Coming in late on this, but just wanted to mention that this is a frequently discussed topic in the forums, there are at least four threads on it. Bedrooms are always tricky because of the amount of time that people spend lying still watching TV or reading which can then register as inactivity on a motion sensor. Or the inverse, where someone moving in their sleep registers as activity.
Different people solve it differently depending on their exact circumstances. You can use custom code if you like, but it often isn’t needed. People have had solutions for this issue since before rule machine ever existed. But most of the solutions involve carefully analyzing which devices you need where… 
Here’s one recent thread to get you started – – it includes links to several of the other threads as well, so it should give you a lot of ideas.