@Stef9998 said in not understanding Smart Sleep: @rejoe2 I'm in the process of configuring an OpenHab instance, and the binding should support smart sleep Don't know about OH's abilities, I "just" did the FHEM implementation of that feature . That I don't understand. Why should the controller have queued messages when the node is sending the second type (going to sleep). The controller knows the node is awake (cause of first/awake message), so why should it start to queue them? It should just send them, and then when the controller knows, that a node will be asleep (second message) start queueing. The user or some automatics could create some message to be sent out at any point in time. But sending out any message only makes sense when the controller knows the node is actually listening - these are sparse blinks in time, so most of the time a message will be queued first (or let's call it retained to stick to mqtt conventions). Then the controller has to wait for a signal from the node side, but as described earlier, this should not be the "awake" message (meaning a sensor can deliver some values and so on), but the "will go to sleep" one (meaning: "I will stop talking now, but continue to listen for 500 ms now"). Hope the fog is clearing now...