A 44-yeаr-оld mаle is diаgnоsed with Generalized Anxiety Disоrder (GAD) and comorbid panic disorder. The psychiatric-mental health nurse practitioner decides to initiate a trial of Venlafaxine extended-release (ER) at 75 mg daily. During the pre-treatment counseling session, which physiological parameters must the clinician instruct the patient to monitor routinely at home, and what is the underlying neurobiological mechanism behind this specific clinical precaution?