You could also buy one of those two-piece door sensors that sound an alarm when you separate them. Tie one to your hand (or glue it onto a special sleeping glov

You could also buy one of those two-piece door sensors that sound an alarm when you separate them. Tie one to your hand (or glue it onto a special sleeping glove), and hold the other piece. Only potential problem is that you might get a heart attack considering how loud those things can be.