Yes, get a CPAP. You have to go to a sleep doctor, get tested and then you can get one. I have one and it absolutely changed my life, nearly everyone says that. It effectively fixes obstructive sleep apnea.
Was this a problem for you? I have a feeling a sleep medication would help with this but won't that interfere with the study?
At the end of the day, you will eventually fall asleep and hit deep sleep and they'll get the measurements they need.
No one sleeps well knowing they are being watched and hooked up to all those sensors. :)