Some couples sleep at the same time. Some don't.
It's encouraging to show your partner it's time to sleep. People like doing the same things together, so they'll agree to do something if you do it too.
By showing your partner it's time to sleep you're checking all the right boxes at the right times; happy partner, thinking clearly, positive outcomes, reaping what you sow, thinking ahead.
I won't however, sleep for me and wake for you. I don't know what's best for me, so I'll go to bed late. Then I'll find it hard to wake, be tired, not thinking straight.
It's easier to know what's best for you.
I'll sleep for you, so you know it's time to sleep. And I'll wake for me, with the extra time to keep.