Numbness in the right arm at night is commonly caused by cervical spondylosis and elbow canal syndrome, as follows: 1, cervical spondylosis: including neurogenic cervical spondylosis and mixed cervical spondylosis, which can cause pressure on the nerve roots on the right side, and the nerve roots will become edematous and inflammatory, and the patient will show numbness in the right arm at night, accompanied by weakness of the right upper limb, cervical pain and limited cervical movement. X-rays and MRI will reveal the degree and extent of nerve compression; 2. elbow canal syndrome: it will compress the ulnar nerve, and the patient will also have numbness in the right arm, which will lead to muscle atrophy and muscle weakness in the right arm if it lasts for too long, and electromyography will reveal the location and extent of the lesion. Early diagnosis and treatment can relieve the numbness of the right arm and prevent muscle atrophy and muscle weakness.