Lateral hand numbness has the following two main reasons: first, physiological, the human body when lying on its side unilateral limb to bear the pressure of the entire limb, so it will cause the arterial blood supply is affected, the blood flow is slow, so the blood supply to the fingers is relatively reduced, and the fingers are the most sensitive as well as the most sensitive parts of the human body, when there is a temporary blood supply is affected, there will be numbness of the fingers, when the numbness is significantly relieved after getting up or activity;. Secondly, the cervical disc will cause a certain protrusion when the person is lying on his side, so there is a temporary compression of the nerve, which will also cause numbness in the hand, and the numbness is significantly improved after getting up or after the activity, if the numbness is not significantly improved after getting up and after the activity, consider the pathological reasons, there may be a protrusion of the cervical disc, to go to the hospital in time to do cervical spine nuclear magnetic clarification.