North Pole of Earth & human head both are positive poles, due to which they repel each other. Flow of magnetic field is from North of South, so body in North South axis will receive magnetic field from the feet resulting in proper blood circulation, due to presence of iron in the blood.
When you are facing the North, the magnetic field of the Earth hits your face and charges you up resulting in sharp memory and increase in grasping power.
Face North while sitting in the toilet followed by south as a second option.