carefully observant or attentive; on the lookout for possible danger; "a policy of open-eyed awareness"; "the vigilant eye of the town watch"; "there was a watchful dignity in the room"; "a watchful parent with a toddler in tow"
(of sleep) easily disturbed; "in a light doze"; "a light sleeper"; "a restless wakeful night"
carefully observant or attentive; on the lookout for possible danger
