Consumption of OLL1073R-1 yogurt improves psychological quality of life in women healthcare workers: secondary analysis of a randomized controlled trial

Effects of probiotics on sleep parameters: A systematic review and meta-analysis

AIM

Although sleep is essential for maintaining good health and well-being, sleep disorders are becoming increasingly prevalent. Probiotics may play a role in sleep regulation; therefore, this study aimed to provide a comprehensive overview of the effects of probiotics on sleep parameters.

METHODS

We conducted a systematic literature review and meta-analysis, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology. Relevant placebo-controlled randomized controlled trials examining the effects of probiotics on sleep outcomes were identified through systematic searches in the PubMed, Cochrane Library, and Ichushi databases. Data were extracted from eligible studies and the risk of bias was assessed. Statistical analyses were performed to assess the effects of probiotics on various sleep-related variables.

RESULTS

Fifteen randomized controlled trials were included in this review. The decrease in Pittsburgh Sleep Quality Index (PSQI) scores in the probiotics group was significantly lower than that in the placebo group after 4-6 weeks and 8-16 weeks, indicating improved sleep quality. The Oguri-Shirakawa-Azumi (OSA) sleep inventory score was also decreased in the probiotics group for Factor 1 "sleepiness on rising" and Factor 4 "refreshing," indicating improved sleep quality. Some studies however, showed a risk of bias.

CONCLUSION

This systematic review and meta-analysis indicated that probiotics may improve sleep quality, as measured by the PSQI and OSA sleep inventory. However, further research is needed to better understand the effects of probiotics on specific sleep parameters and address the limitations of existing studies.

Associations between Milk Intake and Sleep Disorders in Chinese Adults: A Cross-Sectional Study

We aimed to examine the association of milk intake with sleep disorders and their specific indicators. The current study included 768 adults aged 28-95 from Wenling, China. Milk intake was assessed using a food frequency questionnaire with ten food items, while sleep disorders were measured using the Pittsburgh Sleep Quality Index (PSQI), with higher scores indicating poorer sleep. The participants were divided into two groups according to the average intake of milk per week: rare intake (≤62.5 mL/week) and regular intake (>62.5 mL/week). Primary measurements were multivariate-adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for the prevalence of sleep disorders concerning regular milk intake compared with rare intake. In secondary analyses, linear regression analyses were performed to assess the effects of milk intake on sleep disorders and their specific dimensions. Regular intake of milk did not have a significant association with sleep disorders compared with rare intake (adjusted OR: 0.72, 95%; CI: 0.51, 1.03), but this association was found to be pronounced with sleep disturbances (OR: 0.49, 95%; CI: 0.28, 0.87). Increased intake of milk was significantly associated with the lower scores of PSQI for sleep quality (β: -0.045, 95%; CI: -0.083, -0.007) and sleep disturbances (β: -0.059, 95%; CI: -0.090, -0.029), respectively. When stratified by age and gender, the benefits of milk intake for sleep disorders and sleep disturbances were more significant in older adults (≥65) and men than in younger persons and women. In summary, regular milk intake benefits sleep quality, which may contribute to nutritional psychiatric support for prevention against sleep disorders.

Analysis of the Effects of Known Sleep-Support Supplements in Relation to Life Habits, Sleep Conditions, and Sleep Problems

Sleep is a crucial component of health, and insomnia is among the most common and vexing of life-habit-related disorders. While dietary sleep-support supplements can improve sleep, choosing an effective dietary supplement can be challenging for users due to the wide variety of options available and the varying effects experienced by different individuals. In this study, to identify new criteria for estimating the effects of dietary supplements, we examined the relationships among the dietary supplements, the pre-conditions (PCs; defined as the life habits and sleep conditions before supplementation), and the sleep problems of subjects before supplementation. An open, randomized, cross-over intervention trial enrolling 160 subjects was conducted to test the efficacy of each dietary supplement (Analysis 1) and the relationships among dietary supplements, the PCs, and sleep problems (Analysis 2). To this end, l-theanine (200 mg/day), γ-aminobutyric acid (GABA) (111.1 mg/day), Apocynum venetum leaf extract (AVLE) (50 mg/day), and l-serine (300 mg/day) were administered to subjects. Before the first intervention period, life habits and sleep conditions were surveyed to identify each subject's PCs. For each combination of supplements and sleep problems, PCs were compared between subjects whose sleep problems were improved and subjects whose sleep problems were not improved via supplementation. All the tested supplements were found to ameliorate sleep problems significantly (Analysis 1). In Analysis 2, the PCs specific to improved subjects were found to differ depending on the dietary supplements and sleep problems. In addition, subjects who consumed dairy products often showed improvement in their sleep problems with all the tested supplements. This study suggests the possibility of personalizing sleep-support supplementation based on personal life habits, sleep conditions, and sleep problems, in addition to the known efficacy of dietary supplements.

Exploring the Role of Dairy Products In Sleep Quality: From Population Studies to Mechanistic Evaluations

Poor sleep quality and insufficient sleep affect a large portion of the population. This is concerning given increasing evidence that poor sleep health is a behavioral risk factor for the development of cardiometabolic diseases. A healthy diet is associated with a plethora of favorable health outcomes, and emerging research now highlights diet as a potential determinant of sleep health that could be leveraged to improve sleep quality. Dairy products are notably rich in tryptophan (Trp), a key substrate for serotonin and melatonin production, which are instrumental for initiating and maintaining sleep. Furthermore, dairy products provide a range of micronutrients that serve as cofactors in the synthesis of melatonin from Trp, which could contribute to sleep-promoting effects. In this review, we evaluate population studies and clinical trials to examine a possible link between dairy consumption and sleep. Available epidemiologic studies illustrate positive associations between dairy intake and sleep outcomes. Moreover, some intervention studies support a causal effect of dairy intake on sleep. Given these data, we discuss potential mechanisms, invite additional clinical research on this topic, and provide insights on how limitations of current studies can be addressed in future trials.