There are 2 ways I know when it’s ready for bed:

1. It’s a work night and it’s after 8:30.

2. just get randomly tired all of a sudden. There’s no working through it when I’m that way. If my favorite show is on I’ll just record the rest of it. No matter what time it is if I get suddenly exhausted I have to get to bed. I got suddenly
exhausted at work last Friday and I had to keep myself from literally napping on the floor.