4. It can increase your energy levels
I Believe that when you are on summer break your less stressed you don't have to worry about things. If someone has an actual medical issue say if you have seizures' you'd rather be at home than worrying about it at school. I hope this helped.
I'd say keeping the T cell count high because these are the cells that fight viral infections (HIV is one of them).
Answer:

Hope it helped,
Happy homework/ study/ exam!