 The primary psychological effects have a duration of roughly 3 to 4 hours, with aftereffects such as tachycardia, hypertension, and mild stimulation lasting from 6 to 8 hours.High doses have been observed to cause intense, prolonged panic attacks in stimulant-intolerant users, and there are anecdotal reports of psychosis from sleep withdrawal and addiction at higher doses or more frequent dosing intervals.It has also been repeatedly noted to induce irresistible cravings to re-administer.