title: Short- and Long-Term Sleep Stability in Insomniacs and Healthy Controls.
abstract: OBJECTIVE
  Assess the short- and long-term stability of sleep duration in patients with insomnia and normal-sleeping controls.
  
  
  METHODS
  Observational short-term and prospective studies.
  
  
  METHODS
  Sleep laboratory.
  
  
  METHODS
  Patients with insomnia (n = 150) and controls (n = 151) were recruited from the local community or sleep disorders clinic. A subsample of 95 men from the Penn State Adult Cohort (PSAC) were followed up 2.6 y after their initial visit.
  
  
  METHODS
  Participants underwent a physical examination and 8-h polysomnography (PSG) recording for 3 consecutive nights (controls and insomniacs), or 2 single nights separated by several years (PSAC). Intraclass correlation coefficients (ICCs) assessed the stability of the variables total sleep time (TST), sleep onset latency (SOL), and wake after sleep onset (WASO). We also examined persistence of the first-night classification of "short" versus "normal" sleep duration on subsequent nights.
  
  
  RESULTS
  Stability of TST, SOL, and WASO based on 1 night were slight to moderate in both patients with insomnia (ICC = 0.37-0.57) and controls (ICC = 0.39-0.59), and became substantial to almost perfect when based on the average of 3 nights (ICC = 0.64-0.81). We observed similar degrees of stability for TST and WASO in the longitudinal sample, with moderate stability based on a single night and substantial stability based on both nights. In examining the persistence of "short" and "normal" sleep duration, 71.4% (controls), 74.7% (patients with insomnia), and 72.6% (longitudinal sample) of participants retained their first-night classifications over subsequent nights.
  
  
  CONCLUSIONS
  Sleep duration variables, particularly total sleep time based on 3 consecutive nights in both patients with insomnia and controls or two single-night recordings separated by several years, are stable and reflect a person's habitual sleep. Furthermore, a single night in the laboratory may be useful for reliably classifying one's sleep duration.
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA.
authors.forename: Jordan
authors.initials: J
authors.lastname: Gaines
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA.
authors.forename: Alexandros N
authors.initials: AN
authors.lastname: Vgontzas
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA.
authors.forename: Julio
authors.initials: J
authors.lastname: Fernandez-Mendoza
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA.|Department of Psychiatry, School of Medicine, University of Crete, Heraklion, Crete, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Basta
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA.
authors.forename: Slobodanka
authors.initials: S
authors.lastname: Pejovic
authors.affiliation: Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, PA.
authors.forename: Fan
authors.initials: F
authors.lastname: He
authors.affiliation: Sleep Research and Treatment Center, Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA.
authors.forename: Edward O
authors.initials: EO
authors.lastname: Bixler
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006184:Habits; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D015203:Reproducibility of Results; D012890:Sleep / Q000502:physiology*; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis / Q000503:physiopathology*; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology
keywords: good sleepers; insomnia; polysomnography; sleep; stability