When is ADHD not ADHD (or not as ADHD as it seems)? Perhaps when it is OSA: Obstructive Sleep Apnea. A quick internet search seems to confirm what I heard left and right; sleep apnea symptoms can be mistaken for ADHD symptoms.
A sleep polysomnography was part of my own ADHD diagnosis. Although only one of my sleep cycles was perfect that night, we were able to determine that OSA didn’t explain the symptoms. My ADHD psy-coach tells me that sleep deprivation is the kryptonite for those of us with ADHD.
Here are a few places that treat sleep disorders in Paris. The Hôpital Pitié Salpêtrière Charles Foix is a public institution, therefore probably the least expensive and most institution. There may be a long wait here. Saint-Joseph also does sleep studies. There is also the option of individual doctors who specialize in sleep as seen in this list for example. There is also Hôpital Antoine Béclère and even Hôtel Dieu. I think the Hôtel Dieu may be closed and the website be fantom, needs checking, please leave a comment if you find out.