hello my dentist recently gave me teeth whitening strips and I usually wear a top retainer and a bottom night gaurd while I sleep, but my dentist gave me retainer like things to wear when I sleep, but my retainer and night gaurd both come out sometimes during my sleep and I'm afraid to sleep on the teeth whitening retainer like things with bleach on them. I don't want them to fall out because they are kind of loose.. what should I do?