Summary: A new clinical study finds that short-term sleep loss can change the composition of gut bacteria previously associated with obesity and type 2 diabetes in humans.
Source: Uppsala University.
New clinical results from Uppsala University indicate that restricting sleep alters the relative abundance of specific gut bacteria linked to impaired metabolic health. The study is published in the journal Molecular Metabolism.
Alterations in the composition and diversity of the gut microbiota have been connected to metabolic disorders such as obesity and type 2 diabetes. These conditions are also associated with chronic sleep loss, but whether short-term sleep restriction directly affects the human gut microbiota was previously unknown. To address this gap, researchers at Uppsala University, led by Christian Benedict (associate professor of neuroscience) and Jonathan Cedernaes (M.D., Ph.D.), collaborated with the German Institute of Human Nutrition Potsdam-Rehbruecke. They conducted a controlled clinical study to examine whether brief periods of reduced sleep change gut microbial communities in healthy individuals.
The study enrolled nine healthy, normal-weight young men and used a randomized within-subject crossover design with standardized in-lab conditions, fixed meal times, and controlled physical activity. Participants underwent two conditions: two consecutive nights of partial sleep deprivation (PSD), with a restricted sleep opportunity of roughly four hours per night, and two nights of normal sleep (NS), with an approximate eight-hour sleep opportunity. Fecal samples were collected before and after each intervention, and participants completed oral glucose tolerance tests to evaluate metabolic responses.
Overall, the researchers did not observe significant changes in microbial diversity after two nights of sleep restriction. Given the short duration and the small sample size, a lack of broad diversity shifts was not unexpected. However, more targeted analyses identified specific compositional changes in bacterial groups that have been associated with metabolic disturbances in previous human and animal studies. Notably, partial sleep deprivation was linked to an increased Firmicutes:Bacteroidetes ratio and higher relative abundance of the bacterial families Coriobacteriaceae and Erysipelotrichaceae, together with a reduction in Tenericutes. These shifts mirror patterns reported in some studies comparing obese and normal-weight individuals.
“We did not find evidence that the overall diversity of the gut microbiota was changed by this short-term sleep restriction,” says senior author Jonathan Cedernaes. “Still, the shifts in certain bacterial groups parallel changes previously linked to obesity and metabolic dysfunction. Larger and longer clinical sleep interventions will be necessary to determine whether sleep-related microbiota changes play a causal role in weight gain, insulin resistance, or other metabolic consequences of chronic sleep loss.”
In addition to microbiota assessments, the study measured insulin sensitivity. Participants became more than 20 percent less insulin sensitive after the sleep-restricted condition. Insulin is the pancreatic hormone that lowers blood glucose, and reduced insulin sensitivity (insulin resistance) is a hallmark of impaired glucose metabolism. Importantly, the observed decrease in insulin sensitivity did not correlate with the measured changes in gut microbiota following sleep loss.
“The reduction in insulin sensitivity following short-term sleep loss appears to be independent of the microbiota alterations detected in our study,” explains first author Christian Benedict. “This suggests that, at least over the short term, changes in the gut microbiome may not be the primary driver of immediate insulin resistance after a few nights of curtailed sleep.”
The authors emphasize that the human gut microbiome is highly complex and that its full functional roles remain incompletely understood. Future research should explore how individual differences in microbiota composition and function influence susceptibility to the metabolic and cognitive effects of sleep loss. Longer and larger studies, including participants with pre-existing metabolic disorders, will be important to clarify whether sleep-related microbiome changes contribute directly to adverse health outcomes.
Source: Jonathan Cedernaes – Uppsala University
Image source: Illustrative image used for context only.
Original research: Abstract for “Gut Microbiota and Glucometabolic Alterations in Response to Recurrent Partial Sleep Deprivation in Normal-weight Young Individuals” by Christian Benedict, Heike Vogel, Wenke Jonas, Anni Woting, Michael Blaut, Annette Schürmann, and Jonathan Cedernaes, published in Molecular Metabolism (online October 24, 2016). DOI: 10.1016/j.molmet.2016.10.003
Abstract
Gut Microbiota and Glucometabolic Alterations in Response to Recurrent Partial Sleep Deprivation in Normal-weight Young Individuals
Objective
Alterations of the gut microbial community have been proposed to promote metabolic disturbances similar to those seen after short periods of sleep loss, such as reduced insulin sensitivity. However, whether sleep restriction itself changes the gut microbiota in humans remained unclear.
Methods
In a randomized within-subject crossover study with standardized laboratory conditions, nine normal-weight men were studied on two occasions: after two nights of partial sleep deprivation (sleep opportunity approximately 02:45–07:00) and after two nights of normal sleep (sleep opportunity approximately 22:30–07:00). Fecal samples were collected within 24 hours before and after each condition, and each participant completed an oral glucose tolerance test following the intervention.
Results
Sequencing analysis of the V4 region of the 16S rRNA gene revealed that two nights of partial sleep deprivation, compared with normal sleep, led to an increased Firmicutes:Bacteroidetes ratio and higher relative abundance of Coriobacteriaceae and Erysipelotrichaceae, along with decreased Tenericutes (all P < 0.05). These taxonomic shifts have been associated with metabolic perturbations in prior studies. No significant effects were found on overall beta diversity or on fecal short-chain fatty acid concentrations. Fasting and postprandial measures indicated decreased insulin sensitivity after sleep restriction (all P < 0.05).
Discussion
The findings show that short-term sleep loss produces modest but specific changes in human gut microbiota composition. Whether these microbiota changes contribute meaningfully to metabolic consequences of sleep deprivation requires further study in larger, longer interventions and in populations with existing metabolic impairment.