Adolescents and young adults who consume pre-workout dietary supplements may be sacrificing essential rest for their fitness goals. A recent analysis indicates that individuals in this age group who use these performance-enhancing products are more likely to report sleeping fewer than five hours per night. These findings were published recently in the journal Sleep Epidemiology.

The pressure to achieve an ideal physique or enhance athletic performance drives many young people toward dietary aids. Pre-workout supplements, often sold as powders or drinks, are designed to deliver an acute boost in energy and endurance. These products have gained popularity in fitness communities and on social media platforms.

Despite their widespread use, the potential side effects of these multi-ingredient formulations are not always clear to consumers. The primary active ingredient in most pre-workout blends is caffeine, often in concentrations far exceeding that of a standard cup of coffee or soda. While caffeine is a known performance enhancer, its stimulant properties can linger in the body for many hours.

Kyle T. Ganson, an assistant professor at the Factor-Inwentash Faculty of Social Work at the University of Toronto, led the investigation into how these products affect sleep. Ganson and his colleagues sought to address a gap in current public health knowledge regarding the specific relationship between these supplements and sleep duration in younger populations.

The researchers drew data from the Canadian Study of Adolescent Health Behaviors. This large-scale survey collects information on the physical, mental, and social well-being of young people across Canada. The team focused on a specific wave of data collected in late 2022.

The analysis included 912 participants ranging in age from 16 to 30 years old. The researchers recruited these individuals through advertisements on popular social media platforms, specifically Instagram and Snapchat. This recruitment method allowed the team to reach a broad demographic of digital natives who are often the target audience for fitness supplement marketing.

Participants answered questions regarding their use of appearance- and performance-enhancing substances over the previous twelve months. They specifically indicated whether they had used pre-workout drinks or powders. Additionally, the survey asked participants to report their average nightly sleep duration over the preceding two weeks.

To ensure the results were robust, the researchers accounted for various factors that might influence sleep independently of supplement use. They adjusted their statistical models for variables such as age, gender, and exercise habits. They also controlled for symptoms of depression and anxiety, as mental health struggles frequently disrupt sleep patterns.

The results showed a clear distinction between users and non-users of these supplements. Approximately 22 percent of the participants reported using pre-workout products in the past year. Those who did were substantially more likely to report very short sleep durations.

Specifically, the study found that pre-workout users were more than 2.5 times as likely to sleep five hours or less per night compared to those who did not use the supplements. This comparison used eight hours of sleep as the healthy baseline. The association remained strong even after the researchers adjusted for the sociodemographic and mental health variables.

The researchers did not find a statistically significant link between pre-workout use and sleeping six or seven hours compared to eight. The strongest signal in the data was specifically for the most severe category of sleep deprivation. This suggests that the supplements may be contributing to extreme sleep deficits rather than minor reductions in rest.

Biology offers a clear explanation for this phenomenon. Caffeine functions by blocking adenosine receptors in the brain. Adenosine is a chemical that accumulates throughout the day and promotes sleepiness; by blocking it, caffeine induces a state of alertness.

This mechanism helps during a workout but becomes a liability when trying to rest. Ganson highlights the dosage as a primary concern.

“These products commonly contain large doses of caffeine, anywhere between 90 to over 350 mg of caffeine, more than a can of Coke, which has roughly 35 mg, and a cup of coffee with about 100 mg,” said Ganson. “Our results suggest that pre-workout use may contribute to inadequate sleep, which is critical for healthy development, mental well-being, and academic functioning.”

Beyond simple wakefulness, caffeine also delays the body’s internal release of melatonin. This hormone signals to the body that it is time to sleep. Disrupting this rhythm can make it difficult to fall asleep at a reasonable hour.

Additionally, high doses of stimulants activate the sympathetic nervous system. This biological response increases heart rate and blood pressure. A body in this heightened state of physiological arousal is ill-equipped for the relaxation necessary for deep sleep.

The timing of consumption plays a major role in these effects. Young adults often exercise in the afternoon or evening after school or work. Consuming a high-stimulant beverage at this time means the caffeine is likely still active in their system when they attempt to go to bed.

This sleep disruption is particularly concerning for the age group studied. Adolescents generally require between 8 and 10 hours of sleep for optimal development. Young adults typically need between 7 and 9 hours.

Chronic sleep deprivation in this developmental window is linked to a host of negative outcomes. These include impaired cognitive function, emotional instability, and compromised physical health. The authors note that the very products used to improve health and fitness might be undermining recovery and overall well-being.

“Pre-workout supplements, which often contain high levels of caffeine and stimulant-like ingredients, have become increasingly popular among teenagers and young adults seeking to improve exercise performance and boost energy,” said Ganson. “However, the study’s findings point to potential risks to the well-being of young people who use these supplements.”

The study does have limitations that readers should consider. The data is cross-sectional, meaning it captures a snapshot in time rather than tracking individuals over years. As a result, the researchers cannot definitively prove that the supplements caused the sleep loss.

It is possible that the relationship works in the opposite direction. Individuals who are chronically tired due to poor sleep habits may turn to pre-workout supplements to power through their exercise routines. This could create a cycle of dependency and fatigue.

Furthermore, the study relied on self-reported data. Participants had to recall their sleep habits and supplement use, which introduces the possibility of memory errors. The survey also did not ask about the specific dosage or timing of the supplement intake.

Despite these limitations, the authors argue the association is strong enough to warrant attention from healthcare providers. They suggest that pediatricians and social workers should ask young patients about their supplement use. Open conversations could help identify potential causes of insomnia or fatigue.

