Burnout is now officially recognized as a medical condition. Here are the symptoms you should know about.

REUTERS/Philippe Wojazer

Burnout results in "increased mental distance from one's job" and "reduced professional efficacy."

• Burnout (exhaustion due to chronic workplace stress) has been defined by the WHO as a clinical syndrome.
• Cases of burnout have been increasing at an alarming rate over the years, and the new classification is bringing attention to workplace stress.
• Doctors are among high-stress professions that experience burnout twice as often as the average American worker.
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If you've ever had an ache somewhere in the back of your head at the end of a long workday, or you sometimes lose the ability to concentrate after too many hours at your desk, you've likely had a case of burnout- and you're not the only one.

The World Health Organization (WHO) recently classified burnout as a "syndrome," medically legitimizing the condition for the first time.

According to the WHO's International Classification of Diseases (the ICD-11) chart, burnout results from "chronic workplace stress that has not been successfully managed." The ICD lists possible signs of burnout as:

1) Feelings of energy depletion or exhaustion.

2) Increased mental distance from one's job, or feelings of negativism or cynicism related to one's job.

3) Reduced professional efficacy.

Even though burnout seems like a recent phenomenon, psychologists have been studying the feeling for the last four decades. According to CNN, American psychologist Herbert Freudenberger coined the term in 1974. Since then, hundreds of studies have attempted to explain the disorder, likening it to anxiety or mood disorders. Severe cases of burnout, according to one study, actually stem from depression.

High-stress professions such as doctors are burning out twice as fast as the average American worker, and the US is paying billions of dollars as a result. Doctors (over half of whom experience burnout) leave healthcare systems that flood them with too many patients, putting a strain on the system.

Workers in the United Kingdom are feeling burned out as well. A study by the Health and Safety Executive (HSE) found that 526,000 UK workers suffer from burnout, and that 12.5 million workdays were lost from 2016 to 2017 as a result.

Burnout has become a bigger issue in recent years, and now that it's classified as a mental disorder, employers may take steps to mitigate it, or prevent it from occurring altogether.