Researchers from Uppsala University published a new study in the journal, Molecular Metabolism, stating that sleep deprivation alters the level of gut bacteria that has previously been linked to dysfunctional metabolic health, including diseases like diabetes and insulin resistance.
The changes in the diversity and composition of the bacteria, or gut microbiota, have been directly associated to common chronic diseases like type 2 diabetes and obesity. Furthermore, these conditions are associated with loss of quality sleep. It is uncertain if sleep deprivation actually leads to the changes in the gut microbiota, however.
Keeping this thought in mind, Dr. Christian Benedict, neuroscience associate professor, along with Dr. Jonathan Cedernaes, MD, PhD, worked with scientists at the German Institute of Human Nutrition Potsdam-Rehbruecke on this project. They focused primarily on the sleep habits of nine healthy men who were of normal weight. They wanted to determine if restricting sleep to four hours a night for two days altered their gut bacteria. This was compared to people who get the normal amount of sleep, which is about eight hours a night.
Dr. Cedernaes noted in his findings that there was no evidence suggesting any changes in the diversity of the gut bacteria after restricting sleep. However, he does note that this was an expected result, given the short-term nature of the restriction and the very small sample size. When groups of bacteria were specifically analyzed in other studies, however, they did find changes in the gut that were similar to those found in obese patients when compared to people of normal weight.
As with all new findings, larger samples and longer clinical interventions are needed to completely investigate the extent of these microbiota alterations, as it is indicative in the other studies that these changes could have negative health consequences that are attributed to sleep loss, like insulin resistance and weight gain.
As noted by Dr. Benedict, the participants in this study were over 20% less sensitive to insulin after losing sleep. Insulin is a hormone produced by the pancreas and used to break down sugars in the blood. It is not clear if there is any link between sleep loss, gut bacteria changes, and this decreased insulin sensitivity. This tells us that, in the short term at least, there may not be a link between curtailed sleep, gut bacteria changes, and insulin sensitivity, so linking it to diabetes may not be indicated.
The gut microbiota analyzed in this study is extremely rich, but its functional role is not yet understood or characterized. In the future, research should be able to determine the functional role and composition of this microbiota, as well as determine whether it plays a role in how individual humans respond both metabolically and cognitively to sleep loss.
Rachael Herman is a professional writer with an extensive background in medical writing, research, and language development. Her hobbies include hiking in the Rockies, cooking, and reading.
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