There are many reasons for the numbness of the right lateral thigh while sleeping, which may be caused by physiological factors such as physical compression, or pathologic factors such as lumbar spine lesions and lateral femoral dermatitis. 1. Physiological factors: sleeping on the right side of the bed for a long time to maintain the posture, can lead to the right lateral thigh for a long time by the pressure, blood circulation is not smooth, the phenomenon of sleeping on the right lateral thigh numbness, usually in the change of position, after sufficient rest to relieve themselves. 2. Lumbar spine lesions: lumbar disc herniation, lumbar spondylolisthesis, lumbar spinal stenosis, etc., due to the lesions leading to nerve root compression, the phenomenon of numbness of the right lateral thigh can occur, and will be accompanied by the phenomenon of pain in the lower limbs. 3. Lateral femoral dermal neuritis: many causes lead to lateral thigh nerve injury, causing lateral femoral dermal neuritis, numbness of the skin of the lateral thigh, which may also be accompanied by pain and burning sensation. There are many reasons for the numbness of the right lateral thigh when sleeping, if we exclude physiological factors, we suggest that the patient go to the hospital in time to improve the examination and give standardized treatment after a clear diagnosis.