OP, I'm exactly where you are. I used to enjoyed going to work. Yes, it was tiring working FT with young children, but when I got to work, I could emerge myself in my duties, and get some pleasure in what I was doing, glad for a distraction. I enjoyed the social interaction, the mental challenge, the satisfaction of getting praise.
Then the menopause hit and suddenly, I found it harder and harder to do the things I took for granted before. My concentration went down the pan, started to get anxiety attacks at meetings, couldn't bear the noise in the office, and just became overwhelmed with it all. I've changed jobs and things are much better now. I can't fault anything about the job, I do enjoy the role, but it is just too much. The menopause has shattered my sleep, and this in turn means that my mental energy is significantly reduced and minimal concentration leaves me shattered. I struggle to get on with my job, yet any stimulation around me overwhelms me.
Work has become something I just cope with on a day to day basis. It frustrates me so much because I should enjoy it and get satisfaction from it, but except for the first two weeks after a holiday, it is just a case of counting the days until the week-end.
It doesn't help that most of my friends work PT and some not working at all, and they seem to have so much more energy than I do. There is so much I enjoy doing outside of work, that make me feel better, and lead me to better night sleep too, it is very frustrating.
It's life though, so I'll keep going and be grateful of the advantages that come with my work. Hopefully I'll be able to drop a day in a year's time or two and I hope to retire by the time I'm 60 which is so much better than others can hope for.
The menopause is nasty business. I expected it to come with unpleasanteness but not to impact on me to that extend that I can't get some satisfaction at work like I have done all my life until now. When it depresses me, I remind myself that they are indeed many women who feel like us.