Gram Research analysis shows that eating sugary foods after 6 PM significantly reduces sleep quality in professional athletes. A 2026 study of 28 rugby league players found that every gram of sugar consumed in the evening decreased sleep efficiency by 0.21%, meaning athletes who eat sugary snacks late may wake up more during the night and get less restorative sleep. This timing-based finding suggests athletes should avoid sugar-heavy foods and drinks in the evening to improve recovery.
A new study of 28 professional rugby league players found that eating sugary foods after 6 PM significantly disrupted their sleep quality. Researchers tracked what the athletes ate and drank for a full week, then compared it to their sleep patterns measured by special wristbands and sleep diaries. The key discovery: for every gram of sugar consumed in the evening, sleep efficiency dropped by about 0.21%. This research suggests that when elite athletes eat matters just as much as what they eat, especially when it comes to getting good rest for recovery and performance.
Key Statistics
According to research reviewed by Gram, a 2026 study of 28 professional male rugby league athletes found that every 1 gram of sugar consumed after 6 PM was associated with a 0.21% decrease in sleep efficiency, a measure of how much time spent in bed is actually spent sleeping.
A 2026 analysis of 7-day dietary and sleep tracking in 28 elite rugby players showed that evening sugar intake (≥6 PM) had a statistically significant negative relationship with sleep efficiency, while other macronutrients and micronutrients showed no significant associations with sleep quality.
Research published in the International Journal of Sports Physiology and Performance found that when adjusted for body weight, every 1 gram per kilogram of sugar consumed after 6 PM by rugby league athletes resulted in a 0.22% reduction in sleep efficiency.
The Quick Take
- What they studied: How the food and drinks athletes consume, especially in the evening, affects how well they sleep at night.
- Who participated: Twenty-eight professional male rugby league athletes during their preseason training period. Researchers monitored their eating and sleeping habits for 7 consecutive days.
- Key finding: Eating sugary foods after 6 PM was linked to worse sleep efficiency. For every gram of sugar eaten in the evening, sleep quality dropped by about 0.21%, and when measured per kilogram of body weight, it dropped by 0.22%.
- What it means for you: If you’re an athlete trying to improve your sleep and recovery, avoiding sugary snacks and drinks after 6 PM might help you sleep better. However, this study only looked at professional rugby players, so results may differ for other people or sports.
The Research Details
Researchers followed 28 professional rugby league athletes for one full week during their preseason training. Each day, the athletes recorded everything they ate and drank using a smartphone app called MealLogger. At the same time, researchers measured their sleep using two methods: special wristbands called actigraphy devices that track movement during sleep, and sleep diaries where athletes wrote down their own sleep experiences.
The researchers then looked at the data in a special way. They compared what each athlete ate on a specific day with how well they slept that night. They paid special attention to anything eaten or drunk after 6 PM, since evening eating might affect sleep differently than daytime eating. They used a statistical method called linear mixed models to find connections between what athletes ate and how they slept.
This approach allowed researchers to see day-to-day patterns, for example, whether eating more sugar on Tuesday night meant worse sleep Tuesday night, rather than just comparing athletes to each other.
Understanding the timing and type of food athletes eat is crucial because sleep is when the body recovers from training and builds muscle. If certain foods hurt sleep quality, coaches and nutritionists can give better advice about when to eat. This study’s focus on evening eating is important because many athletes snack late, and the timing of food might matter more than we thought.
This study has both strengths and limitations. Strengths include that researchers measured sleep with objective devices (actigraphy) rather than just asking athletes, and they tracked real eating patterns using an app rather than relying on memory. The study also looked at day-to-day relationships, which is more precise than comparing groups. However, the sample size of 28 athletes is relatively small, and all participants were male rugby players, so results may not apply to other groups. The study was also short (only 7 days), so longer-term patterns weren’t examined.
What the Results Show
The main finding was clear: evening sugar intake was linked to reduced sleep efficiency. For every 1 gram of sugar consumed after 6 PM, sleep efficiency decreased by 0.21%. When researchers adjusted this for body weight (a more precise measure), the effect was 0.22% decrease per gram per kilogram of body weight. This means that a 100-kilogram athlete eating an extra 50 grams of sugar after 6 PM could see a noticeable drop in sleep quality.
Sleep efficiency is an important measure, it’s the percentage of time you’re actually asleep versus lying awake in bed. For athletes, even small drops in sleep efficiency can affect recovery and performance. The researchers found this relationship was statistically significant, meaning it’s unlikely to have happened by chance.
Interestingly, the study found no significant relationships between other nutrients and sleep. Total daily energy intake, protein, fat, carbohydrates, and various vitamins and minerals didn’t show strong connections to sleep quality. This suggests that sugar specifically, and particularly sugar consumed in the evening, is the dietary factor most strongly linked to sleep problems in these athletes.
The study measured four different aspects of sleep: total sleep time (how many minutes athletes slept), sleep efficiency (percentage of time actually asleep), wake after sleep onset (how many minutes they were awake during the night), and sleep onset latency (how long it took to fall asleep). Only sleep efficiency showed a significant relationship with evening sugar intake. The other sleep measures didn’t show clear patterns with any dietary factors measured, suggesting that sugar’s main effect is on how restful the sleep is, rather than how long athletes sleep or how quickly they fall asleep.
