woman narcolepsy

“What sort of laboratory tests can help identify narcolepsy?”

Polysomnography (PSG): An objective measurement of nighttime physiology.1

PSG testing is routinely indicated, together with a multiple sleep latency test (MSLT), for assessing the potential presence of narcolepsy.1

  • PSG testing helps identify whether other sleep pathologies, such as obstructive sleep apnea, are present.2
  • PSG testing...
    • Records normal and abnormal physiologic activity over the course of a night.1,2
    • Documents the adequacy of sleep, including frequency, duration, and total amounts of different sleep stages.1,2
  • In addition, PSG testing results can identify the nighttime occurrence of sleep onset rapid eye movement periods (SOREMPs).1
    • A SOREMP is defined as REM sleep within 15 minutes of sleep onset.3
    • A SOREMP on an overnight PSG can be used as 1 of the 2 or more SOREMPs necessary for a narcolepsy diagnosis according to the ICSD-3* criteria.3
  • A SOREMP on a nocturnal PSG is a highly specific marker for narcolepsy in the absence of another sleep disorder, but with low sensitivity.3,4
    • In patients who experience a SOREMP on a nocturnal PSG...4
      • Reevaluation of cataplexy should be considered.4
      • Combination PSG/MSLT should be considered.4
  • PSG testing also measures airflow, respiratory effort, and leg activity.1,2

Interpreting PSG testing results.

Normal Sleep4,5
  • Sleep stages cycle in periods alternating throughout the night in intervals of approximately 90 to 110 min.
  • SOREMPs are usually absent.
Sleep Suggestive of Narcolepsy3,4,6
  • Amount of Stage 1 sleep is increased.
  • One or more SOREMPs are usually present.

*ICSD-3 = International Classification of Sleep Disorders, 3rd ed.