Sleep has been my biggest issue for the last 10 years and I don't know what to do about it. Even after this time, I still have not much of an idea regarding the cause. I'm in my thirties.

Falling asleep or staying asleep is not an issue, with rare exceptions. However, how I wake up is a whole other story. I hardly remember the last time I woke up truly relaxed, that happens maybe 10 times a year. It's a huge spectrum, most of the time it is somewhere between okay-ish (feeling exhausted after waking up, but it gets much better within 1-2 hours) and super exhausted (like the biggest hangover in my younger years. Can't concentrate at all, minimal effort activities like going up a small staircase become demanding, strained cardiovascular system in general, not hungry.. in short, a lost day). How I wake up is not predictable, there is no obvious pattern or causality.

I am closer to being underweight than overweight. Even on a mediocre day, I can be cheerful. Doctors therefore do not necessarily take me seriously and things happen slowly. Personal "experiments" with an oxygen and pulse tracker clearly show ups and downs when sleeping, but not to a degree to alert doctors with. Over the course of the last 10 years, I actually did 5-6 polysomnograms at a diagnostic center, but every time it was difficult for me to get any sleep there, so the results are close to being worthless. For the 45-60 minutes of sleep that I got per night, the graphs actually did show small irregularities. Which was enough to end up with a CPAP device that I rarely use because I don't feel any better with it.

Although I'm quite sure poor sleep is the immediate reason for my exhaustion, I do not rule out that the root cause is not somatic. There is this other problem of mine, a skin disease which makes me very susceptible to sunlight, which has a severe impact on the way I life and do things. I mainly stay indoors. Doing sports, running errands etc. usually happen after sunset. Bad weather is my friend. I really like my job and colleagues and get well along with everyone, but my personal social circle is small and most of the (spare-)time, I'm alone. Although I don't feel depressed and can be cheerful on most of the days, I talked to someone in therapy for a few months, but it didn't help much. As a software engineer, rational und deterministic thinking makes me wanna try antidepressants, just for the sake of trial and error. But it didn't come to that.

By the way, the last time I went to polysomnograpy, they also did two other tests regarding daytime fatigue. I failed miserably on the first test (basically my ability to keep my pupils focused on something), but succeded in the 99.5 percentile on the second test (reaction time), which is unusual. They came to the conclusion that I have become so accustomed to the situation that my body compensates very well for it. Which coincides with my impressions and helps me in my job and daily life. But doesn't help much when it comes to overall quality of life, or... potential conseqential damages to my cardiovascular system. Over the years, I got used to this whole situation, even with all the time I lost feeling miserable. Sometimes, I'm trying to ignore it and get on with my life, there are some good days after all. But lately, there is this emerging fear of said potential damages. Being in my 30s or 40s and tied to a bed for the rest of my life due to a stroke or something similar is a thought that makes me shudder. Much more than not surviving it.

Maybe it's just plain old sleep apnea with a wrongly adjusted or otherwise not helpful CPAP device (I was at the diagnostic center for trying an ajdustment, but guess what... I just can't sleep at that place). Or maybe the root cause purely psychogenic. Or it's something in between. Which is my current guess, but would be even worse, since it requires some interdisciplinary work and thinking from doctors, which, from my experience, they don't do that much.

I have no clue what to do.