BMJ Open 2013;3:e002999 doi:10.1136/bmjopen-2013-002999
Are there sleep-specific phenotypes in patients with chronic fatigue
syndrome? A cross-sectional polysomnography analysis
Zoe M Gotts1, Vincent Deary1, Julia Newton2, Donna Van der Dussen3,
Pierre De Roy3, Jason G Ellis1
1Northumbria Centre for Sleep Research, Department of Psychology,
Northumbria University, Newcastle, UK
2Institute for Ageing and Health, Newcastle University, Newcastle, UK
3Fatigue Service, VermoeidheidCentrum Nederland bv, Lelystad, The Netherlands
Correspondence to Dr Jason G Ellis; Jason.firstname.lastname@example.org
Received 5 April 2013
Revised 24 April 2013
Accepted 25 April 2013
Published 1 June 2013
Objectives Despite sleep disturbances being a central complaint in
patients with chronic fatigue syndrome (CFS), evidence of objective
sleep abnormalities from over 30 studies is inconsistent. The present
study aimed to identify whether sleep-specific phenotypes exist in CFS
and explore objective characteristics that could differentiate
phenotypes, while also being relevant to routine clinical practice.
Design A cross-sectional, single-site study.
Setting A fatigue clinic in the Netherlands.
Participants A consecutive series of 343 patients meeting the criteria
for CFS, according to the Fukuda definition.
Measures Patients underwent a single night of polysomnography
(all-night recording of EEG, electromyography, electrooculography, ECG
and respiration) that was hand-scored by a researcher blind to
diagnosis and patient history.
Results Of the 343 patients, 104 (30.3%) were identified with a
Primary Sleep Disorder explaining their diagnosis. A hierarchical
cluster analysis on the remaining 239 patients resulted in four sleep
phenotypes being identified at saturation. Of the 239 patients, 89.1%
met quantitative criteria for at least one objective sleep problem. A
one-way analysis of variance confirmed distinct sleep profiles for
each sleep phenotype. Relatively longer sleep onset latencies, longer
Rapid Eye Movement (REM) latencies and smaller percentages of both
stage 2 and REM characterised the first phenotype. The second
phenotype was characterised by more frequent arousals per hour. The
third phenotype was characterised by a longer Total Sleep Time,
shorter REM Latencies, and a higher percentage of REM and lower
percentage of wake time. The final phenotype had the shortest Total
Sleep Time and the highest percentage of wake time and wake after
Conclusions The results highlight the need to routinely screen for
Primary Sleep Disorders in clinical practice and tailor sleep
interventions, based on phenotype, to patients presenting with CFS.
The results are discussed in terms of matching patients' self-reported
sleep to these phenotypes in clinical practice.