Anxiety disorders are medical conditions that strike nearly 30% percent of adults at some point, according to the American Psychiatric Association.

One prominent sufferer is Eagles lineman Brandon Brooks, who left Sunday’s game against the Seattle Seahawks as a result. In a tweet, he described how he went through his “typical routine of morning vomiting,” which did not go away as usual.

An anxiety disorder is defined as having feelings of fear or anxiousness that are out of proportion to the situation — to the point that they hinder a person’s ability to function normally, the psychiatry association says.

Such conditions include specific phobias, panic disorders, and more generalized sensations of debilitating anxiety. Most can be managed with treatment, which can include talk therapy and medication. Brooks has tried both.

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The causes of anxiety disorders are not fully understood, but are thought to involve a combination of genetic and environmental factors. Such disorders can run in families, the association said.

Brooks disclosed his condition to the public in December 2016. He has said that some teammates were skeptical at first, but they eventually became supportive.