The numbness of the thumb at noon in bed may be a normal physiological phenomenon, or it may be caused by diseases, such as cervical spondylosis, carpal tunnel syndrome and so on. 1. Physiological phenomenon: If you sleep pressure to the arm and hand parts, it will lead to local ischemia, causing numbness of the thumb, a normal physiological phenomenon, generally can be relieved on their own. 2. Cervical spondylosis: degenerative cervical spondylosis or long-term strain injury, ligament thickening, etc. will compress the spinal nerve root, resulting in nerve root cervical spondylosis or spinal cord type cervical spondylosis, upper extremity numbness or radiating numbness, inflexibility of the hands, weakness of the hands, and inability to do fine movements and other symptoms. 3. Elbow canal syndrome: the ulnar nerve in the elbow canal is compressed or stretched, causing muscle atrophy and weakness of the hand and numbness and pain on the ulnar side as the main manifestation of the progressive damage of the ulnar nerve. If the elbow is flexed during the nap, it can aggravate the ulnar nerve compression, thus appearing the symptoms of numbness of the little thumb. Many reasons can lead to numbness of the little finger at noon sleep, should go to the hospital in time, according to the clinical symptoms and examination results of comprehensive diagnosis, and treatment.