People with separation anxiety Disorder experience excessive fear or anxiety when they leave home or separated from major attachment figures (e.g., parents). They worry about losing major attachment figures (e.g., being kidnapped, die, becomes ill, getting accident). As a result, they may refuse to go out, to school, to work, etc. They often experience high level of fear or reluctant to be alone, away from attachment figures, sleep alone, etc. They may have repeated nightmares about separation and/ or repeated complaints of physical symptoms (e.g., headaches, stomachaches, nausea, vomiting).
Reference: American Psychiatric Association, 2013