Wakeful

(a.) Not sleeping; indisposed to sleep; watchful; vigilant.

Thesaurus Entries

agile, alert, alive, attentive, awake, bright, insomniac, insomnious, keen, nimble, on the, on the alert, on the ball, on the job, prompt, qui vive, quick, ready, restless, sharp, sleepless, slumberless, smart, unblinking, unnodding, unsleeping, unwinking, wide-awake