I reckon this is a great idea. Sleep ASMR videos are already pretty good as they are. If you have some videos where people are counting down, it’s like a reverse sheep counting exercise that people sometimes do (also to fall asleep). Also, it’s done by someone else, so you don’t have to put in the effort to count yourself.

There’s a few of these on YouTube, so see what works for you but they’re pretty straightforward tbh. It probably just comes down to personal preference and who you might like to be counting down. Maybe you prefer a female to a male voice? I can’t seem to find many dudes doing it, just more females, maybe you can help?