When you encounter a perceived threat — such as a large dog barking at you during your morning walk — your hypothalamus, a tiny region at your brain's base, sets off an alarm system in your body. Through a combination of nerve and hormonal signals, this system prompts your adrenal glands, located atop your kidneys, to release a surge of hormones, including adrenaline and cortisol. 

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Adrenaline increases your heart rate, elevates your blood pressure and boosts energy supplies. Cortisol, the primary stress hormone, increases sugars (glucose) in the bloodstream, enhances your brain's use of glucose and increases the availability of substances that repair tissues.

Cortisol also curbs functions that would be nonessential or harmful in a fight-or-flight situation. It alters immune system responses and suppresses the digestive system, the reproductive system and growth processes. This complex natural alarm system also communicates with the brain regions that control mood, motivation and fear.

When the natural stress response goes wild, the body's stress response system is usually self-limiting. Once a perceived threat has passed, hormone levels return to normal. As adrenaline and cortisol levels drop, your heart rate and blood pressure return to baseline levels, and other systems resume their regular activities.

But when stressors are always present and you constantly feel under attack, that fight-or-flight reaction stays turned on.  This long-term activation of the stress response system and the overexposure to cortisol and other stress hormones that follows can disrupt almost all your body's processes. This puts you at increased risk of many health problems, including:

• Anxiety

• Depression

• Digestive problems

• Headaches

• Muscle tension and pain

• Heart disease, heart attack, high blood pressure and stroke

• Sleep problems

• Weight gain

• Memory and concentration impairment

That's why it's so important to learn healthy ways to cope with your life stressors.