A new study of nearly 400 active adults found that drinking coffee doesn’t actually harm sleep quality like many people think. Instead, researchers discovered that stress is the real culprit behind poor sleep. Interestingly, people who drank moderate amounts of coffee and ate mostly plant-based foods reported feeling happier and healthier overall. The study suggests that if you’re an active person worried about your coffee habit affecting your sleep, you might be focusing on the wrong problem—managing stress could be much more important for getting better rest.

The Quick Take

  • What they studied: How coffee drinking and plant-based eating affect sleep quality and mood in people who exercise regularly, and whether stress plays a role
  • Who participated: 392 physically active adults who filled out online surveys about their sleep, diet, coffee habits, stress levels, and emotional well-being
  • Key finding: Stress was strongly linked to poor sleep, but coffee consumption by itself had no negative effect on sleep. People drinking moderate coffee amounts actually reported better mood and health scores
  • What it means for you: If you exercise regularly and worry that your morning coffee is ruining your sleep, you probably don’t need to cut back. Instead, focus on managing stress through exercise, relaxation, or other stress-relief methods. However, this study shows a connection, not proof of cause-and-effect, so individual responses to coffee vary

The Research Details

Researchers asked 392 active adults to complete a detailed survey about their sleep quality, coffee consumption, diet type, stress levels, and emotional well-being. The survey was available online and through QR codes at sports facilities, making it easy for active people to participate. The researchers then used statistical tools to look for patterns—grouping people with similar habits and responses together to see what factors most strongly connected to good or poor sleep. This type of study is called ‘cross-sectional’ because it captures a snapshot of people at one point in time, rather than following them over months or years.

This approach works well for identifying patterns and connections in real-world populations. By studying physically active people specifically, the researchers could see how exercise, diet, and coffee interact in a group that’s already making health-conscious choices. The use of clustering analysis (grouping similar people together) helped reveal which combinations of habits were most strongly linked to better sleep and mood.

The study included a solid sample size of 392 people, which is reasonably large for this type of research. However, because this is a snapshot study rather than a long-term experiment, we can only see that certain habits are connected—not that one thing definitely causes another. The study relied on people’s own reports about their habits and sleep, which can sometimes be less accurate than objective measurements. The findings are most relevant to physically active adults and may not apply equally to less active populations.

What the Results Show

The most striking finding was that stress levels were strongly connected to poor sleep quality—much more so than coffee consumption. People reporting high stress consistently reported worse sleep, while coffee drinkers did not show this same pattern. In fact, people who drank more than two cups of coffee daily often fell into groups reporting better health scores and emotional well-being. The researchers identified four main factors affecting sleep and mood: stress, health, relaxation, and emotional well-being. Stress emerged as the strongest predictor of sleep problems. The healthiest group of participants (those with the best sleep and mood) tended to eat mostly plant-based foods, reported lower stress, and drank moderate amounts of coffee.

Plant-based diets showed a significant positive connection with overall health scores and lower stress levels. Participants who followed more plant-rich eating patterns consistently reported better emotional well-being. The clustering analysis revealed that the combination of moderate coffee intake, plant-based eating, and good stress management created the best outcomes for sleep quality and mood. Physical activity itself appeared to be part of this positive pattern, though the study didn’t isolate its specific effects.

This finding challenges the common belief that coffee is bad for sleep. Previous research has been mixed on this topic, with some studies suggesting coffee disrupts sleep while others found minimal effects. This study adds to growing evidence that moderate coffee consumption may not be the sleep-disruptor many assume. The strong connection between stress and sleep aligns with extensive previous research showing stress as a major sleep disruptor. The positive findings about plant-based diets match earlier studies linking plant-rich eating to better health outcomes.

This study shows connections between habits and sleep quality, but cannot prove that one thing causes another—for example, we can’t say coffee definitely improves mood, only that coffee drinkers in this study reported better mood. The study relied entirely on people’s own reports about their habits and sleep quality, which can be less accurate than objective measurements like sleep trackers or stress tests. The participants were all physically active, so results may not apply to less active people. The study was conducted at one point in time, so we don’t know if these patterns hold up over months or years. Individual responses to coffee vary greatly, so what’s true for the group may not be true for every person.

The Bottom Line

If you’re physically active and concerned about coffee affecting your sleep, the evidence suggests moderate coffee consumption (up to 2+ cups daily) is unlikely to be your problem. Instead, focus on stress management through exercise, relaxation techniques, meditation, or other methods that work for you. Consider incorporating more plant-based foods into your diet, which may support better sleep and mood. These recommendations have moderate confidence because the study shows connections but not definitive cause-and-effect relationships.

This research is most relevant to physically active adults who drink coffee and worry about its sleep effects. It’s particularly useful for athletes, gym-goers, and fitness enthusiasts. People with anxiety or high stress levels should especially focus on stress management rather than blaming coffee. However, if you’re sensitive to caffeine or have sleep disorders, individual responses vary—you may still need to limit coffee. Pregnant women, people with certain health conditions, and those taking specific medications should consult their doctor about coffee consumption regardless of this study.

If you reduce stress through the methods mentioned, you might notice better sleep within 1-2 weeks, though significant improvements often take 4-8 weeks of consistent practice. Changes from adding more plant-based foods may take 2-4 weeks to show effects on mood and energy. Don’t expect overnight changes—sleep quality improvements typically develop gradually as stress management becomes a habit.

Want to Apply This Research?

  • Track daily stress levels (1-10 scale) and sleep quality (hours slept + quality rating) for 4 weeks. Note coffee consumption (cups per day) and percentage of meals that are plant-based. Look for patterns between stress levels and sleep quality rather than focusing on coffee as the variable.
  • Start a daily 10-minute stress-reduction practice (meditation, deep breathing, or gentle stretching) and track how it affects your sleep over 2-4 weeks. Simultaneously, try adding one plant-based meal per day and monitor your mood and energy levels. Keep your normal coffee routine to see if stress management alone improves sleep.
  • Create a weekly dashboard showing: average daily stress score, average sleep hours, sleep quality rating, coffee cups consumed, and plant-based meal percentage. Review weekly trends rather than daily fluctuations. After 4 weeks, compare your stress and sleep patterns to identify your personal sleep triggers—which may differ from the study group.

This study shows associations between habits and sleep quality but does not prove cause-and-effect relationships. Individual responses to coffee vary significantly based on genetics, sensitivity, timing of consumption, and other factors. If you have sleep disorders, anxiety, or are taking medications, consult your healthcare provider before making changes to your coffee consumption or diet. This research applies specifically to physically active adults and may not reflect outcomes for other populations. Always discuss major dietary or lifestyle changes with a qualified healthcare professional, especially if you have underlying health conditions.