Harm reduction strategies could allow young people to exercise safely without compromising their rest. The most effective approach involves timing. Experts generally recommend avoiding high doses of caffeine 12 to 14 hours before bedtime to ensure the substance is fully metabolized.

“Young people often view pre-workout supplements as harmless fitness products,” Ganson noted. “But these findings underscore the importance of educating them and their families about how these supplements can disrupt sleep and potentially affect overall health.”

Future research will need to examine the nuances of this relationship. Longitudinal studies could track users over time to establish a clearer causal link. Researchers also hope to investigate how specific ingredients beyond caffeine might interact to affect sleep quality.

The study, “Use of pre-workout dietary supplements is associated with lower sleep duration among adolescents and young adults,” was authored by Kyle T. Ganson, Alexander Testa, and Jason M. Nagata.

Most animals, including humans, carry an internal lunar clock, tuned to the 29.5-day rhythm of the Moon. It guides sleep, reproduction and migration of many species. But in the age of artificial light, that ancient signal is fading – washed out by the glow of cities, screens and satellites.

Just as the circadian rhythm keeps time with the 24-hour rotation of the Earth, many organisms also track the slower rhythm of the Moon. Both systems rely on light cues, and a recent study analysing women’s menstrual cycles shows that as the planet brightens from artificial light, the natural contrasts that once structured biological time are being blurred.

Plenty of research suggests the lunar cycle still influences human sleep. A 2021 study found that in Toba (also known as Qom) Indigenous communities in Argentina, people went to bed 30-80 minutes later and slept 20-90 minutes less in the three-to-five nights before the full Moon.

Similar, though weaker, patterns appeared among more than 400 Seattle students in the same study, even amid the city’s heavy light pollution. This suggests that electric light may dampen but not erase this lunar effect.

The researchers found that sleep patterns varied not only with the full-Moon phase but also with the new- and half-Moon phases. This 15-day rhythm may reflect the influence of the Moon’s changing gravitational pull, which peaks twice per lunar month, during both the full and new Moons, when the Sun, Earth and Moon align. Such gravitational cycles could subtly affect biological rhythms alongside light-related cues.

Laboratory studies have supported these findings. In a 2013 experiment, during the full Moon phase participants took about five minutes longer to fall asleep, slept 20 minutes less, and secreted less melatonin (a hormone that helps regulate the sleep-wake cycle). They also showed a 30% reduction in EEG slow-wave brain activity – an indicator of deep sleep.

Their sleep was monitored over several weeks covering a lunar cycle. The participants also reported poorer sleep quality around the full Moon, despite being unaware that their data was being analysed against lunar phases.

Perhaps the most striking evidence of a lunar rhythm in humans comes from the recent study analysing long-term menstrual records of 176 women across Europe and the US.

Before around 2010 – when LED lighting and smartphone use became widespread – many women’s menstrual cycles tended to begin around the full Moon or new Moon phases. Afterwards, that synchrony largely vanished, persisting only in January, when the Moon-Sun-Earth gravitational effects are strongest.

The researchers propose that humans may still have an internal Moon clock, but that its coupling to lunar phases has been weakened by artificial lighting.

A metronome for other species

The Moon acts as a metronome for other species. For example, coral reefs coordinate mass spawning events with precision, releasing eggs and sperm under specific phases of Moonlight.

In a 2016 laboratory study, researchers working with reef-building corals (for example A. millepora) replaced the natural night light cycle with regimes of constant light or constant darkness. They found that the normal cycling of clock-genes (such as the cryptochromes) was flattened or lost, and the release of sperm and eggs fell out of sync. These findings suggest lunar light cues are integral to the genetic and physiological rhythms that underlie synchronised reproduction.

Other species, such as the marine midge Clunio marinus, use an internal “coincidence detector” that integrates circadian and lunar signals to time their reproduction precisely with low tides. Genetic studies have shown this lunar timing is linked to several clock-related genes – suggesting that the influence of lunar cycles extends down to the molecular level.

However, a 2019 study found that the synchrony of wild coral spawning is breaking down. Scientists think this may be due to pollutants and rising sea temperatures as well as light pollution. But we know that light pollution is causing disruption for many wildlife species that use the Moon to navigate or time their movements.

Near-permanent brightness

For most of human history, moonlight was the brightest light of night. Today, it competes with an artificial glow visible from space. According to the World Atlas of Artificial Night Sky Brightness, more than 80% of the global population – and nearly everyone in Europe and the US – live under a light-polluted sky (one that is bright enough to hide the Milky Way).

In some countries such as Singapore or Kuwait, there is literally nowhere without significant light pollution. Constant sky-glow from dense urban lighting keeps the sky so bright that night never becomes truly dark.

This near-permanent brightness is a by-product of these countries’ high population density, extensive outdoor illumination, and the reflection of light off buildings and the atmosphere. Even in remote national parks far from cities, the glow of distant lights can still be detected hundreds of kilometres away.

In cognitive neuroscience, time perception is often described by pacemaker–accumulator models, in which an internal “pacemaker” emits regular pulses that the brain counts to estimate duration. The stability of this system depends on rhythmic environmental cues – daylight, temperature, social routines – that help tune the rate of those pulses.

Losing the slow, monthly cue of moonlight may mean that our internal clocks now run in a flatter temporal landscape, with fewer natural fluctuations to anchor them. Previous psychological research has found disconnection from nature can warp our sense of time.

The lunar clock still ticks within us – faint but measurable. It shapes tides, sleep and the rhythms of countless species. Yet as the night sky brightens, we risk losing not only the stars, but the quiet cadence that once linked life on Earth to the turning of the Moon.

This article is republished from The Conversation under a Creative Commons license. Read the original article.