somnambulism
Concise Oxford English Dictionary © 2008 Oxford University Press:
somnambulism /sɒmˈnambjʊlɪz(ə)m/
▶noun sleepwalking.
– derivatives
somnambulant adjective
somnambulist noun,
somnambulistic adjective.
somnambulant adjective
somnambulist noun,
somnambulistic adjective.
– origin C18: from Fr. somnambulisme, from L. somnus ‘sleep’ + ambulare ‘to walk’.
'somnambulism' also found in these Oxford entries:

