How Does Stress Affect The Body?

To understand what stress does to us, imagine you lived tens of thousands of years ago, at a time when humans were threatened by hungry animals such as saber-toothed tigers and wolves. Our caveman ancestors had to be able to react instantly, either by fighting the beasts or running away.

So humans evolved the ability to respond to a stressful situation instantly, by preparing the body for "fight or flight." Under sudden stress, you will get a burst of exceptional strength and endurance, as your body pumps out stress hormones:

• Your heart speeds up

• Blood flow to your brain and muscles increases up to 400 percent

• Your digestion stops (so it doesn't use up energy that's needed elsewhere)

• Your muscle tension increases

• You breathe faster, to bring more oxygen to your muscles

Sometimes we can still benefit from this "fight or flight" response - like the case of a mother whose child was pinned under a concrete slab during a tornado. Under stress, she found the strength to lift the huge slab with her bare hands, even though it later took three men to move it.

But much of the time in modern life, the "fight or flight" response won't help. Yet those stress hormones still flood your system, preparing you for physical action. And if you are under stress frequently, it can harm your physical health.