My Sister Is On This Drug. She Has Been Taking

My sister is on this drug. She has been taking it for 2 or 3 yrs. Recently, for about 6 months, she has been suddenly waking from a sleep that occurred while sitting on side of bed or as recently, sitting on the commode. Would this drug cause her to suddenly go to sleep? She has had no problems while being active. Only when sitting. This sleep can last for 2 or 3 hours.
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