Pre-workout supplements can disrupt your sleep, but the real risk depends on what's in your pre-workout and when you take it.
You've probably seen the headlines. A study came out in early March 2026 from the University of Toronto, and it wasn't subtle. People who use pre-workout supplements are more than twice as likely to experience extreme sleep deprivation compared to non-users.
Sleep is when your body repairs muscle, adapts and gets stronger, and resets for the next session. If your pre-workout is costing you recovery, you're working against yourself.
Before you consider tossing your tub, here are some things to think about: was the study design flawed, what ingredient in particular was responsible for the claimed sleep disruption, and what separates a pre-workout that supports your performance from one that quietly wrecks it?
What the University of Toronto pre-workout study actually found
The Canadian study was published in December 2025 in the journal Sleep Epidemiology. They analyzed the sleep habits and supplement use of participants aged 16 to 30 and found that those who used pre-workout supplements were more likely to average 5 hours of sleep or less per night. For adults, regularly getting fewer than 7 hours of sleep per night is linked to poorer health outcomes, while for teens aged 13 to 18, the threshold is fewer than 8 hours per night.
The key number: users were more than 2x more likely to fall below that threshold compared to non-users. That's not a marginal effect. That's a pattern.
What the headlines mostly skipped: the study didn't test a specific pre-workout, a specific ingredient, or a controlled dose. It surveyed self-reported supplement use and self-reported sleep duration. This study doesn't tell you exactly which ingredient, at what dose, in which product, caused the problem of sleep deprivation."
Equally problematic, the study design was flawed. Pre-workout users were classified as anyone using a pre-workout over the past 12 months, hile sleep was measured over the past 2 weeks. So, in other words, if someone used a pre-workout 11 months prior to reporting poor sleep, the pre-workout would have been incorrectly flagged as contributing to the poor sleep.
Sleep was based on a single self-reported item about average nightly hours in the past 2 weeks. There was no objective sleep data, no sleep timing, no sleep quality, and no distinction between weekday and weekend sleep. These are just some of the factors that would normally be considered in a quality study measuring sleep.
All this matters because the findings shouldn't have made a blanket statement that "pre-workout supplements are bad. The findings are misleading based on the poor study design and the fact that they didn't even isolate the ingredient(s) that could have directly impacted sleep.
The real problem isn't pre-workout. It's what's in yours
Here’s what most media coverage of this study missed: poorly designed studies often produce findings that don’t hold up in the real world, and the sports supplement industry is far from uniform.
At one end, you have products with transparent labels, disclosed ingredient doses, and 3rd party independent batch testing. At the other end, you have products with proprietary blends: the label lists the ingredient name but not the actual dose. You don't know if you're taking 100mg of caffeine or 300mg.
The University of Toronto study didn't make this distinction. It grouped all pre-workout users together. But an athlete taking 150mg of caffeine from a clean, third-party tested formula at 2pm is in a completely different situation than someone taking 400mg of caffeine from a proprietary blend at 6pm.
Sleep disruption from stimulants is dose-dependent. The higher the stimulant load, and the later in the day you take it, the more your sleep suffers. That's established caffeine pharmacology. A 2013 review in the "Journal of Clinical Sleep Medicine Reviews" confirmed that caffeine consumed within six hours of bedtime results in meaningful sleep disruption.
The problem is that millions of athletes are using pre-workouts without knowing how much caffeine (or what other stimulants) they're actually consuming. In reality, this study didn't vilify pre-workout supplements as a category, but it did highlight the potential consequences of not knowing how much caffeine or other stimulants are in a product.
The ingredients behind the sleep disruption (and the doses that cause it)
Being specific about what's actually disrupting sleep matters, because vague ingredient fear doesn't help anyone.
Caffeine is the primary culprit. The half-life of caffeine in the body is five to six hours for most adults, meaning that if you take a pre-workout containing 300mg of caffeine at 5pm, you still have roughly 150mg active in your system at 11pm. That's the equivalent of a strong espresso, circulating in your bloodstream, telling your nervous system to stay alert.
