Why numbness in thumb, index and middle finger on the right hand during sleep ?

Tingling: Pain, numbness, tingling, weakness and night pain are the most common symptoms of carpal tunnel syndrome.

Carpal tunnel: You must have your hand folded down sometimes during sleep. If you hold that position for long enough, carpal tunnel syndrome symptoms can result. Wear a wrist brace specifically designed for carpal tunnel when you go to sleep. Be sure it has a firm support like plastic of metal to keep the wrist in good position. Don't get a completely soft wrist brace since that's not adequate.