title: Non-constraining sleep/wake monitoring system using bed actigraphy.
abstract: This paper introduces a new method, bed actigraphy (BACT) for user-friendly sleep-wake monitoring. BACT provides a non-intrusive acquisition of activity data, and in particular does not require that sensors be attached to the subject's body. The system consists of four load-sensing cells supporting the bed, an A/D converter, and a microcontroller with appropriate software. The performance of BACT was compared to that of standard polysomnography (PSG) recordings and wrist-worn actigraphy (ACT). Ten normal volunteers underwent overnight PSG recordings and were examined simultaneously with BACT and ACT. An automatic scoring algorithm scored each 30-s epoch of the BACT recordings for either 'Wake' or 'Sleep.' A sleep specialist manually scored the PSG recordings, and the results were divided into 'Wake' and 'Sleep' categories. The three methods showed a significant correlation when compared with in the contingency test. The mean epoch-by-epoch agreements between the BACT and PSG, ACT and PSG, and BACT and ACT recordings were 95.2, 92.9, and 94.3%, respectively. The mean absolute differences in sleep percentage (SP) between them were 1.8 +/- 0.82, 3.4 +/- 1.45, and 1.9 +/- 1.16 %, respectively. BACT differentiation of the 'Wake' and 'Sleep' stages proved to be sufficiently robust, and its results were comparable to PSG analysis. This finding supports the experimental and clinical value of bed-activity monitoring during sleep.
authors.affiliation: Interdisciplinary Program in Medical and Biological Engineering, Seoul National University, Graduate School, Seoul, Republic of Korea.
authors.forename: Byoung Hoon
authors.initials: BH
authors.lastname: Choi
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Seo
authors.forename: Jong Min
authors.initials: JM
authors.lastname: Choi
authors.forename: Hong Bum
authors.initials: HB
authors.lastname: Shin
authors.forename: Joo Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Do Un
authors.initials: DU
authors.lastname: Jeong
authors.forename: Kwang Suk
authors.initials: KS
authors.lastname: Park
mesh_terms: D000328:Adult; D006801:Humans; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods*; D009068:Movement; D017286:Polysomnography; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages; D012893:Sleep Wake Disorders / Q000175:diagnosis; D012984:Software; D014851:Wakefulness / Q000502:physiology*