Do probiotics help with sleep? What the research does and doesn't show

The evidence does not support probiotics as a sleep aid or as a treatment for insomnia. Reviews of placebo-controlled trials found small improvements in sleep-quality questionnaire scores, but the studies varied widely in strain, duration and population, some had a risk of bias, and a review in working adults found too little data to draw conclusions on sleep.

What the evidence doesn't support

• No insomnia treatment was shown: the reviews measured questionnaire scores, and their authors called for further trials.
• A bedtime effect. We found no trial that tested taking a probiotic before sleep versus another time.
• A consistent result. In 66 postmenopausal women given probiotic yogurt for six weeks, sleep quality did not differ from ordinary yogurt.
• A strain or dose to choose. The effect varied with strain type, duration and the health of participants.

What the trials found

Reviews of randomized trials

A 2024 systematic review and meta-analysis of 15 placebo-controlled randomized trials found Pittsburgh Sleep Quality Index scores improved more with probiotics than placebo after 4 to 6 weeks and after 8 to 16 weeks, and two factors of the OSA sleep inventory ("sleepiness on rising" and "refreshing") improved. Some studies had a risk of bias. A second 2024 meta-analysis of 11 randomized trials in adults with sleep disorders or sub-healthy sleep found a pooled effect of -0.34 (95% CI -0.56 to -0.13) favouring probiotics or paraprobiotics, varying with participants' health, duration, strain and test criteria. A 2025 analysis of 72 trials of probiotics, prebiotics and synbiotics, which included 12 sleep studies, found sleep quality improved (SMD -0.39, 95% CI -0.53 to -0.25), and cited high heterogeneity and limited methodological quality. Doses and strains varied across all three.

Where the data thin out

A 2026 review of 12 trials in 3,350 healthy working adults found a modest benefit on depression, anxiety and stress symptoms but said there was too little evidence to draw conclusions on sleep quality. In the 66-woman trial (100 g a day of probiotic yogurt for six weeks, strain not stated), anxiety and stress scores were slightly lower than with ordinary yogurt, but sleep quality and depression did not differ.

Questions people ask

Do probiotics help with sleep?

Reviews found small improvements in questionnaire scores with considerable variation between studies. That is a signal worth testing, not evidence that a probiotic is a sleep aid.

Why take probiotics before sleep?

We found no trial showing a bedtime advantage. Timing for survival through the stomach is a separate question covered in best time to take probiotics.

See also probiotics and stress, probiotics and menopause and probiotics benefits.

When to talk to a doctor

A probiotic is not a treatment for insomnia or any sleep disorder. Trouble sleeping for more than a few weeks, loud snoring with pauses in breathing, daytime sleepiness that affects driving, or low mood with poor sleep should be assessed by a doctor. Ask a doctor or pharmacist before starting a probiotic if you have a weakened immune system or take prescription medicine.