I have struggled with sleep my whole life. I can't sleep, I'm a light sleeper and I almost always wake up tired. Not long ago I started making massive changes to help myself sleep. I get up early, I don't eat late and no screens a few hours before bed and I'm good. If I'm worried about things, I write out a list on paper so "I won't forget about them".
If I exercise I get better sleep, if I eat a good diet I get better sleep.
Not sure we need an app for sleep. It kinda feels like a solution looking for a problem.