First of all stop taking stress , since stress is a number 1 cause for forgetting things even the simplest ones..since I can only assume that you are studying for 8 10 hours that means ur stressed either due to exams or something else and which is what is causing these issues ... Take a break from your schedule and meditate for at least 10 min in the morning when u wake up and go for at least 20 to 30 min of workout you shall start seeing the chnages.
Next Steps
take a break, exercise and meditate