The numbness of the left hand at night is generally caused by poor sleeping posture, due to a certain posture during sleep for a long time on the upper limb nerve pressure, resulting in postural abnormalities of sensation, this numbness will disappear after changing the position. If the symptoms of hand numbness do not disappear, it is necessary to consider whether it is caused by disease. 1, cervical disc herniation: mainly due to cervical compression of nerves, generally manifested as pain and numbness of the fingertips, aggravated at night, the need to do cervical CT examination, electromyography examination of the left upper limb, according to the results of the examination using drug therapy; 2, carpal tunnel syndrome: caused by compression of the median nerve, common in some need It is common in middle-aged people who need to do repeatedly hard stretching exercises at the wrist, manifesting as numbness and tingling sensation of the skin on the palm side of the thumb, index and middle finger. Patients with mild symptoms and short duration of disease can consider conservative treatment, such as local closure, local physiotherapy, etc. If conservative treatment is not effective, surgical treatment is needed to reduce nerve compression and relieve the symptoms of numbness; 3. Transient ischemic attack: brain dysfunction caused by temporary cerebral ischemia, manifested as transient blackness before the eyes, hemiparesis, aphasia, and numbness of the partial body. Usually it can be recovered within a short period of time, but if it does not ease for a long time, you need to go to the hospital immediately for treatment to prevent the occurrence of cerebral infarction; 4. Diabetic peripheral neuropathy: It is a relatively common chronic complication, which is caused by nerve and tissue damage due to long-term elevation of blood sugar, manifested in the hands, which can appear as tingling and numbness in the fingers and hands. Blood glucose control is needed before medication is administered. If the symptoms of hand numbness occur while persistently not relieved, you should seek medical attention to clarify the cause and treat it.