Yes I had difficulty sleeping for the study. It took 3 of them to finally get me all set up. Of course that was a long time ago. Don't let them try to talk u out of taking yr regular meds including sleeping meds if u take them. It's part of your normal routine n that is what they need to test. Also if you are absolutely unable to sleep on yr back insist that they don't try to make you. That is why I never slept on my 1st study.