Falling asleep at the "drop of a hat" very well CAN be life-threatening. Does she fall asleep at the wheel?
Some basic sleep hygiene may also help. Sit up straight on the sofa. Sofa for sitting, not sleeping. Bed for sleeping. Same bedtime each night. Same wake-up time each day, even on holidays and weekends. There's more. I have been through sleep hygiene "therapy" at the recommendation of my doctor. It HELPS!!
