During sleep, human beings recover from the physical and mental wear and tear generated during the day; in addition, a series of processes occur during sleep that is vital for the body's overall health, such as the restoration or conservation of energy, regulation of thermal, metabolic and endocrine function, immune activation, elimination of waste substances, regulation and restoration of brain electrical activity, synaptic homeostasis, high-impact cognitive processes, and memory consolidation. Therefore, it is important to enjoy a good "quality of sleep", a concept that represents the set of elements that make up the sleep process.
Good sleep quality can be affected by multiple factors and habits (e.g., age, gender, physical problems, changes in routines, mood, and lifestyle), which can impact both the physical and mental health of individuals. It has been shown that sleep disturbances have been associated with a decrease in academic and cognitive performance and work performance, an increase in the rate of traffic and occupational accidents, and a greater propensity to suffer from chronic degenerative diseases, such as obesity, hypertension, diabetes or cerebrovascular accidents, as well as mental disorders such as depression, anxiety, anguish, and stress.
When sleep disturbances are a symptom of another medical condition, the problem of falling asleep may be resolved by treating the underlying condition; however, when other causes are involved, the solution involves a combination of lifestyle changes and pharmacological treatments, most of which are not recommended for long periods due to possible adverse reactions (e.g., vertigo, muscle twitching, tremors, and spasms, among others).
As for lifestyle adjustments, it has been reported that changes in eating patterns could significantly improve sleep quality. For example, reducing excessive consumption of foods containing substances with direct stimulant action on the central nervous system (e.g., caffeine, theobromine, theophylline, biogenic amines) could help to better fall asleep.
The consumption of some foods and dietary supplements rich in L-tryptophan, vitamin B6 and magnesium may promote the synthesis of serotonin and melatonin, neurotransmitters involved in the wake-sleep cycle, which could benefit both the induction and maintenance of sleep.
Several studies have shown that sleep could be influenced by the state of the gut microbiota, due to bilateral connectivity through a signaling network known as the gut-brain axis. Therefore, it has been hypothesized that probiotic-based foods (live microorganisms that, when administered in adequate amounts, confer a health benefit on the host), could affect sleep and improve its quality through neuroendocrine, neurometabolic, and neuroimmunological mechanisms.
Bacterial metabolites and bacterial cell wall components are likely to play an important role in such sleep-generating mechanisms in the brain. For example, according to recent studies, butyrate, a fatty acid from the intestinal fermentation of dietary fiber, by the action of some intestinal bacteria, including probiotics, could promote sleep by activating specific receptors located in the liver and/or portal vein wall, which is involved in sleep signaling.
It has been reported that probiotics of the genera Bifidobacterium and Lactobacillus can produce neuroactive molecules (serotonin, gamma-aminobutyric acid, and acetylcholine) that play an important role in promoting sleep, in addition to increasing levels of melatonin, the sleep-regulating hormone.
It has also been documented that different components of the bacterial cell wall can cross the intestinal wall and regulate normal sleep patterns by directing the immune system to produce small pro-inflammatory proteins that increase sleep (somnogenic) and anti-inflammatory proteins that inhibit sleep (insomnogenic).
All this evidence suggests that the consumption of probiotic bacteria could be a coadjuvant alternative to pharmacological treatments to improve sleep quality, which has motivated the development of studies with large-scale clinical trial data to help describe the valuable effects of probiotics in improving sleep quality in the general population.
By Master of Science student Arantxa Almada Corral and researcher Adrián Hernández Mendoza. Source: CIAD