No one warned me about the paste in my hair. They used some sort of paste to hold the sensors on my head. So, don't wash your hair before the sleep study because you will absolutely need to wash your hair right after. Honestly, it was the worst night's sleep ever. I was cold and so uncomfortable, and woke up more times than I usually do. Definitely pee right before the tech hooks up the wires because it is a pain to do it when you really have to go. And be patient- My tech took a while to respond to my alert. Good luck!