u/OnePsychological5991

I’m a healthy, active 22-year-old trying to figure out what’s changed.
I started CPAP (nasal mask, fixed pressure of 5 cm H₂O) in April 2025. For the first 7 months it completely changed my life. I woke up rested, had vivid dreams almost every night, and got morning wood basically every day. Libido was great.
Then I moved to Utah (~7,000 ft elevation). Within a couple of weeks, everything changed. Morning wood almost disappeared (maybe 10–12 times over six months), dreams became much less vivid, and I felt noticeably more tired. My doctor never changed my pressure.

Last summer when CPAP was working well I weighed around 169–175 lbs. In Utah I was 180–188 lbs. A few months ago I moved back to my hometown in the Midwest at a much lower elevation. I’m now back down to 176 lbs, on the exact same CPAP settings and mask, and at a weight close to where I started—but I’m still having the same issues. I actually felt better for the first few days after moving back, then everything slowly went back downhill.

My blood work is normal:
Total testosterone: 721 ng/dL
Free testosterone: 122 pg/mL
LH, FSH, prolactin, estradiol, thyroid, glucose, etc. all normal.

A couple of other things I’ve noticed:
I recently caught myself snoring while wearing CPAP.
I can breathe through my mouth with my nasal mask much more easily than I could when I first started.
The CPAP supply store gave me a chin strap because they suspected mouth leaking.
The biggest mystery is that I went from morning wood almost every day to maybe once every 10 days, and that change happened alongside feeling less rested and having much less vivid dreams.
Has anyone experienced something similar where CPAP initially worked great but gradually stopped feeling effective even though the machine reported good numbers? Did it end up being pressure, mouth leaks, altitude, sleeping position, needing another sleep study, or something else?
I’d really appreciate hearing from anyone who’s gone through something similar.

I’m a 22-year-old male, healthy, lean, active, and I’m trying to figure out what’s changed.
I started CPAP (nasal mask) in April 2025 at a fixed pressure of 5 cm H₂O. For the first 7 months, it was honestly life-changing. I woke up feeling rested every day, had vivid dreams almost every night, and woke up with morning wood basically every morning. Libido was great.

Then I moved to Utah (around 7,000 ft elevation). Within a couple of weeks, everything changed. Morning wood almost completely disappeared (maybe 10–12 times over six months), dreams became much less vivid, and I felt noticeably more tired. I also gained 10-15 lbs so that also had something to do with it I’m sure. I asked my sleep doctor about increasing my pressure, but my settings stayed the same.
Three months ago I moved back to my home in the Midwest( Normal elevation) .

For the first few days I actually felt better and got morning wood again, but then the symptoms slowly came back. Now I’m almost back to how I felt in Utah.
Here’s what’s confusing me:
Same CPAP settings (5 cm H₂O)
Same nasal mask
Dropped to around the weight I was last summer (currently ~176 lb)
Blood work looks normal:

Total testosterone: 721 ng/dL
Free testosterone: 122 pg/mL
LH, FSH, prolactin, estradiol, thyroid, glucose, etc. all normal.
CPAP reports “good” scores.
A couple of things I’ve noticed:
I recently caught myself snoring while wearing the CPAP.
I can now breathe through my mouth with the nasal mask much more easily than I could when I first got it.
The supply store gave me a chin strap to try because they thought mouth leaking could be an issue.
The biggest thing bothering me isn’t even libido—it’s that I went from waking up with morning wood almost every day to maybe once every 10 days. Since this all happened, I also don’t feel as rested and my dreams aren’t nearly as vivid. Those changes all seemed to happen together.
Has anyone had something similar happen where CPAP initially worked great but gradually seemed less effective even though the machine looked “fine”? Did it end up being pressure, mouth leaks, sleeping position, needing another sleep study, or something else?
I’d really appreciate hearing from anyone who’s gone through something similar.