Probiotics for sleep in athletes: what the evidence says
Summary
What is it? A look at whether probiotics (live bacteria taken as a supplement) and synbiotics (probiotics combined with a prebiotic, a substance that feeds them) improve sleep in athletes and other trained people. The main source is a 2026 systematic review of six randomised trials [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026. A systematic review uses a set, repeatable search to find every trial on a question.
Why would I need it? Hard training, travel and competition often disturb athletes' sleep. Some researchers think gut bacteria may affect sleep, so probiotics have been tested as a simple way to help [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
Is it useful? Possibly, for how well people feel they slept, but the evidence is weak. In the review, 9 of 12 sleep outcomes favoured the supplement and none favoured placebo. However, the trials were small, all six had some risk of bias, and two of the nine positive results do not hold up on a closer look [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026[2]Probiotic supplementation elicits favourable changes in muscle soreness and sleep quality in rugby players. Harnett JE, Pyne DB, McKune AJ, et al. J Sci Med Sport, 2021[3]Evaluating the Impact of Probiotic Therapy on the Endocannabinoid System, Pain, Sleep and Fatigue: A Randomized, Double-Blind, Placebo-Controlled Trial in Dancers. Wiącek J, Podgórski T, Kusy K, et al. Int J Mol Sci, 2024. The authors themselves call the evidence limited and ask for larger trials [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
FAQ
Do probiotics improve sleep in athletes? They may. The review found that 9 of 12 sleep outcomes favoured probiotics or synbiotics, 3 showed no effect, and none favoured placebo. The clearest effect was on self-rated sleep quality [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026. This is only a rough tally: it mixes different kinds of outcome and says nothing about how large the effect is [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
Do they help athletes fall asleep faster? It is unclear. The dancer trial found no change in sleep latency, the time it takes to fall asleep. A synbiotic trial in soccer players (13 athletes, by the review's count) found a significant improvement [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
Did the trials measure sleep with devices? Mostly not. Most results came from questionnaires. One trial used a movement sensor (actigraphy), and one used a headband that records brain waves. None used polysomnography, the full overnight sleep test done in a laboratory [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
Can I trust the "9 of 12" figure? Only in part. In the dancer trial, the better sleep quality was a trend that did not reach significance (p = 0.078) [3]Evaluating the Impact of Probiotic Therapy on the Endocannabinoid System, Pain, Sleep and Fatigue: A Randomized, Double-Blind, Placebo-Controlled Trial in Dancers. Wiącek J, Podgórski T, Kusy K, et al. Int J Mol Sci, 2024. The rugby trial found less muscle soreness with the probiotic. It also found that sleep scores improved as soreness and an inflammation marker fell, but only across both groups combined. Its abstract does not report any difference in sleep between the probiotic and placebo groups [2]Probiotic supplementation elicits favourable changes in muscle soreness and sleep quality in rugby players. Harnett JE, Pyne DB, McKune AJ, et al. J Sci Med Sport, 2021.
Is it the same for people in general? Broadly, yes. A 2024 meta-analysis of 15 trials in the general population found better scores with probiotics on the Pittsburgh Sleep Quality Index (PSQI), a standard sleep questionnaire [4]Effects of probiotics on sleep parameters: A systematic review and meta-analysis. Ito H, Tomura Y, Kitagawa Y, et al. Clin Nutr ESPEN, 2024.
