Plenty of people use pre-workout supplements to boost their training efforts. But new research suggests that regularly using pre-workout could unintentionally counteract your healthy living goals.
The study, which was published in the journal Sleep Epidemiology, found a link between people who use pre-workout regularly and getting significantly lower amounts of sleep each night. You probably already know this, but getting seven-plus hours of sleep each night supports a wide range of health, including boosting your immune system, keeping your mood stable, and reducing your risk of chronic conditions like type 2 diabetes and heart disease. So what do these findings mean if you’re a pre-workout fan and are trying to be as healthy as possible?
Doctors and a dietitian explain the link.
The study doesn’t paint a pretty picture for sleep and pre-workout supplements.
For the study, researchers analyzed data from more than 900 people who participated in a Canadian health study. The participants were asked about their pre-workout use over the past 12 months, along with how many hours of sleep per night they averaged over the previous two weeks.
After crunching the data, the researchers discovered that people who said they used pre-workout were “significantly” more likely to report that they slept an average of five or less hours a night over the past two weeks compared to those who said they didn’t use pre-workout.
“This study documents that the use of pre-workout supplements is associated with lower sleep duration,” the researchers wrote in the study.
Why might pre-workout be bad for sleep?
It’s important to point out that the study didn’t prove that the pre-workout caused people to sleep less. Instead, the researchers found a link between people who said they used pre-workout and got less sleep at night. Still, experts say there are a few things to consider that suggest pre-workout may not be great for your sleep health.
A big one is that pre-workout usually contains caffeine. (There are caffeine-free pre-workout supplements out there, but they’re not as popular as the caffeine-containing ones.) One 2023 study found that pre-workout has an average of 217 milligrams of caffeine per serving, which is equal to what you’d get from having about two cups of coffee. That study suggested that people who use pre-workout have it at least 13.2 hours before bedtime to lower the risk it will mess with sleep.
“Caffeine typically blocks adenosine receptors, which is a neurotransmitter that builds through the day to increase sleep pressure by the evening,” Aarti Grover, MD, medical director of the Center for Sleep Medicine at Tufts Medical Center, tells SELF. “Also, caffeine can delay production of melatonin—typically produced three to four hours before natural bedtime—which can also make it harder to fall asleep at the usual time.”
But 217 milligrams is the average amount of caffeine in pre-workout. “The amount of caffeine in pre-workout can vary wildly—100 milligrams to 400 milligrams—so that amount really matters, particularly if you are also consuming caffeine elsewhere,” W. Christopher Winter, MD, a neurologist and sleep medicine physician with Charlottesville Neurology and Sleep Medicine and host of the Sleep Unplugged podcast, tells SELF.
“Caffeine has a half-life of roughly five to seven hours in most adults, but there’s wide variability based on genetics, habitual intake, and liver metabolism,” Scott Keatley, RD, cofounder of Keatley Medical Nutrition Therapy, tells SELF. So, if someone takes a typical pre-workout dose at 2 p.m., they still may have at least 75 milligrams of caffeine active in their system at 9 p.m., he points out. “That’s enough to reduce sleep latency, fragment sleep, or blunt deep sleep,” Keatley says.
Caitlyn Mooney, MD, assistant professor in the department of sports medicine at Vanderbilt University Medical Center, agrees that caffeine is likely the big issue here. “Caffeine is known to block signals that impact sleep onset, shifts our circadian rhythm, and increases our flight or fight reaction…. This can make it harder to fall asleep, stay asleep, and our sleep will be less restorative,” she tells SELF. “Even if one falls asleep okay, they may have poorer-quality sleep, which may still affect their longer-term performance.”
One more thing on the caffeine front to consider: It’s generally recommended that people have no more than 400 milligrams of caffeine a day. But if you’re not used to having caffeine, you should probably top yourself out at 200 milligrams, Christian Muller, DO, primary care and sports medicine physician at Northwell Health Orthopedics in Westchester, tells SELF. Otherwise, that caffeine load could really mess with your sleep. “It is important to check the amount of caffeine and other stimulants In a pre-workout supplement prior to taking,” Dr. Muller says.
But there could be more to it than caffeine, Dr. Mooney says. “Sleep is also affected by working out close to bedtime or trying to fit in workouts in a busy schedule,” she says. When you combine that with taking a large dose of caffeine in the afternoon or evening, it can be a “double whammy” for sleep health, Dr. Winter says. “Especially given the bright lights in the gym, the increase in body temperature, eating after the workout—all of that is not great for sleep,” he says.
There also could be other ingredients in pre-workout beyond caffeine that act as a stimulant, according to Dr. Mooney. “So it’s important to read labels,” she adds.
It’s a good idea to rethink your pre-workout use, experts say.
You don’t have to take pre-workout, even if you like to get an energy boost before your workout. “For most people, simple, targeted nutrition can replace pre-workout supplements and provide nearly the same benefit,” Keatley says. He suggests having a quick carbohydrate source like a banana or toast with honey to support training intensity, or having oatmeal if you have a little more time to digest before your workout.
“If someone wants a stimulant effect, coffee is easier to dose and usually provides less total caffeine than pre-workout,” Keatley says. “Beyond that, hydration and a bit of sodium, especially for longer or sweat-heavy sessions, matter more for performance than most proprietary blends.”
It’s also important to think about why you’re using pre-workout. “People who use caffeine and pre-workout may already be trying to squeeze workouts into a busy schedule, thus waking early, staying up late, sleeping less, and using pre-workout and caffeine to compensate for fatigue,” Dr. Mooney says. “But the combination may lead to less rest and more fatigue down the line.” (She points out that exercise is stimulating on its own too.)
Dr. Mooney stresses the importance of sleep for recovery and muscle repair. “Less sleep is tied to increased injury risk and reduced performance, including reaction times and endurance,” she says. “Thus, sleep is also an important aspect of fitness and performance.”
If you enjoy using pre-workout and feel like it helps your performance, you don’t need to swear it off entirely. Instead, Dr. Mooney suggests paying close attention to when you use the supplement. “Try to use it only with morning workouts,” she says. “Avoid caffeine supplements in afternoon workouts.” Dr. Winter agrees. “There’s much less sleep disruption from using pre-workout in the morning,” he says.
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