Approaching 40...and menstrual cycle

Su

The last few months I’ve noticed a change in my ability to keep my hormones in check with I get my period. Like full blown crying and overreacting to silly things. I’ve never had too many issues with my menstrual cycle and even when I was pregnant I didn’t act like this. I had the random thought today that as I approach 40 (I’m almost 38), are my hormones just changing?? If so, this sucks. When does the body start to prepare for menopause?