By 
You’ve probably heard about the importance of protein in helping you build and maintain muscle. It’s the macronutrient that’s most important to have after a weightlifting workout, when you’re looking to make gains in both strength and muscle size. That’s why many people turn to protein shakes and supplements to meet their daily quotas. But when should you have that protein? Some studies point to the specific advantages of having a protein shake before bed.
In fact, one systematic review published in Journal of Science and Medicine in Sport in 2020 found that consuming 20 to 40 grams of casein protein about 30 minutes before you head to bed stimulates protein synthesis as you sleep, and this held true whether participants did resistance training before or not. The catch: This review only involved research on men, with benefits serving mostly healthy young men, and researchers do note that more studies are needed to confirm these benefits.
However, other research points to similar pay-offs of pre-sleep protein. A scientific review, published in the journal Frontiers in Nutrition in 2019, looked at 45 previous studies to see how to best ensure muscle growth and muscle maintenance. The researchers set out to answer: Would simply boosting your daily protein intake be enough to show benefits—or might you see even greater results if you timed it a certain way?
More From Bicycling
The researchers found that people who drank a casein shake with about 30 grams of protein right before bed on days they lifted and on days they rested for 12 weeks gained more muscle mass—about four pounds—and strength than those who drank a non-protein placebo.
While this all sounds promising, there are a few things to keep in mind before making a protein shake before bed part of your regular practice.
The Importance of Protein Throughout the Day
If you want to ride faster and longer, you need muscle. And building muscle requires strength training and rest, as well as consuming enough protein—that can include having a protein shake before bed, but you also want to eat protein in increments throughout the day.
Science has determined a dietary reference intake for both men and women when it comes to protein. Adults assigned female at birth require 46 grams per day while those assigned male require about 56 grams per day. Athletes typically need more, though, up to 1.2 grams per pound bodyweight to maintain or build muscle.
As for how to eat the macronutrient throughout the day, most experts suggest having 25 to 30 grams after a workout to help with recovery. This may be after an evening workout and before bed—in which you’ll get that protein synthesis to kick in while you sleep—but if you work out in the morning, you still want some protein soon after.
“Dietary protein consists of individual amino acids, which are the building blocks of skeletal muscle tissue,” Tim Snijders, Ph.D., lead author of the 2019 Frontiers in Nutrition study and assistant professor at Maastricht University, tells Bicycling. Plus, he adds, resistance exercise increases muscle protein synthesis, or the rebuilding of muscle tissue. Together, the two create an important one-two punch for muscle growth.
So if you want to eat protein throughout the day, especially after workouts, why is it so important to consume protein right before going to sleep? According to Snijders, food isn’t usually ingested during the night when you’re asleep, making this period of time the longest your body goes without eating each day. Because of this, no protein goes to your muscles and no protein synthesis occurs.
By consuming casein, however—which Snijders says is more slowly digested and absorbed compared to whey—your muscles are getting extra fuel to grow.
What to Know Before Having a Protein Shake Before Bed
If you’re worried about drinking protein before bed and gaining weight or ruining your sleep—don’t fret. “All protein that is ingested prior to sleep is used for protein synthesis,” Snijders says. “When exercise is performed earlier that evening, a large part of ingested protein is directed to muscle protein synthesis and is not stored.”
In fact, Snijders adds, he and his researchers didn’t observe any gains in fat mass when young adults consumed protein before bed. Likewise, no studies they reviewed found that participants had trouble falling or staying asleep when consuming casein before bed.
It’s important to note, though, that Snijders and his colleagues aren’t sure if other protein sources beyond casein have the same effect. So, more research is needed.
The Bottom Line on Having a Protein Shake Before Bed
Drinking a casein protein shake right before you go to sleep may boost your muscle growth, which can then pay off in you getting stronger and faster in the saddle. However, if you find that a protein-packed beverage before you hit the sheets leads to disturbed sleep, or it just doesn’t settle well, know that you’ll still benefit from having protein throughout the day.
