Tending to induce sleep; soporific:lifeless actors made the experience even more somniferous for the audiences...
They all indulge in their familiar, somniferous spiels.
This book helps put aside what the late Prof. Takaaki Aikawa described as the ‘somniferous romanticism’ with which the Westerner approaches Japanese studies.
In somniferous mumbles, he reads aloud the entire song.
Origin
Early 17th century: from Latin somnifer (from somnium 'dream') + -ous.