What stress does in your body

When your brain sees a threat, such as an exam, a hard conversation or a rejection email, it triggers the stress response, often called fight or flight. Hormones such as adrenaline and cortisol speed up your heart and breathing, tense your muscles and push blood to where you would need it to run.

Digestion slows, which is why you may feel sick before a presentation. This system kept our ancestors alive, and in short bursts it is useful: it sharpens attention. The problem is that the body reacts the same way to a deadline as to real danger, and modern stress often does not end.