title: Power spectral analysis of EEG activity during sleep in cigarette smokers.
abstract: BACKGROUND
  Research on the effects of cigarette smoking on sleep architecture is limited. The objective of this investigation was to examine differences in sleep EEG between smokers and nonsmokers.
  
  
  METHODS
  Smokers and nonsmokers who were free of all medical comorbidities were matched on different factors, including age, gender, race, body mass index, and anthropometric measures. Home polysomnography was conducted using a standard recording montage. Sleep architecture was assessed using visual sleep-stage scoring. The discrete fast Fourier transform was used to calculate the EEG power spectrum for the entire night within contiguous 30-s epochs of sleep for the following frequency bandwidths: delta (0.8 to 4.0 Hz); theta (4.1 to 8.0 Hz); alpha (8.1 to 13.0 Hz); and beta (13.1 to 20.0 Hz).
  
  
  RESULTS
  Conventional sleep stages were similar between the two groups. However, spectral analysis of the sleep EEG showed that, compared to nonsmokers, smokers had a lower percentage of EEG power in the delta-bandwidth (59.7% vs 62.6%, respectively; p < 0.04) and higher percentage of EEG power in alpha-bandwidth (15.6% vs 12.5%, respectively; p < 0.001). Differences in the EEG power spectrum between smokers and nonsmokers were greatest in the early part of the sleep period and decreased toward the end. Subjective complaints of lack of restful sleep were also more prevalent in smokers than in nonsmokers (22.5% vs 5.0%, respectively; p < 0.02) and were explained, in part, by the differences in EEG spectral power.
  
  
  CONCLUSIONS
  Cigarette smokers manifest disturbances in the sleep EEG that are not evident in conventional measures of sleep architecture. Nicotine in cigarette smoke and withdrawal from it during sleep may contribute to these changes and the subjective experience of nonrestorative sleep.
authors.affiliation: Department of Epidemiology, Johns Hopkins University Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 2122, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Jonathan
authors.initials: J
authors.lastname: Samet
authors.forename: Brian
authors.initials: B
authors.lastname: Caffo
authors.forename: Isaac
authors.initials: I
authors.lastname: Bankman
authors.forename: Naresh M
authors.initials: NM
authors.lastname: Punjabi
mesh_terms: D004569:Electroencephalography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*; D012907:Smoking / Q000503:physiopathology*; D017550:Spectroscopy, Fourier Transform Infrared