A randomized controlled trial of 99 adults who reported poor sleep alongside symptoms of anxiety or depression found that a daily probiotic capsule produced measurably better sleep and lower mood scores after 12 weeks than a placebo. The findings were published in July 2025 in the peer-reviewed journal Brain Sciences and are notable because they combine gut microbiome analysis, inflammatory readouts and standardized mental health questionnaires in the same people.
Sleep efficiency, the share of time in bed actually spent asleep, climbed from 78.5% to 86.2% in the probiotic group. Depression scores on the PHQ-9 questionnaire fell from 12.3 to 7.8, and anxiety scores on the GAD-7 dropped from 10.5 to 6.2. Placebo participants barely moved on any of the three measures.
The trial ran across three Indian cities, Kolkata, New Delhi and Pune, and used stratified randomization by city and sex, with weekly telehealth check-ins for safety.
The two strains inside the capsule
The daily supplement combined two well-studied strains. Lactobacillus rhamnosus GG at 10 billion CFU (colony forming units) and Bifidobacterium longum at 5 billion CFU, taken as a single morning dose.
Also read: 7 warning signs of giant cell arteritis most people over 50 mistake for a headache
Post-trial stool samples showed higher gut diversity and larger populations of both bacteria in the probiotic group. Levels of butyrate and propionate, short-chain fatty acids produced by beneficial gut microbes, also rose.
Both strains are among the most studied in gut-brain research. Broader work has explored whether probiotics could ease anxiety symptoms in early trials, though the evidence base is still building.
What the wider evidence looks like
A larger meta-analysis in Frontiers in Psychiatry pooled 39 randomized trials with 4,094 participants and reported small but consistent improvements in self-reported sleep quality, along with a roughly 14-minute gain in total sleep time on objective measures.
A separate review in Frontiers in Nutrition, covering 13 trials and 890 adults, found a modest reduction in Pittsburgh Sleep Quality Index scores. Both reviews describe the effect as real but small and both flag that certainty of evidence remains low.
Also read: Heart rate variability by age: the ranges that reveal how well your body recovers
That fits the picture from the Indian trial. Probiotics are not sleep medication. They appear to shift the gut environment in ways that, in people with overlapping sleep and mood symptoms, may translate into meaningful improvements over weeks, not hours.
What to look for on a label
Product labels vary widely. Look for the specific strain name, such as Lactobacillus rhamnosus GG or Bifidobacterium longum, a stated CFU count and a use-by date, since live cultures lose potency over time.
Anyone already taking prescription medication for anxiety, depression or a sleep disorder should talk with their doctor before adding a supplement. Probiotics are not a substitute for treatment.
Also read: If you take Adderall or stimulant ADHD meds, these foods may cut how well they work
Also read: Taking warfarin? These common foods could work against your medication
This article is made and published by Jesper Bengtson, who may have used AI in the preparation.