Source : Webster's Revised Unabridged Dictionary (1913)

Sleepless \Sleep"less\, a.
   1. Having no sleep; wakeful.

   2. Having no rest; perpetually agitated. ``Biscay's sleepless
      bay.'' --Byron. -- {Sleep"less*ly}, adv. --
      {Sleep"less*ness}, n.

Source : WordNet®

sleepless
     adj 1: experiencing or accompanied by sleeplessness; "insomniac old
            people"; "insomniac nights"; "lay sleepless all
            night"; "twenty watchful, weary, tedious nights"-
            Shakespeare [syn: {insomniac}, {watchful}]
     2: without having the eyes closed or covered by the eyelids;
        "to an eye like mine, a lidless watcher of the public
        weal"- Alfred Tennyson [syn: {lidless}]