Researchers tested whether two types of helpful bacteria called probiotics could reduce anxiety in rats whose sleep schedules were disrupted. They gave one group of rats these special bacteria while keeping their sleep patterns irregular for 30 days. The rats that received one type of bacteria (Lactobacillus rhamnosus) showed less anxiety and explored their surroundings more confidently than rats without the bacteria. The study suggests that probiotics might help protect our brains and emotions when our sleep schedules get messed up, though more research in humans is needed to confirm these findings.

The Quick Take

  • What they studied: Whether two types of beneficial gut bacteria could reduce anxiety and stress caused by disrupted sleep schedules
  • Who participated: 42 adult male rats divided into six groups, with most experiencing 30 days of irregular light-dark cycles (4 hours dark, 20 hours light) that mimicked sleep disruption
  • Key finding: Rats receiving Lactobacillus rhamnosus bacteria showed significantly less anxiety and more exploratory behavior compared to rats without the bacteria, while the other bacteria type (Lactobacillus delbrueckii) was less effective
  • What it means for you: This early research suggests probiotics might help protect mental health during stressful periods with irregular sleep, but these are animal studies and human research is needed before recommending probiotics as an anxiety treatment

The Research Details

Scientists used 42 adult male rats and divided them into six different groups. Most groups experienced 30 days of disrupted sleep patterns (only 4 hours of darkness and 20 hours of light each day), which is stressful for rats. While experiencing this sleep disruption, some groups received daily doses of helpful bacteria through a feeding tube. The researchers collected stool samples before and after the study to confirm the bacteria were actually living in the rats’ digestive systems. They used two standard tests to measure anxiety: the open-field test (watching how confidently rats explore a new space) and the elevated plus maze test (seeing if rats avoid high, open areas, which anxious animals tend to do).

The study design allowed researchers to compare three things: how the disrupted sleep affected behavior, whether the bacteria helped, and which type of bacteria worked better. By measuring the bacteria in stool samples using genetic testing, they confirmed the probiotics survived in the rats’ digestive systems throughout the study.

This research approach matters because it tests a potential natural alternative to anxiety medications, which can have unwanted side effects. By using a controlled animal study, researchers can carefully measure anxiety changes and confirm that the bacteria actually reach the gut. The study also examines the gut-brain connection, which is an emerging area of science suggesting that bacteria in our digestive system can influence our emotions and stress levels.

This is a controlled laboratory study with clear groups for comparison, which is a solid research design. The researchers confirmed the bacteria were present using genetic testing, which adds credibility. However, this is an animal study using rats, not humans, so results may not directly apply to people. The sample size of 42 rats is reasonable for this type of research. The study was published in a peer-reviewed journal, meaning other scientists reviewed it before publication. One limitation is that only male rats were used, so results might differ for females.

What the Results Show

The disrupted sleep schedule (4 hours dark, 20 hours light) caused rats to show increased anxiety and reduced exploration, confirming that irregular sleep is stressful for animals. When rats received Lactobacillus rhamnosus bacteria, they showed significantly improved behavior—they were less anxious and explored their surroundings more like normal, healthy rats. The improvement was noticeable enough that researchers could measure it using standard anxiety tests.

Interestingly, the other bacteria type (Lactobacillus delbrueckii) also helped, but not as much as Lactobacillus rhamnosus. This suggests that different probiotic strains have different effects on anxiety and mood. The genetic testing confirmed that both types of bacteria successfully colonized the rats’ digestive systems during the 30-day study period, meaning the bacteria were actually living and working in their guts.

The study found that the presence of probiotics in the gut appeared to influence brain function and behavior through what scientists call the ‘gut-brain axis’—essentially a communication system between the digestive system and the brain. The researchers suggest that beneficial bacteria may produce compounds that travel through the body and affect mood and anxiety centers in the brain. The fact that one bacteria type worked better than the other suggests that specific strains matter, not just any probiotic.

This research builds on growing evidence that gut bacteria influence mental health and stress responses. Previous studies have suggested links between probiotics and reduced anxiety, but this study specifically tests how probiotics might help during sleep disruption, which is a common stressor in modern life. The findings align with other research showing that Lactobacillus species can affect behavior and mood, though most previous work has been in different stress conditions.

This study used only male rats, so results might be different for females. The study lasted only 30 days, so we don’t know if benefits continue longer or if tolerance develops. The dose and type of bacteria used in rats may not translate directly to humans—people would need different amounts. The study didn’t test whether the bacteria would help with anxiety from other causes, only from sleep disruption. Additionally, this is animal research, and animal studies don’t always produce the same results in humans due to differences in biology and behavior.

The Bottom Line

Based on this animal research, probiotics show promise as a potential natural approach to managing anxiety related to sleep disruption (moderate confidence level). However, human studies are needed before probiotics can be recommended as a treatment. If you’re interested in trying probiotics for anxiety, consult your doctor first, as they can advise whether it’s appropriate for your situation and recommend proper strains and doses.

People with irregular sleep schedules (shift workers, travelers, people with jet lag) might eventually benefit from this research. People seeking natural alternatives to anxiety medications should find this interesting but should wait for human studies. People with anxiety from other causes should not assume probiotics will help without more research. This research is preliminary and shouldn’t replace professional mental health treatment.

In this animal study, benefits appeared within the 30-day treatment period. If similar effects occur in humans, you might expect to notice changes within several weeks, though this is speculative. Long-term effects and whether benefits persist after stopping probiotics are unknown and would require additional research.

Want to Apply This Research?

  • Track sleep schedule consistency (hours of sleep at regular times) and daily anxiety levels using a simple 1-10 scale. Note any probiotic use and brand/strain. Monitor for patterns between sleep regularity and anxiety over 4-8 weeks.
  • If using the app to manage anxiety related to sleep disruption, set reminders for consistent sleep times and track whether maintaining a regular schedule reduces anxiety. If trying probiotics, log daily intake and rate anxiety levels to see if there’s a correlation with consistent probiotic use.
  • Create a weekly summary comparing sleep consistency, anxiety ratings, and probiotic adherence. Look for patterns over 4-week periods. Share data with your healthcare provider to determine if probiotics are helping your specific situation. Adjust sleep schedule consistency first, as this study suggests sleep regularity is crucial for anxiety management.

This research was conducted in rats and has not been tested in humans. Probiotics are not approved by the FDA as a treatment for anxiety or stress. If you experience anxiety or sleep problems, consult a healthcare provider before starting any probiotic supplement. This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment. Individual results may vary, and probiotics may interact with medications or cause side effects in some people.