For context: In 2021, the International Society of Sports Nutrition released a study on caffeine intake and exercise performance. They concluded that caffeine at a dose of 3-6 mg/kg body mass improved exercise performance. For an 82 kg (180 lbs) adult, that works out to between 246 to 492 mg of caffeine (Reference 1). However, the FDA has stated that 400 mg/day is not generally associated with negative health effects. In other words, keeping caffeine below 400 mg/day is generally speaking a wise strategy.Some exceed that. And when that dose is hidden inside a proprietary blend, you have no way to know what you're dealing with.
Synephrine is a stimulant found in some pre-workouts as a caffeine substitute or complement. It works through adrenergic pathways (similar to epinephrine) and can extend the stimulant effect window, compounding the sleep disruption risk when combined with caffeine.
Yohimbine is another stimulant used in some fat-burning pre-workout blends. It has a longer half-life than caffeine and has been linked to increased anxiety and sleep disturbance at higher doses.
Excessive B vitamins at very high doses (particularly B6 and B12, common in energy products) may contribute to restlessness and vivid dreams in sensitive individuals, though this is a secondary factor compared to stimulant load.
The common thread: these are all manageable at appropriate doses, disclosed on the label, with proper timing. They become problematic when doses are hidden, stacked without transparency, or taken too close to bedtime.
Why poor sleep quietly destroys your training results
This is where the University of Toronto finding really matters for athletes, because extreme sleep deprivation doesn't just make you tired. It directly degrades everything you're training for.
Muscle recovery happens during sleep. The majority of growth hormone release (the hormone most directly associated with muscle repair and synthesis) occurs during deep sleep stages. Consistently cutting sleep short means consistently cutting your recovery window. The workout breaks the muscle down. Sleep builds it back.
A 2011 Stanford University study on basketball players found that extending sleep to 10 hours per night improved sprint speed by 5%, reaction time by 15%, and shooting accuracy by 9%, without any other change to their training. They didn't add sessions or change their diet. They just slept more.
Cognitive function degrades fast under sleep deprivation. Coordination, reaction time, decision-making (all critical for athletic performance) deteriorate significantly after even one night below seven hours. For athletes doing technical sport training, this affects both injury risk and skill development.
Sleep deprivation increases cortisol. Elevated cortisol from chronic poor sleep creates a catabolic hormonal environment: the opposite of what you're trying to achieve in the gym. High cortisol combined with low growth hormone creates a poor environment for the adaptations you're training for.
If you're using pre-workout to push harder in training, but that pre-workout is then robbing you of sleep, you're paying twice. The stimulant-assisted performance gain is at least partially offset by the recovery deficit it creates. 
What a clean, transparent pre-workout label should tell you
Not all pre-workouts carry the same risk. The ones that cause damage share a few common characteristics: hidden doses (proprietary blends), high stimulant stacking, and no independent batch testing. The ones that don't have those problems are built differently.
Here's what to look for on a pre-workout label:
Disclosed caffeine dose. The label should tell you exactly how much caffeine is in a serving (in milligrams, not hidden inside a "performance blend"). If it doesn't, you can't manage your timing properly.
No proprietary blends for stimulant ingredients. "Stimulant complex: 500mg" tells you nothing useful. Individual ingredient doses matter, especially for the ones that affect your nervous system.
Third-party certification. This is the cleanest signal available. Informed Choice certification, operated by LGC Group (the same lab used by the International Olympic Committee for anti-doping testing), means every production batch of a supplement has been independently verified to contain what the label says — and nothing the label doesn't say. You can read more about what Informed Choice certification means for athletes.
PVL's DOMIN8 pre-workout carries Informed Choice certification. Every batch is tested. The caffeine dose is disclosed on the label. You know exactly what you're taking, which means you can time it properly and make an informed decision about your sleep.
That's what the Canadian study implicitly called for: not an end to pre-workout use, but an end to the black-box supplementation culture that made the correlation it found so widespread.
