“When experiencing a stressful event, the area of the brain that controls emotions, the amygdala, sends a distress signal to the hypothalamus, the brain’s command center,” explained Lucie Lingrand, a brain-gut axis specialist and product manager at Lallemand Health Solutions. “The hypothalamus then sends out an alert through the nervous system, which responds by releasing a flood of stress hormones, including adrenaline and cortisol.”
As the fight-or-flight response kicks in, digestion slows and gut sensitivity is increased. “Many studies in animal models of stress, as well as acute or chronic stress in human models, have shown that the intestinal barrier is impaired and that the composition of the gut microbiota is changed,”1,2 Lingrand said. “Stress in general can have a negative impact on the development of the intestinal barrier [and] when the body is repeatedly exposed to stress, it can initiate a vicious cycle of inflammation.”3
“If you feel like you are in a vicious cycle where stress is robbing you of good sleep and poor sleep is exacerbating your stress, it is not just your imagination,” agreed Jennifer Cooper, chief scientific officer, Savant Science. “The bidirectional nature of the gut-brain axis means not only that lack of sleep can make most conditions worse, including stressful ones, but it may even be the root cause of health concerns.”
Sleep is regulated by circadian rhythm and new research shows that even the microbiome exhibits diurnal rhythms. “Up to 60% of the gut microbiota, its gene expression and metabolic activity is linked to circadian genes,” Cooper noted, adding that the stress-regulating hypothalamic-pituitary-adrenal (HPA) axis also has a connection to the gut.4,5
“Everyone knows that our gut is loaded with both good and bad bacteria, but it also contains more than 100 million neurons and secretes at least 20 neurotransmitters identical to the ones produced in the brain,” she shared. “In fact, most of our serotonin (the mood hormone) is found in the gut.”
Stress, she said, activates the HPA axis and has been shown to decrease the population of lactobacilli and bacteroides in the gut.6 “Chronic stress also disrupts the intestinal barrier, which further contributes to microbiota dysbiosis and immune disfunction.”
To read this article in its entirety—including information about potential ingredients to help support stress and sleep formulations—check out the Sleep and stress – digital magazine.
Joanna Cosgrove is a Pennsylvania-based freelance writer who has covered the dynamic dietary supplement and healthy food and beverage industries for nearly 20 years.
1 Yarandi SS et al. “Modulatory Effects of Gut Microbiota on the Central Nervous System: How Gut Could Play a Role in Neuropsychiatric Health and Diseases.” J Neurogastroenterol Motil. 2016;22(2):201-212.
2 Kelly JR et al. “Breaking down the barriers: the gut microbiome, intestinal permeability and stress-related psychiatric disorders.” Front Cell Neurosci. 2015;9:392.
3 Smith F et al. “Early weaning stress impairs development of mucosal barrier function in the porcine intestine.” Am J Physiol Gastrointest Liver Physiol. 2010;298(3):G352-G363.
4 Parkar SG, Kalsbeek A, Cheeseman JF. “Potential Role for the Gut Microbiota in Modulating Host Circadian Rhythms and Metabolic Health.” Microorganisms. 2019;7(2):41.
5 Matenchuk BA, Mandhane PJ, Kozyrskyj AL. “Sleep, circadian rhythm, and gut microbiota.” Sleep Med Rev. 2020;53:101340.
6 Sudo N. “Chapter 13: the hypothalamic-pituitary-adrenal Axis and gut microbiota: a target for dietary intervention?” In: Hyland N, Stanton C, editors. The Gut-Brain Axis. Elsevier Inc.; 2016. p. 293e304.