Gut Microbiome Studies Link Higher Fiber Intake to Improved Sleep

Recent scientific studies have examined the relationship between dietary fiber, gut microbiota, and sleep quality, using data from both observational research and controlled trials. These findings offer insight into how food choices may influence sleep patterns through biological pathways.

Analysis of data from nearly 5,000 individuals in Japan using diet and sleep tracking apps indicated that consuming more fiber-rich foods was associated with falling asleep more quickly, experiencing fewer awakenings during the night, and achieving longer overall sleep. The same research also reported that higher protein intake correlated with an average increase of 10 to 11 minutes in nightly sleep duration.

In a separate randomized controlled trial, healthy adults in Japan were given an additional 6.4 grams per day of fermentable fiber for four weeks. This intervention led to measurable shifts in gut bacterial composition and increased levels of short-chain fatty acids in the body. Exploratory analysis from this trial suggested links between certain gut bacteria and improved sleep scores.

Population-based studies have also found that diets higher in fiber, whole grains, legumes, and fresh vegetables—foods known to support gut microbiota diversity—were associated with a lower prevalence of sleep disorders. These results suggest a connection between dietary habits and sleep health at the population level.

What the numbers show

• Nearly 5,000 individuals participated in the Japanese app-based study
• Protein intake was linked to 10–11 minutes longer sleep on average
• High-fiber group in a trial received about 6.4 g/day extra fermentable fiber
• Normal sleep duration group averaged 16.6 g/day fiber intake in NHANES data
• Short-chain fatty acids increased at two weeks in the high-fiber group

Scientific reviews have outlined how dietary fiber is processed by gut microbes into short-chain fatty acids, which can influence neurotransmitters involved in sleep regulation, such as serotonin, GABA, and melatonin. These biological processes are thought to play a role in how diet may affect sleep quality.

Further research using Mendelian randomisation methods with data from hundreds of thousands of individuals has suggested a two-way relationship between gut microbiome composition and insomnia. This means that certain gut bacteria may impact the risk of insomnia, while sleep patterns could also influence the makeup of gut bacteria.

Reviews have noted that prebiotic fibers, including partially hydrolysed guar gum, may support populations of short-chain fatty acid-producing bacteria. These bacteria are associated with reduced inflammation and improved nervous system function, both of which are relevant to sleep health.

Additional reviews have emphasized that increasing dietary fiber could help address sleep disturbances through the gut-brain axis. Mechanisms proposed include enhancing short-chain fatty acid production, improving gut barrier function, modulating inflammation, and increasing serotonin secretion. Observational data from NHANES indicated that individuals with normal sleep durations consumed more fiber on average than those with shorter or longer sleep durations.

* This article is based on publicly available information at the time of writing.