The Collaborative International Dictionary of English v.0.48:

Sober \So"ber\, v. t. [imp. & p. p. Sobered; p. pr. & vb. n.
   Sobering.]
   To make sober.
   [1913 Webster]

         There shallow draughts intoxicate the brain,
         And drinking largely sobers us again.    --Pope.
   [1913 Webster]