Hello, Just Came Back From My Doctors Apt And A

Hello, just came back from my doctors apt and a referral is being send for a sleep study, she said my oxygen level was down a little and then I told her that in the past 3 or 4 weeks I have noticed that when I turn over on my left side to go to sleep and right before the deep sleep I will wake up dizzy which will then lead to nausea, I just take some deep breaths to calm it, but if I fall asleep on my right side I never have that happen. Then if I turn over to my left it does not do it again, only the first initial time, so I make sure I don't fall asleep on my left. but is a sleep study sounding like it is needed ?