Actigraphy, Actigraph Watch, Sleep Efficiency, Sleep Latency, Sleep Onset Latency

  • Definitions
  1. Actigraphy
    1. Accelerometer monitors patients overnight movement
    2. Calculates actual patient sleep time
    3. Calculates limb movements over time
  • Technique
  1. Patient wears a sensor on their wrist or ankle overnight for days to weeks
  2. Device measures frequency and degree of limb movements over time
  • Interpretation
  1. Sleep Phases
  2. Sleep Duration
  3. Sleep Patterns
  4. Sleep Latency (Sleep Onset Latency)
    1. Time for a person to fall asleep after intending to sleep (e.g. lying down, lights off)
    2. Normally 10-20 minutes
  5. Sleep Efficiency
    1. Key metric in Cognitive Behavioral Therapy for Insomnia
    2. Normally >80%
    3. Sleep Efficiency = (100 * TST / TIB)
      1. Where TST is total sleep time
      2. Where TIB is time in bed