The Collaborative International Dictionary of English v.0.48:

Noctambulism \Noc*tam"bu*lism\, n.
   Somnambulism.

   Syn: sleepwalking; noctambulation.
        [1913 Webster]

WordNet (r) 3.0 (2006):

noctambulism
    n 1: walking by a person who is asleep [syn: sleepwalking,
         somnambulism, somnambulation, noctambulism,
         noctambulation]