Sleepless, 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.
Shades of meaning
Fernald has no entry of its own for sleepless; he lists it under vigilant.
He lists it without comment; the entries above explain its neighbors.