I am a Senior citizen. I take no medicines except for an occasional headache. It seems the product I bought not only in Wisconsin but the product I purchase at Sam's club have the same affect on me. This condition only happens when I take Tylenol PM or regular Tylenor before I go to bed. After I fall asleep I am awakened by my jaw hinges that suddenly relax and literally cause my jaw to fall open. I do not have any jaw grinding in my history. When I do not take them, I do not have the problem. I feel the product is causing a autonomic nerve response that affects only my jaw.