WordNet sense 1 (condition of heightened watchfulness or preparation for action):

qui vive

WordNet sense 2 (a warning serves to make you more alert to danger):

alerting

WordNet sense 3 (an automatic signal (usually a sound) warning of danger):

alarm, alarum, warning signal

WordNet sense 4 (having the capacity for thought and reason especially to a high degree):

intelligent

WordNet sense 5 (not unconscious; especially having become conscious):

awake

WordNet sense 6 (knowing and perceiving; having awareness of surroundings and sensations and thoughts):

conscious

WordNet sense 7 ((usually followed by `to') showing acute awareness; mentally perceptive):

alive

WordNet sense 8 ((sometimes followed by `of') having or showing knowledge or understanding or realization or perception):

cognizant, cognisant

WordNet sense 9 (without having the eyes closed or covered by the eyelids):

sleepless

WordNet sense 10 (carefully observant or attentive; on the lookout for possible danger):

vigilant, watchful