What Causes Fatigue? The Stress Factor

You’re fatigued, but why? A variety of factors can cause you to feel overtired. Here, we focus on a major “stressor”—and offer hope.

what causes fatigue

Falling asleep even as you wonder what causes fatigue? There are some basic steps you can take to help you get your energy back, as we discuss here.

© Carolyn Franks | Dreamstime.com

You’re always tired but you haven’t been able to pinpoint the reason. You think about embarking on a campaign to get to the bottom of your fatigue, but—sad to say—you don’t have the energy to follow through. Don’t feel bad; even the medical community doesn’t fully understand what causes fatigue.

Researchers do understand, however, that fatigue is fairly common. It is thought to affect around 30 percent of the U.S. population, and more than 1 million people have been diagnosed with chronic fatigue syndrome, according to the Centers for Disease Control and Prevention.

Researchers also know that fatigue in individuals often results not from a single cause but from a complex set of factors. Countless variables—sometimes unidentifiable ones—can conspire to create fatigue. One of the most common: stress.

What Causes Fatigue? For Starters, Stress

The National Institutes of Health defines stress as, simply, “the brain’s response to any demand.” Stress points come at us from all directions: work, illness, relationships, finances, and major life events like relocation, job change, marriage, and divorce, among many others. We may experience stress symptoms just from reading international news (terror attacks, for example, or natural disasters) or from personal disappointments (a broken friendship, for instance, or feeling overlooked at work).

Sometimes, multiple stressors can hit us at the same time, and they can compromise our sleep schedule, diet, and ability to exercise. All of these stress points can pile on to create that seemingly inescapable fatigue.

fight or flight

Fight or flight: That’s the choice our bodies often make, instinctively, when pressed with multiple stressors.

When dealing with multiple stressors, our bodies instinctively go into “fight or flight” mode, releasing adrenaline, increasing heart rate, and/or disrupting the digestive system. We commonly feel our muscles tense up—a natural response in which our body instantly prepares to protect itself from pain or injury.

The worse the stress gets, the less we’re able to focus on solutions—even ones that would seem obvious (regular sleep and invigorating, stress-reducing exercise, for example).

Where’s the Defense?

In high-stress situations, the main components in our natural defense mechanisms—the brain, nervous system, hormonal (endocrine) system, immune system, and adrenal glands—can be compromised.

The hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) are our key regulatory centers. Inadequate regulation of these stress-response systems causes chronic stress. Adrenal fatigue is especially common with people who experience prolonged and intense stress.

“As the name suggests,” according to AdrenalFatigue.org, “its paramount symptom is fatigue that is not relieved by sleep, but it is not a readily identifiable entity like measles or a growth on the end of your finger. You may look and act relatively normal with adrenal fatigue and may not have any obvious signs of physical illness, yet you live with a general sense of unwellness, tiredness or ‘gray’ feelings. People experiencing adrenal fatigue often have to use coffee, colas and other stimulants to get going in the morning and to prop themselves up during the day.”

Without taking steps to turn the tide of adrenal or stress-related fatigue, we find our energy consistently sapped.

Stress-induced fatigue symptoms vary and can include any or all of these conditions: headaches, sweating, backache or neck pain, temporomandibular (jaw) pain, nervous disorders, breathing issues, high blood pressure, ulcers, skin condition, depression, or dizziness.

We also may experience a loss of appetite (and resulting unintended weight loss) or, conversely, a binge-eating disorder (with unintended weight gain). Women can experience premenstrual or menstrual disorders, and men can experience erectile dysfunction. Forgetfulness and restlessness also can result from stress.

Beat Stress-Related Fatigue: Three Starting Steps

It’s not practical or realistic to believe we can remove stress—and the resulting fatigue—from our lives. But it is possible to relieve it, and to become more irrepressible.

Try these three proactive ways of handling stress, each of which gives you a better chance of overcoming fatigue.


It may be hard to get started on an exercise routine when you’re feeling constant fatigue, but once you get going, it will become a

worthwhile part of your lifestyle.

1. Exercise regularly (low-impact to start). A review by the Agency for Healthcare Research and Quality found that exercise may help relieve fatigue and improve the quality of life for people with chronic fatigue syndrome. Exercise decreases stress hormones, releases “feel-good” endorphin hormones, and relaxes your muscles. You’ll sleep better at night, and you’ll feel less fatigued.

The key: Make up your mind to start, and then get into a consistent exercise routine, beginning with light and low-impact types. The more severe your fatigue—especially if it has evolved into chronic fatigue syndrome—the more important it is to manage your physical activities.

The Centers for Disease Control and Prevention encourages us to “Get motivated!” and recommends starting slowly, and “work(ing) your way up to more physically challenging activities.” (See also our post “How to Get Motivated to Exercise.“)

At the very least, walk—a 20- or 30-minute brisk walk twice a day, or at least once a day—makes a difference. If the weather isn’t cooperating, visit a gym or a shopping mall and walk there. It’s the easiest way to get exercise and start you on the path to beating stress-caused fatigue. Our post “The Benefits of Walking” may help. Yoga also makes for a beneficial exercise routine; see our article “Yoga for Beginners.”

2. Fix your diet flaws. Most of us cave in to “wrong” food choices now and then—that Boston cream at the donut shop, the bag of chips, the sugary ice cream. But keep in mind that in order to beat fatigue, your best bet is to eat a diet high in fruits and vegetables (which provide vitamins, minerals, and phytonutrients) and avoid high-fat, high-glycemic, inflammatory foods. Glycemic index, or GI, measures how a carbohydrate-containing food raises blood glucose, according to the American Diabetes Association. Foods are ranked based on how they compare to a reference food—either glucose or white bread. A food with a high GI raises blood glucose more than a food with a medium or low GI. (See University Health Center’s quick-reference Glycemic Index chart by clicking here.)

Avoid too much caffeine by cutting out energy drinks, colas, chocolate, and other generous sources. In fact, experts have suggested that people who are fatigued might try going three weeks without caffeine. Combined with healthy eating and regular exercise, you may find that it plays a role in restoring that missing energy by helping you sleep at night.

3. Find a better balance. You likely had a time in your life where you felt like you had a reasonable balance. Think about what recent demands have been robbing you of that balance. Have you taken on too many new tasks, interests, or commitments that by themselves are meant to be relaxing but—totaled together—have become stressful?

For example, if you feel stretched thin by your volunteer work, regular wine-and-cheese outings with friends, and time-consuming hobbies, cut some of them out for a while. You’ll give yourself more time to devote to work and family responsibilities, to get the regular exercise we mention above, and reduce stress.

Originally published in 2016, this post is regularly updated.

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Larry Canale

Larry Canale has been editorial director or editor-in-chief of a number of launches in the areas of consumer magazines, newsletters, and websites for Belvoir Media Group. Since early 2019, he … Read More

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