I am in my mid 40's and I only seem to have ample energy around the time of my cycle--what causes this?

Answer 1

Could be the onset of menopause. You can get your Dr to check this out for you.
There are simple remedies that you can take to boost your oestrogen levels. Soya being a good one. Red clover, and black cohosh may help, also agnus-castus.
Eating green veg and b6 will help remove oestrogen from your body.
There are other nutrients that you can take to help boost your energy levels. Rhodiola is one, as is a multi vitamin / mineral supplement.