Is it good to use the massage belt in the morning or at night?

You should be talking about the waistline, that is, the waist with steel plates inside. Waist circumference is usually worn when waist pain is severe, especially during the day and when sleeping at night. However, I suggest that you don't wear it if you have a light back pain. After all, wearing it often can make up for the loss of lumbar muscles. Waist circumference can stabilize and protect the lumbar spine when low back and leg pain is serious.