Wakeful, a.
Not sleeping; indisposed to sleep; watchful; vigilant. Dissembling sleep, but wakeful with the fright. Dryden. -- Wake"ful*ly, adv. -- Wake"ful*ness, n.
Shades of meaning
Fernald has no entry of its own for wakeful; he lists it under vigilant.
Where he writes about it:
A person may be wakeful because of some merely physical excitement or excitability, as through insomnia; yet he may be utterly careless and negligent in his wakefulness, the reverse of watchful; a person who is truly watchful must keep himself wakeful while on watch, in which case wakeful has something of mental quality. — from vigilant