title: Sleep/wake measurement using a non-contact biomotion sensor.
abstract: We studied a novel non-contact biomotion sensor, which has been developed for identifying sleep/wake patterns in adult humans. The biomotion sensor uses ultra low-power reflected radiofrequency waves to determine the movement of a subject during sleep. An automated classification algorithm has been developed to recognize sleep/wake states on a 30-s epoch basis based on the measured movement signal. The sensor and software were evaluated against gold-standard polysomnography on a database of 113 subjects [94 male, 19 female, age 53±13years, apnoea-hypopnea index (AHI) 22±24] being assessed for sleep-disordered breathing at a hospital-based sleep laboratory. The overall per-subject accuracy was 78%, with a Cohen's kappa of 0.38. Lower accuracy was seen in a high AHI group (AHI >15, 63 subjects) than in a low AHI group (74.8% versus 81.3%); however, most of the change in accuracy can be explained by the lower sleep efficiency of the high AHI group. Averaged across subjects, the overall sleep sensitivity was 87.3% and the wake sensitivity was 50.1%. The automated algorithm slightly overestimated sleep efficiency (bias of +4.8%) and total sleep time (TST; bias of +19min on an average TST of 288min). We conclude that the non-contact biomotion sensor can provide a valid means of measuring sleep-wake patterns in this patient population, and also allows direct visualization of respiratory movement signals.
authors: BiancaMed, NovaUCD, Belfield, Dublin 4, Ireland. philip.dechazal@biancamed.com
authors: Philip
authors: P
authors: De Chazal
authors: Niall
authors: N
authors: Fox
authors: Emer
authors: E
authors: O'Hare
authors: Conor
authors: C
authors: Heneghan
authors: Alberto
authors: A
authors: Zaffaroni
authors: Patricia
authors: P
authors: Boyle
authors: Stephanie
authors: S
authors: Smith
authors: Caroline
authors: C
authors: O'Connell
authors: Walter T
authors: WT
authors: McNicholas
mesh_terms: D056044:Actigraphy / Q000295:instrumentation*; D000328:Adult; D000465:Algorithms; D003936:Diagnosis, Computer-Assisted / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D017286:Polysomnography / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*; D012984:Software; D014851:Wakefulness