title: Subjective daytime sleepiness and daytime function in patients on stable methadone maintenance treatment: possible mechanisms.
abstract: BACKGROUND
  Subjects using opioids on a chronic basis have been reported to have a high prevalence of abnormal sleep architecture and central sleep apnea (CSA). The severity of CSA is, in part, related to blood opioid concentration. The aim of this study was to investigate subjective daytime sleepiness and daytime function in patients who are on stable methadone maintenance treatment (MMT) and to assess the possible mechanisms involving abnormal sleep architecture, CSA severity, and blood methadone concentration.
  
  
  METHODS
  Fifty patients on MMT and 20 normal control subjects matched for age and body mass index were tested using polysomnography, blood toxicology, Epworth Sleepiness Scale (ESS), Functional Outcome of Sleep Questionnaire (FOSQ), and Beck Depression Inventory (BDI).
  
  
  RESULTS
  The patients receiving MMT had significantly worse daytime function, were depressed, and had increased daytime sleepiness when compared with the control subjects (FOSQ 15.47 +/- 3.19 vs 19.4 +/- 0.47, BDI 14.64 +/- 10.58 vs 2.05 +/- 2.46, ESS 7.1 +/- 5 vs 2.05 +/- 1.76; all p values < 0.001). Nevertheless, daytime sleepiness in the patients receiving MMT was, on average, within the normal range (ESS < or = 10). Multiple regression analysis demonstrated that the severity of CSA, blood methadone concentration, and abnormalities in sleep architecture were not significant in predicting the variance of ESS or FOSQ (all p values > 0.05) in these patients receiving MMT. The BDI was the best predictive variable for FOSQ, explaining 16% of the variance (p = 0.004).
  
  
  CONCLUSIONS
  Patients on stable MMT have, in general, normal subjective daytime sleepiness but impaired daytime function that partially relates to depression. The changes in sleep architecture, presence of CSA, and blood methadone concentrations do not significantly affect subjective daytime sleepiness and daytime function in these patients.
authors.affiliation: Department of Respiratory & Sleep Disorders Medicine, Western Hospital, Department of Medicine (RMH & WH), The University of Melbourne, Melbourne, Australia. dwang@med.usyd.edu.au
authors.forename: David
authors.initials: D
authors.lastname: Wang
authors.forename: Harry
authors.initials: H
authors.lastname: Teichtahl
authors.forename: Cathy
authors.initials: C
authors.lastname: Goodman
authors.forename: Olaf
authors.initials: O
authors.lastname: Drummer
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Grunstein
authors.forename: Ian
authors.initials: I
authors.lastname: Kronborg
mesh_terms: D000328:Adult; D001315:Australia; D016022:Case-Control Studies; D003863:Depression / Q000139:chemically induced; D005260:Female; D006801:Humans; D008297:Male; D008691:Methadone / Q000009:adverse effects* / Q000627:therapeutic use; D008875:Middle Aged; D009294:Narcotics / Q000009:adverse effects* / Q000627:therapeutic use; D009293:Opioid-Related Disorders / Q000534:rehabilitation; D017286:Polysomnography; D015995:Prevalence; D012044:Regression Analysis; D012720:Severity of Illness Index; D020182:Sleep Apnea, Central / Q000139:chemically induced* / Q000523:psychology; D012894:Sleep Stages / Q000187:drug effects* / Q000502:physiology; D011795:Surveys and Questionnaires
chemical_list: D009294:Narcotics; D008691:Methadone