agrypnotic

from WordNet (r) 3.0 (2006)

agrypnotic
    adj 1: of or pertaining to agrypnia

from The Collaborative International Dictionary of English v.0.48

Agrypnotic \Ag`ryp*not"ic\, n. [Gr. ? sleepless; ? to chase,
   search for + ? sleep: cf. F. agrypnotique.]
   Anything which prevents sleep, or produces wakefulness, as
   strong tea or coffee.
   [1913 Webster]