Certainly there are hundreds if not thousands of channel/apps on Roku. However, quite a few of them do have inactivity timers and even those that don’t might add one at any time. Unlike broadcasting, each individual stream costs, so many companies don’t want to keep a stream going when no one is watching (the ads). For sleeping, you might want to use broadcasting (TV or radio) rather than streaming, or get one of those ambient sound generators that depend on nothing external to make noise all night. Then again, I notice that if I search for “sleep” in the channel store, quite a few sleep sound apps for Roku are listed.