When going through stressful times, it can be hard to get a good night's sleep. Now, researchers suggest that dietary prebiotics might be effective against stress-induced insomnia.
First study author Robert Thompson, of the Department of Integrative Physiology at the University of Colorado Boulder, and colleagues recently reported their findings in the journal Frontiers in Behavioral Neuroscience.
According to the American Psychological Association, stress is a key player in sleep loss. Approximately 47 percent of adults in the United States report a lack of sleep due to stress, and 21 percent report that poor sleep further exacerbates their stress.
Thompson and team note that previous studies have suggested that stress can alter gut bacteria in a way that interferes with the sleep-wake cycle. Until now, it was unclear whether prebiotics might help to improve sleep in the face of stress.
Prebiotics are nondigestible food components - found in chicory, artichokes, onions, leeks, and other vegetables - that fuel the growth of "good" gut bacteria. Research has indicated that when these good bacteria digest prebiotic fiber, they release byproducts that can affect brain function.
More REM sleep for stressed mice fed a prebiotic diet
For their study, Thompson and colleagues put male rats on one of two diets for 4 weeks: a diet supplemented with prebiotics or a standard chow diet (the control diet).
On analyzing fecal samples from the rodents after 4 weeks, the team found that rats that were fed the prebiotic diet showed an increase in beneficial gut bacteria - including Lactobacillus rhamnosus, known to aid immune system function - compared with rats fed the control diet.
Using electroencephalography to measure the rats' sleep-wake cycles, the researchers found that rats fed the prebiotic diet also had more non-rapid eye movement (NREM) sleep (the restorative sleep stage) compared with rodents fed the control diet.
"Given that sufficient NREM sleep and proper nutrition can impact brain development and function and that sleep problems are common in early life, it is possible that a diet rich in prebiotics started in early life could help improve sleep, support the gut microbiota and promote optimal brain/psychological health," note the authors.
When both groups of rats were exposed to acute stress (induced by tail shocks), the researchers found that the group fed the prebiotic diet had more rapid eye movement (REM) sleep than the group fed the control diet. The team notes that REM is the sleep stage associated with better recovery from stress.
Additionally, the researchers found that the rats fed the prebiotic diet were less likely to experience abnormalities in body temperature that can arise as a result of stress-induced alterations to gut bacteria.
Prebiotics might 'provide stress-protective effects on sleep-wake behavior'
While further studies are needed to better determine how prebiotics affect sleep quality, the researchers believe that their findings suggest that dietary prebiotics might offer benefits.
The team concludes:
"These data are the first to show that a diet rich in prebiotics can modulate the sleep-wake cycle both before and after stress and induce stress-protective effects in diurnal physiology and the gut microbiota.
Our results, however, cannot address how increases in Lactobacillus rhamnosus or other changes in microbial community structure contribute to the observed effects of a diet rich in prebiotics and more work is necessary to further elucidate the potential mechanisms. Nonetheless, our work is the first to demonstrate that consumption of a prebiotic diet can provide stress-protective effects on sleep-wake behavior."