title: Subjective but Not Actigraphy-Defined Sleep Predicts Next-Day Fatigue in Chronic Fatigue Syndrome: A Prospective Daily Diary Study.
abstract: OBJECTIVE
  This study aimed to (1) examine the relationship between subjective and actigraphy-defined sleep, and next-day fatigue in chronic fatigue syndrome (CFS); and (2) investigate the potential mediating role of negative mood on this relationship. We also sought to examine the effect of presleep arousal on perceptions of sleep.
  
  
  METHODS
  Twenty-seven adults meeting the Oxford criteria for CFS and self-identifying as experiencing sleep difficulties were recruited to take part in a prospective daily diary study, enabling symptom capture in real time over a 6-day period. A paper diary was used to record nightly subjective sleep and presleep arousal. Mood and fatigue symptoms were rated four times each day. Actigraphy was employed to provide objective estimations of sleep duration and continuity.
  
  
  RESULTS
  Multilevel modelling revealed that subjective sleep variables, namely sleep quality, efficiency, and perceiving sleep to be unrefreshing, predicted following-day fatigue levels, with poorer subjective sleep related to increased fatigue. Lower subjective sleep efficiency and perceiving sleep as unrefreshing predicted reduced variance in fatigue across the following day. Negative mood on waking partially mediated these relationships. Increased presleep cognitive and somatic arousal predicted self-reported poor sleep. Actigraphy-defined sleep, however, was not found to predict following-day fatigue.
  
  
  CONCLUSIONS
  For the first time we show that nightly subjective sleep predicts next-day fatigue in CFS and identify important factors driving this relationship. Our data suggest that sleep specific interventions, targeting presleep arousal, perceptions of sleep and negative mood on waking, may improve fatigue in CFS.
authors.affiliation: School of Psychological Sciences, University of Manchester, United Kingdom.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Russell
authors.affiliation: School of Psychological Sciences, University of Manchester, United Kingdom.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Wearden
authors.affiliation: Department of Clinical Health Psychology, Salford Royal NHS Foundation Trust, United Kingdom.
authors.forename: Gillian
authors.initials: G
authors.lastname: Fairclough
authors.affiliation: Centre for Biostatistics, Institute of Population Health, University of Manchester, United Kingdom.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Emsley
authors.affiliation: Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, Sir William Dunn School of Pathology, University of Oxford, United Kingdom.
authors.forename: Simon D
authors.initials: SD
authors.lastname: Kyle
mesh_terms: D056044:Actigraphy; D000339:Affect; D001143:Arousal; D005221:Fatigue / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D015673:Fatigue Syndrome, Chronic / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D011446:Prospective Studies; D057566:Self Report; D012890:Sleep / Q000502:physiology*; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology
keywords: actigraphy; chronic fatigue syndrome; daily diary study; insomnia; sleep