Shellb, I can get like that after a break, the first time I go back. I was also exhausted at the end of the summer term. I don't know about HRT things, as I don't take them, but I carry Bach Flower Rescue Remedy and some lavender oil round with me during the day, and take Bach Flower Rescue Remedy-Night when I go to bed, or if I wake up in the middle of the night. The first one helps to keep me calm during the day, if I need to, and the second one helps me get to sleep in the first place and stops my mind from racing if I wake up in the middle of the night, so that I get a good/better sleep. That in itself helps me to get through the day.
I hope this is of some help. Good luck.