Assertion: narcolepsy's cause | /r/HasProperty | unclear
Facets:
value: often
type: DEGREE
Source sentences:
text: But this does not explain all cases of narcolepsy, and the exact cause of the problem is often unclear.
text: In most cases of narcolepsy without cataplexy (and in rare cases with cataplexy), the cause of the symptoms is unclear and the diagnostic is purely based on the result of an abnormal sleep test called the multiple sleep latency test (MSLT).
text: The precise cause of these hallucinations is unclear.