My Boyfriend Recently Broke His Hip And Part Of His

My boyfriend recently broke his hip and part of his treatment is lidocaine patch 5% for pain. His visiting nurse is making him take it off and discard it in front of her only after 7 hrs of use. He says he can do that on his own when 8 pm comes around. If he forgets and falls asleep is that dangerous to leave it on all night, or even a few hrs after the 12 hrs recommended on the package. I do live with him so I can remind him but I just wanted to know. You know how life gets and you get busy and forget. Thanks, Donna