Source : Webster's Revised Unabridged Dictionary (1913)

Wakeful \Wake"ful\, a.
   Not sleeping; indisposed to sleep; watchful; vigilant.

         Dissembling sleep, but wakeful with the fright.
                                                  --Dryden.
   -- {Wake"ful*ly}, adv. -- {Wake"ful*ness}, n.

Source : WordNet®

wakefulness
     n 1: a periodic state during which you are conscious and aware of
          the world
     2: a temporary state in which you are unable (or unwilling) to
        sleep [syn: {sleeplessness}] [ant: {sleepiness}]