The main reason for back pain when sleeping flat on the back at night is related to sleeping position and duration. If the sleep duration is too long, it will lead to extended stress on the lumbar spine, affecting the blood circulation in the lumbar spine, thereby causing back pain. Frequent occurrences of back pain when sleeping flat on the back at night may indicate the presence of lumbar spine diseases or shoulder periarthritis, and CT scans can be used for diagnosis. In addition, it is recommended to avoid sleeping on hard beds as much as possible. Here are some specific causes and recommendations:

1. Muscle spasms

Muscle spasms caused by maintaining the same position for a long time require rest, avoidance of fatigue, trauma, and cold exposure. It is important to maintain correct body posture, avoid staying in the same position for extended periods, sleep on a hard bed, avoid using too high or too soft pillows, and take anti-inflammatory and analgesic medications such as diclofenac sodium. Muscle relaxants such as eperisone hydrochloride can also be used. Local heat therapy and gentle massage can help relieve muscle spasms.

2. Shoulder periarthritis

If this symptom persists for a long time, it may be caused by shoulder periarthritis or ankylosing spondylitis. It is recommended to undergo a CT scan of the neck for diagnosis. Avoid maintaining the same position for extended periods, sleep on a hard bed, and do not use a pillow that is too high. Keep warm, and consider physical therapy, massage, and other methods to relieve pain.

3. Poor blood circulation

Back pain during sleep may be caused by extended periods of lying flat, which compresses the back muscles and impairs blood circulation. If the bed is too soft, it may further exacerbate this issue by overstretching the local muscles. If the pain is relieved by getting up and moving around, it is likely due to extended periods of lying flat or sleeping on a too-soft bed.