Casein proteins are slow digesting proteins that are often taken before bed to help with post-workout recovery and to reduce muscle breakdown during sleep. These proteins are known as “time-release” proteins due to the slow absorption rate in the gut. This means that its amino acids are broken down in your body at a low level over a longer period of time. One of the main benefits and use cases of casein is for the reduction of muscle breakdown over night. So if you are really serious bulking up, get yourself some casein protein.