Ugh. Sometimes I think drs just say "it's all in your head" as an easy way to handwave people out the door. They get paid regardless if they solve your problem or not. I'm sorry that happened to you. If you aren't sleeping well that's an issue. Any sleep specialist worth their salt knows this.

It took me about 10 years to get my diagnosis so I feel this. If you have the means maybe seek out a different sleep specialist and do a second test under that one. It's frustrating that to need to do that, but unfortunately that's what it comes to when you run into asshole doctors who don't care, don't bother listen, or just assume your a moron and your suffering is your own doing.

Best luck to you! I hope you get it figured out and find some relief soon