I once heard that R’ Moshe Feinstein Zatza”l said that he thanks Hashem every day when he wakes up not only for letting him wake up (modeh ani- shehechzarto bee nishmosi), but also for letting him fall asleep right away. He added that as long as he can remember he was blessed with the ability to fall asleep as soon as he lay down.
The brocho of “Hamapil” is exactly for that! Thanking Hashem for making you fall asleep! [Maybe Hamapil is like a “brocho rishona” (brocho before eating), and thanking Hashem in the morning for the sleep is like a “Brocha Achrona” (like bentching, borei nefoshos, al hamichya etc.).
Try saying Hamapil with kavanah! (don’t worry about not being able to talk after hamapil if you don’t fall asleep, there are those who hold that if you tried to sleep and can’t it’s not a brocho levatala and you can talk).
If we show Hashem that we appreciate it then he might give us the ability to sleep better, like in the case of R’ Moshe.
Good luck, and sleep well!