At a certain point during your long study session there is the undeniable urge to take a break. Whether this break is only two minutes or 20 it is probably necessary.
However, if you only want a two minute break you probably shouldn’t check your Facebook. Instead you could get up from your desk, grab a healthy snack and eat it- before you return to studying. This will refresh your mind while getting you away from your desk, you’ll feel good about eating healthy and you avoided getting sucked into the Internet for who knows how long.
Now, I’m not saying this actually works for everybody, but it’s worth a try.
Good luck on midterms!