The pain all over the body at night may be caused by the following reasons: First, it is possible that the mattress is too soft or too hard to sleep on, resulting in strain pain when the muscles of the lower back have to be contracted with prolonged force to maintain a normal body position while sleeping. Second, it is possible that after doing strenuous exercise or heavy physical labor during the day, resulting in soreness and pain in the muscles of the whole body. This condition is most commonly caused by the accumulation of lactic acid in the muscles of the whole body, which induces soreness, pain, weakness and other symptoms. Thirdly, it may be caused by viral infection, most commonly upper respiratory tract infection, and the virus invades the muscles and joints of the whole body through blood circulation, resulting in muscle soreness, weakness and pain throughout the body. This condition is usually accompanied by symptoms of upper respiratory tract infection, such as nasal congestion, runny nose, sore throat, dry throat, cough, cough or fever.