title: The effect of experimentally induced sedentariness on mood and psychobiological responses to mental stress.
abstract: BACKGROUND
  Evidence suggests a link between sedentary behaviours and depressive symptoms. Mechanisms underlying this relationship are not understood, but inflammatory processes may be involved. Autonomic and inflammatory responses to stress may be heightened in sedentary individuals contributing to risk, but no study has experimentally investigated this.
  
  
  OBJECTIVE
  To examine the effect of sedentary time on mood and stress responses using an experimental design.
  
  
  METHODS
  Forty-three individuals were assigned to a free-living sedentary condition and to a control condition (usual activity) in a cross-over, randomised fashion and were tested in a psychophysiology laboratory after spending 2 weeks in each condition. Participants completed mood questionnaires (General Health Questionnaire and Profile of Mood States) and wore a motion sensor for 4 weeks.
  
  
  RESULTS
  Sedentary time increased by an average of 32 min/day (P = 0.01) during the experimental condition compared with control. Being sedentary resulted in increases in negative mood independent of changes in moderate to vigorous physical activity (ΔGHQ = 6.23, ΔPOMS = 2.80). Mood disturbances were associated with greater stress-induced inflammatory interleukin-6 (IL-6) responses (β = 0.37).
  
  
  CONCLUSIONS
  Two weeks of exposure to greater free-living sedentary time resulted in mood disturbances independent of reduction in physical activity. Stress-induced IL-6 responses were associated with changes in mood.
authors: Romano Endrighi, PhD, Department of Epidemiology & Public Health, University College London, UK and Department of Medical & Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA; Andrew Steptoe, DPhil, Department of Epidemiology & Public Health, University College London, UK; Mark Hamer, PhD, National Centre for Sport and Exercise Medicine, Loughborough University, UK r.endrighi@ucl.ac.uk.
authors: Romano
authors: R
authors: Endrighi
authors: Romano Endrighi, PhD, Department of Epidemiology & Public Health, University College London, UK and Department of Medical & Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA; Andrew Steptoe, DPhil, Department of Epidemiology & Public Health, University College London, UK; Mark Hamer, PhD, National Centre for Sport and Exercise Medicine, Loughborough University, UK.
authors: Andrew
authors: A
authors: Steptoe
authors: Romano Endrighi, PhD, Department of Epidemiology & Public Health, University College London, UK and Department of Medical & Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA; Andrew Steptoe, DPhil, Department of Epidemiology & Public Health, University College London, UK; Mark Hamer, PhD, National Centre for Sport and Exercise Medicine, Loughborough University, UK.
authors: Mark
authors: M
authors: Hamer
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect; D015415:Biomarkers; D018592:Cross-Over Studies; D003863:Depression / Q000097:blood; D015444:Exercise; D005260:Female; D006339:Heart Rate; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D009490:Neurosecretory Systems; D011569:Psychiatric Status Rating Scales; D057185:Sedentary Behavior; D013315:Stress, Psychological / Q000097:blood*; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D015415:Biomarkers; C508600:IL6 protein, human; D015850:Interleukin-6