If you’ve ever felt like your energy changed after 40 — or noticed that the things that used to work (fasting, exercise, or even a full night’s sleep) suddenly don’t — you’re not alone. There’s real science behind these shifts, and the key may lie in how estrogen interacts with the tiny energy factories inside your cells: your mitochondria. Let's take a look at the role of estrogen on the whole body, and how contrast therapy can support you through perimenopause and menopause