title: Evaluation of immobility time for sleep latency in actigraphy.
abstract: BACKGROUND
  Actigraphy has become an important tool in sleep research, however, most actigraphic models have had little evaluation of their sleep scoring software. Some reports have described poor agreement of actigraph and polysomnogram (PSG) results. In this study, we examined the accuracy of the Actiwatch-L instrument with Actiware((R)) software version 5.0 (Minimitter-Respironics, Bend, Oregon).
  
  
  METHODS
  We analyzed the sleep latencies and total sleep times in 33 actigraph recordings and compared performance to simultaneous polysomnography. For scoring sleep latency, the default criterion for scoring sleep onset (10min of immobility) was compared with criteria of 4, 5, 6, and 15min of immobility, and low, middle, and high activity thresholds were compared.
  
  
  RESULTS
  Of 4, 5, 6, 10 and 15min of actigraphic immobility, the 5min criterion yielded the most accurate sleep latencies. The 5min criterion also yielded near-optimal estimates for total sleep time and wake after sleep onset.
  
  
  CONCLUSIONS
  We found that a default 10-min immobility parameter for sleep onset was not as accurate as 5min for scoring sleep latency and total sleep time in this clinical sample. There is a need for expanded samples to further evaluate algorithm scoring parameters and the search for superior alternatives.
authors.affiliation: Scripps Clinic Sleep Center, W207, 10666 N Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Kyu Young
authors.initials: KY
authors.lastname: Chae
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Kripke
authors.forename: J Steven
authors.initials: JS
authors.lastname: Poceta
authors.forename: Farhad
authors.initials: F
authors.lastname: Shadan
authors.forename: Shazia M
authors.initials: SM
authors.lastname: Jamil
authors.forename: John W
authors.initials: JW
authors.lastname: Cronin
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Kline
mesh_terms: D000465:Algorithms; D005121:Extremities / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D009068:Movement; D017286:Polysomnography; D011930:Reaction Time; D012890:Sleep; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012984:Software / Q000592:standards*; D013997:Time Factors