The Hot Springs in this videogame are by far the best way to recover stamina and to restore fatigue. For every in game minute that you're inside the Hot Springs you'll recover 2 stamina and have 1 fatigue removed.
You can stay up super late, jump in the Hot Springs for about an hour at around 4:00 am, run back to your farm and be in bed before 6:00 am. This will have a better effect on your stamina and fatigue than going to sleep at 6:00 pm and you'll be able to get a ton more work done each day.