There are many reasons for the symptoms of hard hand in sleeping, such as tenosynovitis, synovitis, phlebitis of the hand and rheumatoid arthritis and other factors. 1. Tenosynovitis: Long-term use of the fingers for repeated manipulative activities will lead to repeated friction between the tendons and tendon sheaths, causing the tendon sheaths and the surrounding tissues to proliferate and thicken, so that the tendon sheath tissues become jammed, resulting in stiffness of the joints in the fingers during sleep. 2. Synovitis: Long-term exercise or incorrect posture will lead to synovial tissue edema, hyperplasia and other inflammatory reactions, which will cause limited hand movement and stiffness during sleep. 3. Phlebitis of the hand: Inflammation of the blood vessels of the fingers and joints of the hand will affect the blood circulation of the periphery, leading to the symptoms of stiffness of the hand during sleep. 4. Rheumatoid arthritis: Rheumatoid arthritis can lead to symptoms of joint stiffness and limited movement of small joints. The phenomenon of stiff hands while sleeping can occur. There are many factors that cause stiff hands while sleeping, if the stiffness is obvious, it is recommended to go to the hospital in time for consultation and treatment.