Whey Before Bed Halved Time to Fall Asleep. Casein Didn't
Everyone says casein is the bedtime protein, but a new randomized, double-blind crossover trial in humans found something odd. After resistance training, 40 g of whey taken 30 minutes before bed cut median sleep-onset time to 9 minutes versus 19 with a carb control, and also reduced next-day soreness. Casein did not significantly beat control. The catch: only nine people took part, and whey wasn't statistically better than casein head-to-head. Here's what the numbers show and what they can't prove.
Casein Before Bed Won't Wreck Your Sleep, WHOOP Data Shows
Does a 40 g casein shake before bed secretly sabotage your sleep? A randomized, double-blind crossover trial in 21 NCAA Division I female athletes tracked sleep with WHOOP 4.0 bands and found no hit to sleep time, efficiency, resting heart rate or HRV. Alpha-lactalbumin and carbohydrate performed the same. But there's a twist: none of them improved sleep either. Here's what the data show, where the study falls short, and who should still skip the late-night shake.
The 40 g Bedtime Shake: What Pre-Sleep Casein Does Overnight
Lift in the evening, then fast for eight hours: does that hurt recovery? A 2012 study gave 16 young men 40 g of casein 30 minutes before bed and tracked what happened overnight. The protein was digested and absorbed during sleep, whole-body protein synthesis jumped (311 vs 246 µmol/kg), and net protein balance flipped from negative to positive. Muscle protein synthesis was about 22% higher, though only borderline significant. Here is what the findings mean, what they don't, and how to use them.