/b/sixpacksmackdown/posts/muscles-grow-at-rest-signs-you-could-have-a-sleep-disorder-that-is-affecting-your-gains-in-the-gym Proper rest and recovery is vital to growing bigger muscles. Outlined below are the four principles of proper rest and recovery. Rest. Muscles grow when you rest, not when you workout. Sleep. Growth hormone is released when you sleep which builds muen-USTelligent Community 11 Non-Production