Sleeping at night back pain during the day does not hurt consider physiological factors, pathological factors such as ankylosing spondylitis, lumbar dorsal myofasciitis and other reasons. 1. Physiological factors: the bed is too soft when you sleep at night, lying in bed, the spine is in a state of distortion, the lumbar region is subjected to increased load, which is easy to cause muscle strain, lumbar pain. 2. Ankylosing spondylitis: mostly resting pain, nocturnal pain, back and lumbosacral pain, morning stiffness, relieved after activities. 3. Myofasciitis: myofascia due to strain or trauma occurs aseptic inflammation, localized adhesions, when resting inflammatory factors and lactic acid accumulation of pain, some will have back stiffness. During the day because of more activity, blood circulation improves, pain symptoms reduce and disappear. Sleeping at night back pain during the day without pain etiology has a variety of possibilities, need to go to the hospital to check, clear cause for treatment.