I'm going to ask a more generic question: pre-exams, did you have trouble switching from work-mode to home-mode, to stop thinking about work and relax/think about home things? Or on non-study days, do you have trouble doing that? If not, then I'd consider what helped you turn off work-home on non-study days and try to implement those same methods on study-days. If you had the same issues on non-study days, then your “problem” is bigger than just a study-related one.
Myself, I've always struggled to turn off work-mode after I left work. My dad was a bit of a workaholic and I “inherited” a full dose. 😐 I've learned to be better with it, but it's taken awhile. The first step for me was to not talk about work outside of work, aside from isolated brief stories. My boyfriend helped a lot with this – after a couple minutes of work stories, he'd tell me to stop thinking about work cause I was home now. Not talking about work helped me to think less about work. When I'm really struggling, resetting my mind is very helpful. One (albeit slightly uncomfortable) way to do that is to take a cold shower. Short of that, any shower/bath at all can help. Some people like to take a run or jog for the same purpose. Something about these types of activities seems to help many people to clear their mind out and start fresh. A short nap could also serve the same purpose, but I can't nap in the evening or I won't sleep at night, and I can't nap easily when I'm stressed about work, either. 😐
So I guess my simple steps would be a) don't talk about work outside of work and b) use some sort of mental re-set (shower, esp cold, or quick run/jog that your mind isn't focused on work) to clear work out of your mind and prepare for something else.
In time it gets easier. Most evenings now, I can go home and within a short time switch focus to home-life instead of work-life, without having to do anything to especially change modes, but a shower or bath is still a good way for me to change my focus when work is too stressful or all-consuming for it to change naturally.
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