Disrupted Circadian rhythms only exacerbate the sense of dread that office politics, deadlines, and high-stakes projects can evoke. In the body, fear and stress start off similarly, prompting the body to release cortisol, a hormone that increases your heart rate and blood pressure, preparing you for a fight or flight response. But fear is acute—it passes, at least in theory, when the threat is gone, allowing cortisol levels to return to baseline. Stress, on the other hand, is prolonged. When cortisol is pumping through over veins for extended periods of time, it can wreak havoc on our organs.