Hi Symphony,
I often had really bad night sweats during the first 4-5 (?) years that I was sick. I first got sick in 1990, at age 29, and lay people (not doctors, thankfully) would often suggest menopause when I mentioned this symptom. But that's because it's the only thing they know about that can cause night sweats. They don't realize how many other things can cause this symptom.
I suppose it is possible that it might be menopause (you could talk with your doctor, look at lists of other menopause symptoms, maybe have your hormones levels tested, etc.) but it's not very likely. As you can see just by the few people responding in this thread, night sweats are a common symptom of ME.
I'm almost 52 and I still have a very regular period. I'm not even in peri-menopause yet. So, it's pretty obvious that my night sweats had nothing to do with menopause. Like Tammy, my night sweats were always worse when I was feeling worse.
After being sick for 23 years I rarely have night sweats now. One factor that seemed to reduce them for me was treating my orthostatic intolerance. My diagnosis is Neurally Mediated Hypotension, which means my biggest problem seems to be dropping blood pressure, and only a bit of increased heart rate, but I might also have some POTS now after so many years.
While I no longer have night sweats all the time, I do get them every once in a while-- maybe 3-4 times a year? I wake up with my hair damp, and my t-shirt drenched, with sweat mostly around my neck and chest area but not under my arms. I have to change both the pillow case and my t-shirt when this happens. And it seems to smell worse than sweat that's caused by heat or exertion (but maybe that's my imagination).
In my case it has nothing to do with the room temperature, or type of sheets, or anything like that. It's somehow related to overexertion from the previous day or two and then the subsequent crash from PEM/PENE. But not all my crashes cause this symptom. I have never figured out exactly what triggers this problem. I'm just happy that it's rare now compared to those first few years when it seemed to happen at least twice a week.
I have no idea whether your night sweats are anything like mine at all. But I'm sharing my experience just in case it might help you. Good luck in figuring out what is causing your night sweats.