How pre-workout and sleep interact: The six-hour rule
Knowing what's in your pre-workout is the first step. Knowing when to take it is the second.
The six-hour rule for caffeine is the most evidence-based timing guideline available. A 2013 study published in the Journal of Clinical Sleep Medicine found that consuming 400mg of caffeine six hours before bedtime reduced total sleep time by more than one hour. Even at three hours before bed, the effect was measurable. The recommendation: treat your pre-workout timing as part of your sleep hygiene plan, not an afterthought.
Practical timing guidance:
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If you train in the morning (6-10am): pre-workout timing is rarely a problem for sleep
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If you train midday (11am-2pm): most caffeine will be cleared before typical sleep time
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If you train late afternoon (3-5pm): target at least six hours before your intended sleep time
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If you train in the evening (6pm+): consider a stimulant-free or low-stimulant formula, or reduce the dose by half
On rest days: there is no performance reason to take a stimulant pre-workout on a rest day. If you use it for energy, that's a signal worth examining. It may indicate that your baseline energy is being propped up by stimulants, which is a separate issue from training optimization.
Label your sleep as a training variable. Serious athletes track their lifts, their food, their steps. Most don't track sleep. Start treating 7-9 hours of sleep as a non-negotiable training target, in the same category as hitting your protein intake or completing your sessions.
What to do with this
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Check your label for a disclosed caffeine dose. If it says "proprietary blend," you don't know what you're taking. Look for a product with fully disclosed ingredient amounts.
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Apply the six-hour rule. Take your pre-workout at least six hours before your intended sleep time. If you train in the evening, use a low-stimulant or stimulant-free formula on those days.
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Look for Informed Choice certification. This is the cleanest available signal that a product's label is accurate and batch-tested independently.
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Track your sleep like a training variable. Target 7-9 hours per night. If you're consistently below 7, identify whether your pre-workout timing is a contributing factor before adjusting anything else.
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Don't use pre-workout as a fatigue management tool. If you need it to function (not just to train), that's a signal your baseline recovery is insufficient and stimulants aren't the fix.
What it comes down to
The Canadian study isn't a reason to abandon pre-workout. It's a reason to be smarter about which one you use and when you take it.
The athletes getting hurt by this aren't the ones using a clean, transparent formula with a disclosed caffeine dose and proper timing. They're the ones taking undisclosed stimulant loads too late in the day and paying for it every night.
If you want a pre-workout that works hard for your training without working against your recovery, look for one with a transparent label, a certified production process, and a caffeine dose you can actually plan around.
PVL DOMIN8 is Informed Choice Certified, with every batch tested by LGC Group. The caffeine dose is on the label. You know what you're taking and you can time it. That's what responsible pre-workout supplementation looks like.
References
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University of Toronto / Preventive Medicine Reports, March 8, 2026
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Sleep Medicine Reviews, 2023 (caffeine and sleep)
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Mah et al., Stanford University, 2011
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Drake et al., Journal of Clinical Sleep Medicine, 2013
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Watson NF, Badr MS, Belenky G, Bliwise DL, Buxton OM, Buysse D, Dinges DF, Gangwisch J, Grandner MA, Kushida C, Malhotra RK, Martin JL, Patel SR, Quan SF, Tasali E. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. J Clin Sleep Med 2015;11(6):591–592.
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Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013;9(11):1195-1200. Published 2013 Nov 15. doi:10.5664/jcsm.3170
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Guest NS, VanDusseldorp TA, Nelson MT, et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18(1):1. Published 2021 Jan 2. doi:10.1186/s12970-020-00383-4
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Khan MA, Al-Jahdali H. The consequences of sleep deprivation on cognitive performance. Neurosciences (Riyadh). 2023;28(2):91-99. doi:10.17712/nsj.2023.2.20220108
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Wright KP Jr, Drake AL, Frey DJ, et al. Influence of sleep deprivation and circadian misalignment on cortisol, inflammatory markers, and cytokine balance. Brain Behav Immun. 2015;47:24-34. doi:10.1016/j.bbi.2015.01.00
