somniferous
adj 1: sleep inducing [syn: {soporific}, {soporiferous},
{somniferous}, {somnific}, {hypnogogic}, {hypnagogic}]
Somniferous \Som*nif"er*ous\, a. [L. somnifer; somnus sleep +
ferre to bring.]
Causing or inducing sleep; soporific; dormitive; as, a
somniferous potion. --Walton.
[1913 Webster]