title: Hawthorne effect with transient behavioral and biochemical changes in a randomized controlled sleep extension trial of chronically short-sleeping obese adults: implications for the design and interpretation of clinical studies.
abstract: OBJECTIVE
  To evaluate the effects of study participation per se at the beginning of a sleep extension trial between screening, randomization, and the run-in visit.
  
  
  METHODS
  Subjects were screened, returned for randomization (Comparison vs. Intervention) after 81 days (median), and attended run-in visit 121 days later.
  
  
  METHODS
  Outpatient.
  
  
  METHODS
  Obese (N = 125; M/F, 30/95; Blacks/Whites/Other, N = 73/44/8), mean weight 107.6±19.7 kg, <6.5 h sleep/night.
  
  
  METHODS
  Non-pharmacological sleep extension.
  
  
  METHODS
  Sleep duration (diaries and actigraphy watch), sleep quality (Pittsburgh Sleep Quality Index), daily sleepiness (Epworth Sleepiness Scale), fasting glucose, insulin and lipids.
  
  
  RESULTS
  Prior to any intervention, marked improvements occurred between screening and randomization. Sleep duration increased (diaries: 357.4 ±51.2 vs. 388.1±48.6 min/night; mean±SD; P<0.001 screening vs. randomization; actigraphy: 344.3 ±41.9 vs. 358.6±48.2 min/night; P<0.001) sleep quality improved (9.1±3.2 vs. 8.2±3.0 PSQI score; P<0.001), sleepiness tended to improve (8.9±4.6 vs. 8.3±4.5 ESS score; P = 0.06), insulin resistance decreased (0.327±0.038 vs. 0.351±0.045; Quicki index; P<0.001), and lipids improved, except for HDL-C. Abnormal fasting glucose (25% vs. 11%; P = 0.007), and metabolic syndrome (42% vs. 29%; P = 0.007) both decreased. In absence of intervention, the earlier metabolic improvements disappeared at the run-in visit.
  
  
  CONCLUSIONS
  Relatively small sample size.
  
  
  CONCLUSIONS
  Improvements in biochemical and behavioral parameters between screening and randomization changed the "true" study baseline, thereby potentially affecting outcome. While regression to the mean and placebo effect were considered, these findings are most consistent with the "Hawthorne effect", according to which behavior measured in the setting of an experimental study changes in response to the attention received from study investigators. This is the first time that biochemical changes were documented with respect to the Hawthorne effect. The findings have implications for the design and conduct of clinical research.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT00261898.
authors.affiliation: Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cizza
authors.affiliation: Obesity Research Center, Endocrinology Unit, University Hospital of Pisa, Pisa, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Piaggi
authors.affiliation: Section on Pediatric Diabetes and Metabolism, Diabetes, Endocrinology, and Obesity Branch/National Institute of Diabetes & Digestive & Kidney Diseases, Bethesda, Maryland, United States of America.
authors.forename: Kristina I
authors.initials: KI
authors.lastname: Rother
authors.affiliation: Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Csako
mesh_terms: D056044:Actigraphy; D000293:Adolescent; D000328:Adult; D015987:Effect Modifier, Epidemiologic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000503:physiopathology; D012107:Research Design; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D055815:Young Adult