So you hit the gym hard, but you're just not seeing the gains you expect? It might not be your workout that's failing you. It could actually be your sleep: Despite what you've heard from all the meatheads at the gym, you can't just pound weights all day and then expect to subsist on three hours of Red-Bull-interrupted sleep every night.

But let's say you do get eight hours of sleep a night, and you're still not making as much progress as you'd expect.

The solution? “Lift weights at least three hours before bed and take casein—a slow-digesting protein powder—before bed,” says Jorn Trommelen, owner of nutritiontactics.com.

“Research shows that when resistance exercise is performed earlier in the day, more of the pre-sleep protein ends up in muscle and is used to form new muscle proteins,” he says. The synergy between resistance exercise and protein lasts for at least 24 hours after exercise.