I read about sleep disorders and in the report there were also results, not only about smart devices, but also about radiation in general and how it affects the well-being during the sleep phases.
You are doing exactly the right thing with your smart phone, but if you want to go one step further, you can also set your WiFi router to sleep mode, as the radiation from WiFi has a huge impact on our sleep behavior.
It is also highly recommended, as professional athletes do, to completely darken the room to minimize light sources. Even small stand-by lamps are switched off or taped over by Olympic athletes, for example.
I found the reportage really crazy about all the things that have an influence on us and what we don't even pay attention to or know about.