Whether it's a medication or a boring lecture, something somniferous makes you sleepy.
Like soporific, somniferous is a word used to describe something that puts you to sleep. Some people who have trouble snoozing take pills that are somniferous: sleeping pills. Others do somniferous things, like reading before bed or counting sheep. A bad public speaker can be really somniferous, and so can a boring movie. Anything somniferous makes you want to catch some Z's.