title: Wake detection capacity of actigraphy during sleep.
abstract: OBJECTIVE
  To evaluate the ability of actigraphy compared to polysomnography (PSG) to detect wakefulness in subjects submitted to 3 sleep conditions with different amounts of wakefulness: a nocturnal sleep episode and 2 daytime recovery sleep episodes, one with placebo and one with caffeine. A second objective was to compare the ability of 4 different scoring algorithms (2 threshold algorithms and 2 regression analysis algorithms) to detect wake in the 3 sleep conditions.
  
  
  METHODS
  Three nights of simultaneous actigraphy (Actiwatch-L, Mini-Mitter/Respironics) and PSG recordings in a within-subject design.
  
  
  METHODS
  Chronobiology laboratory.
  
  
  METHODS
  Fifteen healthy subjects aged between 20 and 60 years (7M, 8F).
  
  
  METHODS
  200 mg of caffeine and daytime recovery sleep.
  
  
  RESULTS
  An epoch-by-epoch comparison between actigraphy and PSG showed a significant decrease in actigraphy accuracy with increased wakefulness in sleep conditions due to the low sleep specificity of actigraphy (generally <50%). Actigraphy overestimated total sleep time and sleep efficiency more strongly in conditions involving more wakefulness. Compared to the 2 regression algorithms, the 2 threshold algorithms were less able to detect wake when the sleep episode involved more wakefulness, and they tended to alternate more between wake and sleep in the scoring of long periods of wakefulness resulting in an overestimation of the number of awakenings.
  
  
  CONCLUSIONS
  The very low ability of actigraphy to detect wakefulness casts doubt on its validity to measure sleep quality in clinical populations with fragmented sleep or in situations where the sleep-wake cycle is challenged, such as jet lag and shift work.
authors.affiliation: Centre d'étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Coeur de Montréal, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Paquet
authors.forename: Anna
authors.initials: A
authors.lastname: Kawinska
authors.forename: Julie
authors.initials: J
authors.lastname: Carrier
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002940:Circadian Rhythm / Q000502:physiology*; D004594:Electrophysiology / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography / Q000295:instrumentation; D011237:Predictive Value of Tests; D012890:Sleep / Q000502:physiology*; D020178:Sleep Disorders, Circadian Rhythm / Q000175:diagnosis; D014851:Wakefulness / Q000502:physiology*; D014953:Wrist / Q000502:physiology*