I have at 3 o'clock call as well.

At her office, corporate attorney Teresa Pahl deals with phone calls and emails deadlines and meetings.

There is always so much going on here. If I don't feed children, that's the disaster.

At home, mother of four Teresa Pahl deals with family meals—

The only thing that we haven't done is mom's coffee.

—children's schedules, clean up the kitchen—

What time do you want me to pick them up?

—drop off the kids, juggle some office emails, and don't forget the dog needs a walk.

When you know you've got a long list you just power through.

Our brains are designed to help us power through. Under stress, the brain signals to release hormones including adrenaline and cortisol. They give us energy, strengthen the immune system, improve reflexes, even help our memory.

What's the percentage on the maintenance?

But if we are always under stress, the release of cortisol begins to work against us.

Chronic stress affects your head, your heart, your liver, your immune system.

McEwen has discovered that chronic stress causes neurons in the brain to shrink and change shape. In animals, that causes a loss of memory, increased anxiety, and aggressiveness, and can lead to signs of depression. Other research has shown how chronic stress can speed up aging and make us more prone to disease.

Stress has been shown to affect almost every physiological system we have. And we've now shown that stress even affects cells at the molecular level.

Research has shown that telomeres, the protective coating at the end of chromosomes, gets frayed and worn by stress mimicking the effects of aging. In a world now filled with cell phones and BlackBerrys, instant messaging, and expectations of 24/7, our brains can get a stress signal every time an email comes in. Technology is creating new sources of chronic stress.

I actually had one of my partners walk into my office, and I looked at him and just said, what, what, what, what now?

Even those who manage stress well can sometimes be overwhelmed. Those who don't manage stress, psychologist Christina Maslach discovered, can reach a breaking point, burn out.

When people are experiencing burnout, they're more likely to make mistakes, make errors, they don't work as well.

But scientists say the brain's resilience can help prevent burnout.

The important thing to remember, though, is when we stop the stress, the neurons will go back to normal size.

The key is to give the brain time without stress, relaxing with family, exercising, eating well, and sometimes, just sometimes ignoring those emails.