If you’ve reached perimenopause and suddenly feel like you just can’t handle stress the way you used to, you’re not imagining it. Maybe you’re waking up at 3:00 a.m. with your mind racing. You’re exhausted in the afternoon but somehow get a “second wind” at bedtime. Your anxiety feels heightened, your body composition is changing, or you simply feel more easily overwhelmed by things that wouldn’t have rattled you a few years ago. There are many reasons this can happen during the menopause transition, but one important piece of the puzzle is cortisol.