I have really fragmented sleep like you where I wake up super early and can't fall back asleep. Melatonin helps me fall asleep but I sometimes wake up at around 4am and basically just lie in bed for an hour or two unable to sleep. There are theories that stuttering is linked to some brain chemical imbalance (dopamine) but from personal experience taking popular medications that are commonly talked about on this subreddit I found no real benefit and instead experienced mild depression and even worse insomnia. Just curious you take anything for your insomnia issue?