When I was doing exams at uni, I would minimise non-essential tasks as much as possible so I could have more time to wind down. I would switch to having ready meals rather than cook, kept cleaning to a minimum (i.e. just doing dishes), made sure I had healthy snacks stocked up in advance. I would also make sure to go somewhere else to study for at least part of the day so I could get some fresh air on my walk. If I got stressed, I would go out for a run and that helped loads to calm me down.
When on study leave, I let my circadian rhythm do its thing, which often meant I would be staying up to study until 2-3am (don't recommend this but I've always had more energy in the evening so I would maximise this by studying at night), but I would always let myself sleep as much as I needed - this meant getting up at 11, but so be it.
And, this was never planned, but if I ever started procrastinating, I would let myself do it for a while to give my brain a break and didn't allow myself to feel guilty for it. I always got through the revision I needed and passed my exams, so clearly this is what my brain needed.