The Furby Boom, like older Furby models, has no off switch to make it go to sleep. The Furby Boom can be put to sleep by pulling its tail for ten seconds or setting it on its back for 15 seconds or longer. Older models will not have those sleep options, but any Furby will eventually doze off when left in a quiet place.
Furby Sleep Time
Any Furby model gets sleepy if you place it in a quiet area and do not move it. Furby is ready for sleep when it makes snoring sounds. Leave it alone when it snores and it will go to sleep. The Furby Party Rocker model may also be turned off via app, by selecting the "Lulla Baah" feature. Another way to make any Furby go to sleep quickly is to remove its batteries. If the Furby doesn't wake up when you play with it or make noise near it and it has good batteries inside, remove its base and press the exposed "refresh" button for two seconds.