@Griff25,
I just joined today, and low someone else has recently posted about Sleep Apnoea, a problem I have had diagnosed about 5 years ago, and thought was managed, until today. I too suffered from non-specific lethargy for most of my life and was seeing several GPs, including diagnostic specialist GP, without any positive test results, until I was nearly in a vegitative state of constant exhaustion. My first sleep clinic was public, and my first sleep doctor treated me badly, on reflection most medical professionals treat me badly, for reasons which are now obvious. The treatment only provided some improvement, after six months I did not feel like "superman", there was some other problems, which I did not get diagnosed with until last year, which I feel I have to mention later.
Since purchasing my CPAP machine with help from private health fund and an overly helpful parent, I have had a number of problems with the accesories for the CPAP and my own health has required changes to the settings. Most recently, the chin strap I wear under the mask has become loose with wear, and I am unable to adjust it any tighter. I had not thought this to be an overly important issue, but most people with Sleep Apnoea do not know what is going on while they are asleep. It might seem either obvious that you are not conscious while asleep or contradictory that you don't realise your keep waking up. The lack of oxygen affects memory, so you may not remember why you took your mask off 40 minutes after putting it on. If you have less or more apnoeas, you mostly will be unaware of the change, because for most sufferers, the apnoea usually only half-awakens part of the brain.
So back to today, checked my CPAP machine for the results of last night, (it is the type where the user can easily access that information on the control panel), and the numbers were bad, particularly the air leakage, so I got the chin strap fixed, and hopefully tonight will sleep better. But my advice is, even if it doesn't feel like it's working, or if you have been using CPAP for so long, you don't think you need it any more, it is still necessary. If you suspect something is not perfect, get it checked, because you probably don't even know for certain, what is happening while you sleep.
Also I might add, my current bugbear is multiple conditions with similar symptoms. It is a bugbear because current professional medical testing schemes work very hard to try to eliminate similar diagnosis. This prevented me from being treated, because no doctor could find one diagnosis which fit my symptoms. This year I turn 41 years old and have three professionally diagnosed conditions which affect energy levels from birth. In my memory, I started having symptoms of Sleep Apneoa when aged 4, Asperger's from age 4, ADHD from age 5, I probably had symptoms earlier, but have few memories before age 4 as expected. I was diagnosed for Sleep Apnoea at age 35, ADHD at 39 and Asperger's at 40.
If you are a medical professional who knows the history of any of these conditions, you will know that I was too old for early intervention, which is the main focus of treatment for all three. Now it is very difficult for me to receive additional assistance, because there are very few programs I am entitiled to. I need to access most of my treatments through private, although mostly medicare subsidised providers. Because I need more than 10 counselling sessions per year, this financially limits my recovery, so my only long term hope is that I am elligible for NDIS in 2016 to 2019, which is already appearing to be unlikely.
So in your situation, if you are diagnosed positively for Sleep Apnoea, it does not necessarily mean your mental or psychiatric disorder is going away, or that the Apnoea was the cause of all the psych problems. It certainly will help, more in the long term than the short term, but I think it would be rare for even a mild condition to be 'cured' by combination with CPAP or surgery. From my experience, which weighs a lot more than a research paper, Apnoeas not only mimic some issues, but also can make other issues worse, and can hide some issues in another layer of complexity. Although, my Psych issues became more recognisable after long term CPAP, because the improved energy allowed more consistant clarity of thought, allowing me to express what was going on inside my head. You will probably experience some of the same things, and change your outlook on mental health.
I hope my experience is helpful to you in the future.