Lumbar pain at 4 to 5 a.m. is fine during the day may be caused by lumbar disc herniation, improper sleeping posture, cold, exertion, and so on. 1. Lumbar disc herniation: when sleeping at night because the mattress is too soft, the lumbar support is not comprehensive, the lumbar discomfort, such as pain and soreness, can occur in the early hours of the morning. 2. Improper sleeping posture: the same posture for a long time can lead to lumbar strain and cause pain. 3. Cold: inadequate warmth can lead to cold and wind in the lumbar region, and local meridians are not smooth and can cause pain. 4. Exertion: a lot of exercise or labor during the day, such as lumbar weight-bearing, playing soccer, basketball, etc.. Wait until the evening after sleeping and resting can appear lumbar pain and discomfort. 4-5 am back pain during the day may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.