Hello~It could be a form of "hot flashes" I don't know your age, but as we near peri-menopause and menopause, our hormones can play some weird tricks on us and the hot flashes are definitely one of them. There really is no set pattern for having the either.
If they continue or get worse, then see your GYN, he/she will be able to take some tests and tell what plan of action to follow. In the meantime, I suggest going to your local health food store and purchasing "Bio-identical" progesterone cream. This is all natural, the same as your body would make, follow the instructions and maybe this will help, I know all ages can use it, and it helps so much more than just the "flashes" such as sleep, moods, etc.