Lewis Short
(adjective) : ex-somnis (exomn-), e, somnus
* Sleepless, wakeful, watchful (poet. and in post-Aug. prose; cf.: insomnis, vigil, vigilans): vir,Vell. 2, 88, 2: (Tisiphone) Vestibulum exsomnis servat noctesque diesque,Verg. A. 6, 556; Sil. 9, 5: animo exsomnis,Vell. 2, 127 fin.
Charlton T. Lewis, Charles Short, A Latin Dictionary