What I have observed (in my case) is that if 1. I am too tired, it actually takes longer to fall asleep. 2. If I have watched some heavy / thought provoking movie / series etc., those thoughts keep playing out in my head and then it takes longer to fall asleep.

In such cases, I have devised a strategy. I have developed a fantasy of my own which I keep playing out in my head consciously. I am fast asleep before I know it.