Waking up with a sore back may be caused by kidney deficiency, or it may also be caused by improper sleeping position, overwork, etc. There are more reasons for waking up with a sore back, so it is recommended to consult a doctor. 1. Physiological factors: Maintaining a position for a long time while sleeping, or sleeping on a hard bed, or being overworked, etc., may cause back pain after waking up. 2. Kidney deficiency: Kidney deficiency causes back pain after waking up, which may be accompanied by symptoms of premature aging, forgetfulness, fatigue, reduced sexual function, poor mood and other discomforts. If the symptoms of soreness after waking up are not relieved for a long time or accompanied by other discomforts, it is recommended to consult a doctor in time to identify the causes and carry out targeted treatment.