What causes “growing pains”?

“Growing pains” usually refers to the aches and pains that children feel in their legs at night when they are lying in bed. Kids seem to get them during growth spurts, times when they are growing a lot. Doctors think that the tendons—the tough elastic straps, or bands, that attach muscles to bones—of affected children do not grow quite as fast as their bones do. The tendons eventually catch up, but in the meantime this condition puts muscles under extra stress during an active day and causes them to ache and even spasm (contract abnormally) when they are finally at rest at night. Growing pains are not dangerous. They don’t bother children during the day, and they usually come and go at nighttime. Regular stretching exercises—keeping the muscles and tendons relaxed—often solve the problem for good. But if the pains are very bad and continue for a long time, a doctor should be seen. In rare cases, an infection, disease, injury, or unnoticed malformation of the legs is causing the problem.