hey! ive struggled with a little insomnia in the past, and the best solution for it is literally routine. i know with adhd one’s concentration can fluctuate, but to help yourself, try making something fun a habit! your mind should get familiar with what you’re trying to achieve, whether it is studying for your exams, or simply even regulating your sleep. one way to tackle insomnia is busying yourself with something since you will naturally get tired, and to tackle adhd, allow yourself breaks to wonder! don’t go into turbo mode, simplify your routine, believe in your capability. exams come and go, the score doesn’t matter, if you give your best then your score wouldn’t bother you.
if you allow yourself to work efficiently, your body and mind will itself quiet down and want rest, and with breaks, you can allow your inspiration to breed on its own.
try things like exercising or cut off distractions as much as possible, honestly that’s all the help I can offer. I wish you the best for your exams! im sending love <3