The idea that eating protein before bed—often called “pre-sleep protein”—can help build muscle while you sleep has merit, but just how much do you need to consume to reap benefits? Here’s what experts had to say.
Research suggests about 40 grams of protein should be consumed to stimulate muscle growth throughout the night, said sports nutrition consultant Mandy Tyler, MEd, RD. Several studies have shown that this amount, typically consumed 30 minutes before bed, has muscle-building benefits.
You don’t need to consume an additional 40 grams beyond your usual protein intake. Rather, clinical dietitian Toby Amidor, MS, RD advised making it part of your daily protein target. According to the International Society of Sports Nutrition, adults who exercise should strive for 1.4 to 2.0 grams of protein per kilogram of body weight per day. For a 150-pound person, that’s 95 to 136 grams daily. Forty grams of protein before bed would be 29% to 42% of this range.
Just note that, for some people, eating a large amount of protein before bed could cause GI disruption—and ultimately mess with sleep. “These individuals may need to experiment with the timing and type of protein-rich foods consumed prior to bed,” Tyler said.
If you don’t eat before bed, no new dietary amino acids enter your bloodstream during the overnight fast. But having protein before you turn in provides a steady release of amino acids while you sleep, since digestion continues throughout the night. Those amino acids can stimulate muscle protein synthesis and improve net muscle protein balance—the difference between muscle built and muscle lost.
Still, much depends on the type of protein you consume, Amidor said.
The two types with the most evidence for supporting overnight muscle growth are casein and whey, which are found in dairy products like cottage cheese and milk, and provide all the amino acids your body needs. “Casein and whey both help benefit muscle building, maintenance, and recovery,” Amidor said. “However, each works a bit differently.”
Whey protein—one of the most concentrated sources of leucine, an amino acid responsible for building muscle—digests faster than casein and releases amino acids to the muscles more quickly. Some research suggests that when consumed before sleep, whey protein may help rebuild connective tissue overnight.
Casein, on the other hand, digests more slowly, releasing its amino acids to your muscles more gradually. Despite its slower release, research has shown casein promotes overnight muscle growth. A 2021 study found that consuming 20 to 40 grams before bed stimulated whole-body protein synthesis rates in young and older men.
To reap the most benefits from a pre-sleep protein routine, Amidor recommends consuming a combination of whey protein and casein.
Another key way to maximize bedtime protein benefits is to incorporate strength training into your day, whether early on or in the evening (some research suggests that intense exercise before bed may disrupt sleep, so you may want to keep it gentle). “The combination of strength training and pre-sleep protein appears to further increase muscle growth during the overnight period,” Tyler said.
Strength training means using resistance, such as body weight or free weights, to make you stronger. Examples include squats, push-ups, lunges, and planks.
