiology; D011795:Surveys and Questionnaires; D014430:Twins, Monozygotic / Q000235:genetics*