If you're eating more protein overall, it might be that—not your bedtime snack—that's helping your muscles grow. So taking protein before bed might not be the real reason for better results.

If you're getting the same amount of protein every day, it doesn't matter whether you drink a shake before bed or at another time — you'll gain the same amount of muscle and strength.

If young guys who work out lift weights and drink a protein shake with about 30 grams of protein before bed for 3 months, they might gain more muscle and get stronger than those who don’t — especially if they’re already eating enough protein during the day.

Eating 20 to 40 grams of protein before bed might help your muscles repair and grow overnight, especially if you also worked out in the evening.

If young, healthy guys lift weights for 12 weeks and drink a protein shake before bed, they might gain more leg muscle than those who don’t — about the size of a small egg more.

We're not sure if eating protein before bed helps older people build stronger muscles, even though it might help their bodies make more muscle overnight — we just don’t have enough long-term studies to say for sure.