Waking up in the morning with back pain that does not hurt during the day may be caused by the following reasons: 1. There may be rheumatic-type diseases, such as in rheumatoid rheumatoid arthritis attacks, which may invade the small joints of the spine. Once these diseases strike, they often manifest as the phenomenon of morning stiffness. This is when the joints are very stiff and painful in the morning, but after a period of activity, there will be significant relief, and then the cycle repeats. 2, there may be a very mild degree of back soft tissue lesions, such as a very mild degree of muscle spasm or fasciitis in the back, the symptoms are more obvious at night, but after a period of activity during the day, there may be a significant improvement in symptoms. 3, there may be the effect of old injuries, such as old fractures or soft tissue injuries around the spine. These injuries may cause pain during sleep at night or when the weather changes, while the pain may not be so obvious during the day when there is more activity. 4. It may also be caused by osteoporosis, and patients with severe osteoporosis often feel significant pain at night and have similar pain in the morning, which is reduced during the day.