So... this is something I deal with. There are a lot of potential causes - as I learned when I first went to the doctor about it. For me, that resulted in a lot of tests - for lyme disease, sleep apnea, diabetes, some kidney diseases, some liver diseases, and plenty more that I'm forgetting.
When nothing else came back as positive, I got a diagnosis of "chronic fatigue syndrome". Doctors don't know what causes it, and they don't know how to cure it. 🙄
My advice (if you'd like it) is to go talk to your doctor. Make sure he/she actually listens to you -- don't allow them to blow you off with things like, "it's probably just adjusting to the baby" or other nonsense. (I recall reading studies in the past that doctors are way more likely to discount "nebulous" symptoms when they're presented by a woman than by a male.) Ideally of course, your doctor takes it seriously right from the start. He/she should order blood and urine tests, because that allows for a lot of very easy tests for a lot of potential causes. He/she may also order a sleep study for you. For example, if you didn't lose all the weight from pregnancy, it could be contributing to sleep apnea.
If you'd like to talk about it or ask questions, just reply and I'll get the notification. If you'd like to chat in private instead, by all means drop me a PM; I'd be happy to answer questions.
Good luck! Not getting restful sleep sucks! The good news is that there's almost always an underlying cause, and it's just up to your doctor to find it so it can be treated.
