An implantable neurostimulator-implemented method for managing tachyarrhythmias upon a patient's awakening from sleep through vagus nerve stimulation is provided. An implantable neurostimulator, including a pulse generator, is configured to deliver electrical therapeutic stimulation in a manner that results in creation and propagation (in both afferent and efferent directions) of action potentials within neuronal fibers comprising the cervical vagus nerve of a patient. Operating modes of the pulse generator are stored. An enhanced dose of the electrical therapeutic stimulation is parametrically defined and tuned to prevent initiation of or disrupt tachyarrhythmia upon the patient's awakening from a sleep state through at least one of continuously-cycling, intermittent and periodic ON-OFF cycles of electrical pulses. Other operating modes, including a maintenance dose and a restorative dose are defined. The patient's physiological state is monitored via at least one sensor to detect that patient's awakening, which activates the delivery of the enhanced dose.