I've been able to fall asleep anywhere, anytime for most of my life. Last year or so something flipped. I've taken to listening to audiobooks or history podcasts or lowkey videos of, like, watchmaking or book binding. Have a Bluetooth thing under my pillow and if I focus on visualizing the story or activity I will fall asleep instead of replaying some shitty thing that happened to me this week. Or 20 years ago. Or might happen tomorrow. Or what someone thinks about something I thought about. Or that thing I need to remember to do but know I won't.