My friend Babu does Yoga during studies.
Step 1: Sit with a book on the bed. Feel comfortable; adjust your posture if required. Take deep breaths.
Step 2: Slowly extend your legs, scratch your stomach; curse your teacher and university for introducing such a subject.
Step 3: Lie down completely, let the book rest on the pillow and you rest on the bed. If anybody complains that you are not studying, show sthemthe book; stare at the book till they get out of the room.
Step 4: Closing the eyelids feels like heaven. Try it. A few seconds later, a dog barks and wakes you up. Curse the dog; resume staring at the book for few more minutes.
Step 5: Realise that closing the eyelids was not a bad idea at all. Postpone study time by 1 hour to round-off. Close your eyelids again to doze off
There is a huge difference between a comfortable position and a cozy position. One will let you study; the other will encourage you to sleep.
The body's habit when lying down is to relax and sleep. Why should we fight that tendency? In addition, lying down promotes passive reading and it is hard to take notes or type while lying down. So, students who study lying down are playing a less active role in their learning than those who study sitting up.
Sit on a stiff chair and never on the bed or sofa. Don't let the angle of view strain your eyes.
Studying On a Sofa or a Bed Will Make Johnny's Concentration Dead