It is said that the effect of eating too much lettuce is "soporific."
I have never felt sleepy after eating lettuces; but then I am not a rabbit.
They certainly had a very soporific effect upon the Flopsy Bunnies!
These, for those who don’t recognise them, are the opening lines of one of my childhood favourites - The Tale of the Flopsy Bunnies by Beatrix Potter. They also mark one of the first times I became aware of how some words roll around the mouth in a pleasing way and somehow manage to convey so much more than others. Soporific remains one of my favourite words, partly because of its significance in the start of my love affair with language, but also because it’s used so rarely, despite expressing an apparently basic concept for which there is no simple synonym. So when it does crop up, it somehow gives all the more pleasure!