It's not a dichotomy, both is good. I find my sleep and appetite improving with exercise, too; sleep can improve with physical tiredness on top of mental.

It's a shame how strong the reinforcement loops are. It's hard to sleep well without good exercise, and it's hard to exercise well without good sleep.

The more you age, the more you need regular sleep, it seems. Its basically the only thing that I can't fix nowadays any other way but going to bed. Modafinil can help for a couple of days but that's it.