Hi
newtoCPAP2018,
Let me start by saying I do understand. There was a time in my 20s when I suffered from panic in certain contexts. And I learned to get over it. It doesn't happen to me now.

It's been a long time since it has.
knothead has suggested gradual adjustment.
kteague has suggested a similar process of acclimatization.
Janknitz has laid out a very thoughtful process of systematic desensitization. And those methods do work. So kudos to them.
But you have said, in effect, you haven't got time to go thru any of those processes. You need something quicker. And now.
The modern view from neuroscience is that anxiety and panic are learned responses - and it is possible to unlearn them. And research in the last few years suggests that it's possible to unlearn the panic response quite quickly - via a method which uses what we now know about how panic 'operates' in the brain, specifically in a bit called the amygdala.
And by 'quite quickly' I mean in less than half an hour.
I'm not going to try and describe the process. I am going to point you to a 12-minute video on YouTube. The method was developed by Dr Ronald Ruden, an American medical doctor and neuroscientist, and the person on this video studied directly with Dr Ruden, and made this video with his approval.
https://www.youtube.com/watch?v=0C1liEFCZm4
I think the ideal solution would be for you to find a Havening practitioner near you - or within a distance you feel you can reasonably travel. It is better to have someone experienced in this technique to guide you thru the process. But if that's not possible, then watch the tape twice. First, to get the overall idea of the process. And then a second time, to do the process.
And you might, for your first piece of change,
pick some issue other than the big problem facing you 
- a smaller something - a minor something-that-bothers-me. That way you can test-drive the process and get it right, without getting too caught up in any emotion.
And again, the reason I'm suggesting this new method – apart from it being very effective when it's done right – is: I get that you need something now which gets you through the sleep study. I hope that, for you, this is it.
