somniferous

I did not find the jolting of the cart at all disagreeable; on the contrary, it had quite a somniferous effect upon me.

This yelp, sounding above the somniferous monotone of grumbling, stirred Cap'n Sproul from his dozing.

They were aware of the somniferous properties of the sap, and Dioscorides2005 mentions the variety with white seeds.

It was of a remarkably somniferous character,—the cunning Le Duc had evidently some object in playing thus.

Night otherwise fallen dark and somniferous to modern mankind.