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Advanced Sleep Phase Syndrome (ASPS)

  • “Larks”
  • Major sleep episode is advanced in relation to the desired clock time, resulting in early evening sleepiness, early sleep onset, and awakening earlier than desired.
  • Intervening sleep pattern is normal and undisturbed.
  • More common in the elderly.
  • No biochemical or anatomic abnormalities.
  • PSG:  Need 2 nights with an intervening MSLT.
  • PSG #1:  Over the patient’s usual sleep time.  Start MSLT 2 hours after awakening.  PSG #2:  Over the patient’s desired sleep time. 
  • Differential diagnosis:  Depression has early AM awakenings, but PSG shows decreased REM latency and decreased SWS.