This research adds important detail to what we already know about nutrition and sleep. Previous studies in general populations have suggested that heavy meals and certain foods can disrupt sleep, but this is one of the first studies to look specifically at elite athletes and to focus on the timing of sugar intake. The finding that sugar specifically matters more than other nutrients is somewhat new and suggests that athletes may need different dietary guidance than the general public. The emphasis on the 6 PM cutoff is practical and aligns with when most athletes would eat their final meal before bed.
Several limitations should be considered. First, this study only included 28 male rugby league athletes, so results may not apply to female athletes, other sports, or non-athletes. Second, the study lasted only 7 days, which is a short time to establish patterns, a longer study might show different results. Third, the study couldn’t prove that sugar causes poor sleep, only that they’re connected; other factors not measured might explain the relationship. Fourth, the study didn’t measure caffeine intake, which is known to affect sleep and might be in sugary drinks. Finally, individual differences weren’t explored, some athletes might be more sensitive to evening sugar than others.
The Bottom Line
Based on this research, professional athletes should consider limiting sugary foods and drinks after 6 PM to improve sleep quality. This recommendation has moderate confidence because the study was well-designed but limited to one group. Athletes should experiment to see if reducing evening sugar helps their individual sleep. This isn’t a strict rule but rather a practical strategy worth trying, especially for athletes struggling with sleep quality.
This finding is most relevant for professional and elite athletes who prioritize recovery and performance, particularly those in rugby and similar sports. Coaches and sports nutritionists should consider this when planning athlete meal timing. The findings may also apply to serious amateur athletes. However, the study doesn’t provide strong evidence for non-athletes or casual exercisers, and individual responses to evening sugar vary.
Athletes might notice improvements in sleep quality within a few days to a week of reducing evening sugar intake, though some people may take longer to see changes. Since the study only tracked 7 days, we don’t know if benefits continue long-term or if the body adapts over time. Athletes should track their sleep for at least 1-2 weeks after making dietary changes to see if they notice a difference.
Frequently Asked Questions
Does eating sugar at night really affect how well athletes sleep?
Yes, according to a 2026 study of 28 professional rugby players, every gram of sugar eaten after 6 PM decreased sleep efficiency by 0.21%. This means athletes who consume sugary foods or drinks in the evening may wake up more during the night and experience less restorative sleep.
What time should athletes stop eating sugary foods to sleep better?
This study found that sugar consumed after 6 PM negatively affected sleep quality. Athletes should aim to avoid sugary foods and drinks after 6 PM, though individual responses vary. Experimenting with a 5-6 PM cutoff for 1-2 weeks can help determine what works best for your sleep.
Does this mean all evening eating is bad for athlete sleep?
No, this study only found problems with sugar specifically. Other nutrients like protein, fat, and carbohydrates showed no significant relationship with sleep quality. Athletes can eat balanced evening meals; they just should avoid sugary snacks and drinks after 6 PM.
How much does evening sugar actually hurt sleep quality?
The effect is measurable but modest. A 100-kilogram athlete eating 50 grams of sugar after 6 PM might see roughly a 1% decrease in sleep efficiency. While this seems small, for elite athletes where every percentage point of recovery matters, it could be meaningful.
Will avoiding evening sugar help non-athletes sleep better too?
This study only tested professional rugby players, so we can’t be certain the results apply to everyone. However, the finding is worth trying for anyone struggling with sleep quality. Individual responses to evening sugar vary, so track your own sleep to see if reducing evening sugar helps you personally.
Want to Apply This Research?
- Log all sugar intake after 6 PM daily, including obvious sources (candy, soda, desserts) and hidden sources (flavored yogurt, granola, sports drinks). Rate sleep quality each morning on a 1-10 scale. After 2 weeks, compare average sleep ratings on high-sugar versus low-sugar evenings.
- Set a personal rule: no sugary foods or drinks after 6 PM on training days. Replace evening snacks with protein-based options (Greek yogurt, nuts, cheese) or complex carbs (whole grain toast). Use the app to plan evening meals and snacks in advance to avoid impulsive sugary choices.
- Track evening sugar intake and sleep quality together in the app for at least 4 weeks. Create a custom report showing the correlation between sugar consumption and next-morning sleep ratings. Adjust the evening sugar cutoff time if needed (try 5 PM or 7 PM) to find your personal optimal timing. Share data with a coach or nutritionist for personalized recommendations.
This research describes associations between evening sugar intake and sleep efficiency in professional male rugby league athletes and should not be interpreted as medical advice. Individual responses to dietary changes vary significantly. Athletes with sleep disorders, dietary restrictions, or medical conditions should consult with a healthcare provider or registered sports dietitian before making significant dietary changes. This study was conducted over only 7 days in a specific athletic population; results may not apply to all individuals or groups. Always work with qualified professionals when making changes to your nutrition or training regimen.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.
