title: The impact of pain on anxiety and depression is mediated by objective and subjective sleep characteristics in fibromyalgia patients.
abstract: OBJECTIVE
  Pain is the cardinal feature in fibromyalgia syndrome (FM) and increases the risk of anxiety and depression. Patients with FM frequently report sleep disturbances as well. Sleep may mediate the association between pain and emotional symptoms, an idea which has been scarcely studied. The objective of this study was to uncover the role of subjective and objective sleep characteristics as mediators of the relationship between pain and anxiety and depression in FM.
  
  
  METHODS
  Fifty-five female with FM (mean age, 47.62 ± 7.64 y) were assessed to obtain self-reported measures of pain, sleep quality, anxiety and depression levels, and self-efficacy to cope with pain. An ambulatory polysomnographic recording was performed to assess sleep architecture.
  
  
  RESULTS
  Subjective poor sleep quality was found in all participtants. Pain correlated with subjective and objective sleep parameters, self-efficacy, anxiety, and, marginally, with depression. The mediated regression analysis suggested that the best models to explain the impact of pain on anxiety and depression included, as mediators, subjective sleep quality, objective sleep efficiency, and self-efficacy (these models explained 34% of the variance), with objective sleep efficiency being the mediator with the highest influence (P<0.05).
  
  
  CONCLUSIONS
  These findings show a high prevalence of sleep problems in individuals with FM and suggest that they play a role in the relationship between pain and anxiety and depression. In fact, the impact of chronic pain on the later emotional variables was mediated not only by self-efficacy but also by subjective sleep quality and, especially, by objective sleep efficiency.
authors.affiliation: *Mind, Brain, and Behavior Research Center †Department of Personality, Assessment, and Psychological Treatment, University of Granada, Granada, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Diaz-Piedra
authors.forename: Andres
authors.initials: A
authors.lastname: Catena
authors.forename: Elena
authors.initials: E
authors.lastname: Miro
authors.forename: Maria P
authors.initials: MP
authors.lastname: Martinez
authors.forename: Ana I
authors.initials: AI
authors.lastname: Sanchez
authors.forename: Gualberto
authors.initials: G
authors.lastname: Buela-Casal
mesh_terms: D000328:Adult; D001007:Anxiety / Q000209:etiology* / Q000523:psychology; D003863:Depression / Q000209:etiology* / Q000523:psychology; D005260:Female; D005356:Fibromyalgia / Q000150:complications* / Q000523:psychology*; D006801:Humans; D008875:Middle Aged; D010146:Pain / Q000209:etiology*; D010147:Pain Measurement; D017286:Polysomnography; D011569:Psychiatric Status Rating Scales; D012044:Regression Analysis; D020377:Self Efficacy; D057566:Self Report; D012893:Sleep Wake Disorders / Q000209:etiology*