Unless you have any serious symptoms a repeat MRI seems to be of not much value. I have done so many MRIs/MRAs/CT scans and it showed the same thing. I even did a spinal tap and they did all analysis on my spinal fluid including for LYME disease.

I also did sleep study and I would highly recommend it. They do collect lot of data when you sleep including teeth grinding etc., For me it showed only mild snoring and no sleep apnea, restless legs etc., No further action or studies needed in my case. But I know something is not right with my sleep. I sleep good (8-9 hours) without any sleep aid but still I am tired all day and gets better in the night. Weird!