Suss out medical causes through blood work, sleep study, etc. Work with your Dr on this.

Also work on sleep hygiene. Strict routime (go to bed and wake up at the same time every day), comfortable bed, cool dark room, preparation (nothing exciting, no screen use, no caffeine leading up to bed time), and mindset (we sometimes use headspace to help with bed time anxiety). My anxious kid has a weighted blanket and that helped him a lot.

Exercise during the day helps a lot with sleep and general well-being. I feel better and sleep better when I avoid sugar.

I don’t know how to learn decisiveness but I believe it can be learned through practice and I believe that being decisive helps you sleep. You know you did what you thought was right, there is less worrying about your decisions afterwards. My other son and I are this way and we sleep like babies. Speculation, there is definitely a correlation there for us so maybe it is causal.