III. Definitions

  1. Actigraphy
    1. Accelerometer monitors patients overnight movement
    2. Calculates actual patient sleep time
    3. Calculates limb movements over time

IV. 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

V. 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

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