Casein protein powder is a complete protein and like whey, is made from milk. This makes casein an effective supplement to increase your protein intake. However, casein is unique among all proteins in that it is digested very slowly. Its micellar structure is disturbed by the acid in your stomach and this causes the casein to form a gelatinous structure which slows the digestion process. This means that rather than flooding your body with essential amino acids, it forms a steady flow of amino acids over up to 7 hours. This makes casein ideal for its anti-catabolic effect while sleeping. The use of casein before sleep maintains muscle mass and reduces muscle breakdown during your sleep.