Kiddo has trouble falling asleep

My son (7 y.o.) has been having trouble going to sleep. The first four or five years of his life, he went to sleep like clockwork, but sometime a year or so ago, he started complaining of being afraid of the dark. At first, I stayed in his room until he fell asleep, but he'd try to talk and play, so I had to ignore him and remind him to go to sleep. After a week or two, I decided that this wasn't sustainable, so I told him that monsters aren't real and that he's safe. He'd still burst out of his room, make some excuse for why he popped out of his bedroom. At some point, it felt like he was no longer really scared of the dark, but now has FOMO or a busy brain. Does anyone have suggestions for handling either one?