Article
What was studied
The review searched four databases up to September 2025. It looked for randomised trials that gave probiotics or synbiotics to athletes or other people who exercise, and that measured sleep. It included six trials: four of probiotics and two of synbiotics. They lasted 4 to 17 weeks and were published between 2019 and 2024 [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026. The authors did not pool the data into one estimate. Instead, they counted the direction of each result and combined the p-values with Fisher's method [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
The six trials
| Group | Country | Weeks | Sleep measure | Result for sleep |
|---|---|---|---|---|
| Female dancers (15) | Poland | 12 | PSQI questionnaire | A trend to better sleep quality, p = 0.078; no effect on sleep latency |
| Football players (19) | Malaysia | 8 | Brain waves, recorded by a headband | More theta and delta waves at week 4, p < 0.05 |
| Rugby players (19) | Australia | 17 | Self-rated sleep quality and amount | The review counts both as improved, p < 0.05; see the FAQ above |
| University runners (49) | Japan | 12 | PSQI questionnaire | No difference in sleep quality; less anxiety and fatigue |
| Soccer players and students (synbiotic) | Spain | 4 | Movement sensor, questionnaire | Better sleep efficiency and latency, in athletes only, p < 0.05 |
| Military recruits (65, synbiotic) | Brazil | 5 | PSQI, sleepiness | Less sleepiness, p < 0.001 in Table 1; only the synbiotic group reached "good sleep quality" |
Group sizes are taken from the review's Table 1 [1 Table 1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026. Four trials included only men, one only women, and one both [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
Limits of this evidence
- Small trials. The review reports 180 participants in total, but the group sizes in its own Table 1 add up to 194 [1 Table 1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
- Risk of bias. Five trials were rated "some concerns" and one "high risk", mainly because it was unclear whether the outcomes had been chosen in advance [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
- Rough statistics. Most p-values were reported only as below or above 0.05, and the combined p-values were calculated from these [1 Table 2]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
- Different products and measures. The trials used different strains, doses and sleep tests. One used heat-killed bacteria [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
- Mostly self-rated sleep. No trial used polysomnography [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
- Mostly men, short trials. The authors note that the results may not apply to women or to longer use [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
- Funding and ties. The authors report no external funding and no conflicts of interest [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026.
What the authors suggest
The authors suggest that probiotics or synbiotics could be tried alongside good sleep habits, with modest expectations, mainly for self-rated sleep [1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026. This is their view, not advice for you.
Talk to a doctor before you start a supplement, especially if you take medicines or are pregnant.
Verification
Checked on 2026-11-10.
| Claim | Result | What the check found |
|---|---|---|
| Probiotics tend to improve self-rated sleep quality (PSQI score) in people in general | Verified | A 2024 meta-analysis of 15 trials found that PSQI scores fell more with probiotics than with placebo, at 4-6 weeks and at 8-16 weeks. Read as abstract only [4]Effects of probiotics on sleep parameters: A systematic review and meta-analysis. Ito H, Tomura Y, Kitagawa Y, et al. Clin Nutr ESPEN, 2024 |
| In athletes, 9 of 12 sleep outcomes favoured the supplement | Partly verified | Two of the nine are weak. The dancer trial reports only a non-significant trend (p = 0.078) [3]Evaluating the Impact of Probiotic Therapy on the Endocannabinoid System, Pain, Sleep and Fatigue: A Randomized, Double-Blind, Placebo-Controlled Trial in Dancers. Wiącek J, Podgórski T, Kusy K, et al. Int J Mol Sci, 2024. The rugby trial reports less soreness with the probiotic and links sleep to soreness across both groups combined; its abstract shows no sleep difference between the groups [2]Probiotic supplementation elicits favourable changes in muscle soreness and sleep quality in rugby players. Harnett JE, Pyne DB, McKune AJ, et al. J Sci Med Sport, 2021. Two of the twelve outcomes are brain-wave readings, not direct measures of sleep |
| Combined p-values show an overall effect (probiotics p < 0.01, synbiotics p < 0.001) | Not verified | No second source repeats this. The review gives most p-values only as "below" or "above" 0.05 [1 Table 2]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026 |
| 180 people took part in the six trials | Partly verified | The group sizes in the review's own Table 1 add up to 194 [1 Table 1]The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026 |
| Probiotics and synbiotics showed no safety problems | Not verified | The review says so, but no second source on safety in athletes was found |
| The effects are clearest for sleep quality and sleep latency | Opinion | This is the authors' reading of the tally. Among the probiotic trials, only the dancer trial measured sleep latency, and it found no effect [3]Evaluating the Impact of Probiotic Therapy on the Endocannabinoid System, Pain, Sleep and Fatigue: A Randomized, Double-Blind, Placebo-Controlled Trial in Dancers. Wiącek J, Podgórski T, Kusy K, et al. Int J Mol Sci, 2024 |
Sources
The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. Salehi Asl M, Ahmadi F, Ershadmanesh M, et al. J Int Soc Sports Nutr, 2026
Systematic review · About this source