title: Sleep-wake evaluation from whole-night non-contact audio recordings of breathing sounds.
abstract: OBJECTIVE
  To develop and validate a novel non-contact system for whole-night sleep evaluation using breathing sounds analysis (BSA).
  
  
  METHODS
  Whole-night breathing sounds (using ambient microphone) and polysomnography (PSG) were simultaneously collected at a sleep laboratory (mean recording time 7.1 hours). A set of acoustic features quantifying breathing pattern were developed to distinguish between sleep and wake epochs (30 sec segments). Epochs (n = 59,108 design study and n = 68,560 validation study) were classified using AdaBoost classifier and validated epoch-by-epoch for sensitivity, specificity, positive and negative predictive values, accuracy, and Cohen's kappa. Sleep quality parameters were calculated based on the sleep/wake classifications and compared with PSG for validity.
  
  
  METHODS
  University affiliated sleep-wake disorder center and biomedical signal processing laboratory.
  
  
  METHODS
  One hundred and fifty patients (age 54.0±14.8 years, BMI 31.6±5.5 kg/m2, m/f 97/53) referred for PSG were prospectively and consecutively recruited. The system was trained (design study) on 80 subjects; validation study was blindly performed on the additional 70 subjects.
  
  
  RESULTS
  Epoch-by-epoch accuracy rate for the validation study was 83.3% with sensitivity of 92.2% (sleep as sleep), specificity of 56.6% (awake as awake), and Cohen's kappa of 0.508. Comparing sleep quality parameters of BSA and PSG demonstrate average error of sleep latency, total sleep time, wake after sleep onset, and sleep efficiency of 16.6 min, 35.8 min, and 29.6 min, and 8%, respectively.
  
  
  CONCLUSIONS
  This study provides evidence that sleep-wake activity and sleep quality parameters can be reliably estimated solely using breathing sound analysis. This study highlights the potential of this innovative approach to measure sleep in research and clinical circumstances.
authors.affiliation: Department of Biomedical Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Eliran
authors.initials: E
authors.lastname: Dafna
authors.affiliation: Sleep-Wake Disorders Unit, Soroka University Medical Center, and Department of Physiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Israel.
authors.forename: Ariel
authors.initials: A
authors.lastname: Tarasiuk
authors.affiliation: Department of Biomedical Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Zigel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012135:Respiratory Sounds / Q000502:physiology*; D012890:Sleep; D013637:Tape Recording; D014851:Wakefulness; D055815:Young Adult