Answer:
the answer is by examining their study habits, but all of these factors contribute in one way or another. for example, if you don't get enough sleep you won't be as aware as you should be, if you're not watching your diet and what you eat it can be detrimental to your health, like how too many sweets can cause cavities and diabetes(although diabetes is also genetic) or if you are abusing things like drugs or alcohol, it could be potentially fatal. physical activity is also important because it get your heart rate up and blood pump makes you alert and raises your mood. so all four factor in at some point, and losing any is terrible for anybody. the answer you are probably looking for is: by examining their study habits.