Medical Terminology

type 1 narcolepsy (T1N)

The International Classification of Sleep Disorders, third edition, divides narcolepsy into type 1 and type 2 (the previous edition used the terms narcolepsy with and without cataplexy). The new criteria for T1N require a combination of hypersomnolence and either low hypocretin levels in the cerebrospinal fluid or cataplexy plus short average sleep latency (≤ 8 minutes) and 2 or more sleep-onset REM periods (SOREMPs) on the Multiple Sleep Latency Test (MSLT). A SOREMP (within 15 minutes) of sleep onset on polysomnography (or PSG, a sleep study) may replace one of the SOREMPs on the MSLT. Read more About Related Sleep Disorders.