Advanced Sleep Phase Syndrome (ASPS)
- 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.