3rd trimester insomnia and tiredness in the evening

I am 34 weeks pregnant now and feel pretty well throughout the day, I am very active, I continue working (not from the office, working from home now only, but still...), I do lots of stuff around the house, I work out for at least an hour every day. Then the evening comes and I suddenly feel so much heavier and more uncomfortable. Can’t find a right position to sit or lie down. And then sleepless nights begin. I can stay awake for hours and hours and then suddenly I am comfortable again early in the morning and can squeeze in a few hours of decent sleep then. I don’t get why is this happening and if anyone can relate and has some tips, they are all welcome. Let me add that I eat a very healthy diet, I make sure I don’t overeat in the evening, I don’t drink coffee, In general I have not put much weight on and I am not even that big for 8 month of pregnancy.