Sudden onset of sleep is reported by 1-31% of PD patients and most patients are not able to completely recall the event., Some PD patients also exhibit significant features of narcolepsy, including cataplexy and sleep-onset rapid eye movement (REM) periods (SOREMPs
) in the multiple sleep latency test (MSLT). Sudden onset of sleep contributes significantly to disease burden and negatively impacts quality of life, impairs daytime functioning, and is associated with motor vehicle crashes. However, many PD patients may not be aware of their sleepiness.
Formal sleep studies, such as the MSLT, can be used to document sleepiness and SOREMPs and to support a diagnosis of narcolepsy.
This is followed by an MSLT the next day to assess the time to sleep onset and to verify the presence of sleep onset rapid eye movement periods (SOREMPs).
Laboratory studies have also found that hypnagogic imagery and sleep paralysis can occur during sleep-onset REM periods (SOREMPs
) and that isolated sleep paralysis is characterised by abundant alpha activity (Takeuchi, Miyasita, Inugami, Sasaki, & Fukuda, 1994; Takeuchi, Miyasita, Sasaki, Inugami, & Fukuda, 1992).
In addition to determining the latency of sleep, the MSLT records the presence of sleep-onset REM periods (SOREMPs