My HormonologyThink everything about your premenstrual Week 4 is negative? Not so! A recent study reveals that plunging estrogen creates changes in the brain that amp up both anxiety and awareness of your environment, making you better at spotting danger. While the researchers specifically focused on how fast women see snakes, this can also apply to how quickly you notice other potentially life-threatening problems that suddenly pop up, such as a car veering into your lane, a brawl breaking out in a bar or an open grate on the sidewalk!