To maximize your gains you need a steady supply of amino acids and small peptides all night that your body can use to repair and build your muscles. The best source of proteins  for sleep is from foods that digest slowly like red meat or chicken because fast releasing proteins (like WPI) only stay in your system for a few hours. But there is a catch. If you eat a big meal that’s hard to digest before bed, it can disrupt your stage 3 & 4 sleep cycles which can inhibit muscle growth.