There are many reasons for the lack of strength in the back and the desire to lie down, such as prolonged exertion and poor posture. It may also be caused by osteoporosis, thoracic spine disease, insufficient blood supply to the brain and other diseases. 1. Prolonged exertion, such as working with a low head, heavy physical activities caused by prolonged tension or strain on the back muscles, can appear back, very tired, always want to lie down, usually need to pay attention to rest, appropriate massage to relax the muscles. 2. Age, easy osteoporosis, activity gradually decline, will cause back pain and weakness, always want to lie down. Can usually increase calcium intake. 3. Thoracic spine diseases such as herniated disc can compress the nerves and cause back pain and weakness. 4. Insufficient blood supply to the brain can also cause dizziness, back weakness and other symptoms. The back is weak and always want to lie down can also be seen in other diseases, if after rest, posture adjustment symptoms did not improve, it is recommended to go to the hospital in a timely manner, clear disease, timely treatment.