The following are present in patients in a vegetative state: Signs of an intact reticular formation (eg, eye opening) and an intact brain stem (eg, reactive pupils, oculocephalic reflex) Sleep-wake cycles, not necessarily reflecting a specific circadian rhythm nor associated with the environment More complex brain stem reflexes, including yawning, chewing, swallowing, and, uncommonly, guttural vocalizations Sometimes arousal and startle reflexes (eg, loud sounds or blinking with bright lights may elicit eye opening) Sometimes watering and tearing of the eyes Sometimes the appearance of a smile or frown Spontaneous roving eye movements—usually slow, of constant velocity, and without saccadic jerks The spontaneous roving eye movements may be misinterpreted as volitional tracking and can be misinterpreted by family members as evidence of awareness.