Jack was sitting, reading a book when all of a sudden he felt he was "losing his mind." his heart beat faster and he began to sweat and tremble. his behavior mostly resembles disorder

panic anxiety

Explanation:

Panic anxiety occur unexpectedly, sometimes even when waking up from sleep characterized by its unexpectedness and debilitating, immobilizing intensity it is caused by Severe stress, such as the death of a loved one, divorce, or job loss can also trigger panic anxiety. Panic attacks can also be caused by medical conditions and other physical cause e.g sitting in a position for hours under an unfavorable condition doing a recurring activity.  Panic anxiety may occur as part of another disorder, such as panic disorder, social phobia, or depression. Regardless of the cause, panic attacks are treatable.

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