I was recently diagnosed with narcolepsy. My MSLT was abnormal and I have all the symptoms except cataplexy. However my sleep study and MSLT both showed 0% REM sleep. Is this normal?
Doctors Answers (3)
There are clinical criteria for narcolepsy (signs and symptoms) that may include execessive daytime sleepiness, sleep paralysis, hypnagogig hallucinations and some others. Cataplexy may or may not be present as well. Other tests may be helpful to support your diagnosis. Overnight sleep study is performed to exclude sleep apnea and other conditions that may result in daytime sleepiness. MSLT may show signs of excessive daytime sleepiness but also need to show sleep onset REM periods to support the diagnosis of narcolepsy. Having no REM sleep on both studies is unusual and certainly does not support narcolepsy. On the other hand these results do not rule out narcolepsy either as other criteria may be sufficient to make the diagnosis. I think you need to address your concerns with your sleep doc.
You likely do not have Narcolepsy.
The essential ingredient for the diagnosis of narcolepsy is excessive daytime sleepiness. Cataplexy may or may not be present. Often, cataplexy is not initially recognized as it can be very subtle in its presentation; even brief double vision or dropping a pen from your hand. Other symptoms often present with narcolepsy include sleep paralysis (awakening while in REM sleep), "hallucinations" (dreams) as you fall asleep or awaken from sleep, complex behaviors such as finding yourself in someplace but without exact recall how you got there and an assortment of other symptoms which are common but not cardinal symptoms. These would include periodic limb movements of sleep, depression and fragmented sleep architecture with frequent arousals. On some nights, this fragmented sleep may suppress REM and other stages of sleep. On other nights, there may be several REM cycles. The absence of REM sleep during an MSLT is not uncommon. While the presence of 2 sleep onset REM cycles during the MSLT is most often present in narcolepsy, this is not an absolute requirement for making the diagnosis. This can be influenced by REM suppressing medications and the artificial setting. So, your sleep study and MSLT findings are not abnormal but are uncommon.