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Time of the day of exercise impact on cardiovascular disease risk factors in adults: a systematic review and meta-analysis.
Sevilla-Lorente, R, Carneiro-Barrera, A, Molina-Garcia, P, Ruiz, JR, Amaro-Gahete, FJ
Journal of science and medicine in sport. 2023;26(3):169-179
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In humans, shifted sleep patterns seem to interfere with several metabolic pathways. Shift work, short sleep duration, exposure to artificial light, inadequate eating time window, and lack of physical activity, are some characteristics of the modern lifestyle that contributes to the occurrence and worsening of cardiovascular disease (CVD). The aim of this study was to analyse the time of the day of exercise-induced effects on CVD risk factors in adults. This study was a systematic review and meta-analysis of twenty-two studies. Results showed that exercise produces an acute reduction of systolic blood pressure independently of the time of the day at which it is performed. Similarly, exercise produces an acute increase in blood glucose independently of the time of the day. Authors concluded that further research is needed to establish whether there is a diurnal variation of exercise on cardiovascular health and how it is related to health status, sex, or the type of exercise.
Abstract
OBJECTIVES To compare the effect of a single bout of morning vs. evening exercise on cardiovascular risk factors in adults. DESIGN Systematic review and meta-analysis. METHODS A systematic search of studies was conducted using PubMed and Web of Science from inception to June 2022. Selected studies accomplished the following criteria: crossover design, acute effect of exercise, blood pressure, blood glucose, and/or blood lipids as the study's endpoint, a washout period of at least 24 h, and adults. Meta-analysis was performed by analyzing: 1) separated effect of morning and evening exercise (pre vs. post); and 2) comparison between morning and evening exercise. RESULTS A total of 11 studies were included for systolic and diastolic blood pressure and 10 studies for blood glucose. Meta-analysis revealed no significant difference between morning vs. evening exercise for systolic blood pressure (g ∆ = 0.02), diastolic blood pressure (g ∆ = 0.01), or blood glucose (g ∆ = 0.15). Analysis of moderator variables (age, BMI, sex, health status, intensity and duration of exercise, and hour within the morning or evening) showed no significant morning vs. evening effect. CONCLUSIONS Overall, we found no influence of the time of the day on the acute effect of exercise on blood pressure neither on blood glucose.
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The Sleep-Immune Crosstalk in Health and Disease.
Besedovsky, L, Lange, T, Haack, M
Physiological reviews. 2019;99(3):1325-1380
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The interaction between sleep and immunity is an established phenomena. This thorough review article summarises sleep changes in response to both infectious and non-infectious immune system challenges and describes the role of sleep in supporting the immune system. Details are provided of how sleep affects the innate immune system (first line, rapid defence against infection) as well as the adaptive immune system (second line, delayed defence against infection), using a feedback system which promotes host defence. Sleep is associated with reduced infection risk and can improve infection outcome and vaccination responses. Sleep deprivation is also associated with chronic, low-grade inflammation. Nutrition Practitioners wishing to support immunity can focus on sleep as a simple lifestyle measure to enhance resilience.
Abstract
Sleep and immunity are bidirectionally linked. Immune system activation alters sleep, and sleep in turn affects the innate and adaptive arm of our body's defense system. Stimulation of the immune system by microbial challenges triggers an inflammatory response, which, depending on its magnitude and time course, can induce an increase in sleep duration and intensity, but also a disruption of sleep. Enhancement of sleep during an infection is assumed to feedback to the immune system to promote host defense. Indeed, sleep affects various immune parameters, is associated with a reduced infection risk, and can improve infection outcome and vaccination responses. The induction of a hormonal constellation that supports immune functions is one likely mechanism underlying the immune-supporting effects of sleep. In the absence of an infectious challenge, sleep appears to promote inflammatory homeostasis through effects on several inflammatory mediators, such as cytokines. This notion is supported by findings that prolonged sleep deficiency (e.g., short sleep duration, sleep disturbance) can lead to chronic, systemic low-grade inflammation and is associated with various diseases that have an inflammatory component, like diabetes, atherosclerosis, and neurodegeneration. Here, we review available data on this regulatory sleep-immune crosstalk, point out methodological challenges, and suggest questions open for future research.
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Bridging the Reciprocal Gap between Sleep and Fruit and Vegetable Consumption: A Review of the Evidence, Potential Mechanisms, Implications, and Directions for Future Work.
Noorwali, E, Hardie, L, Cade, J
Nutrients. 2019;11(6)
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Both sleep disruption and a low intake of fruit and vegetables (FV) are associated with higher rates of premature death and chronic disease. This review looked at previous studies in order to determine whether there is a link between sleep and FV consumption. A recent meta-analysis found that shorter sleep duration is consistently associated with low fruit and vegetable intake in children, but in adults the association is less clear. Studies looking at the effect of sleep on FV intake had variable results. Tart cherries and kiwi fruits were the most commonly studied fruits for their effect on sleep measures. Observational studies tended to find that both short- and long-sleepers tend to eat less FV than those that sleep for 7-8 hours. A lot of evidence shows that people who go to sleep later (‘owls’) tend to consume unhealthier diets with lower intakes of FV than people who go to bed earlier (‘larks’). The researchers also looked at potential mechanisms for the association between sleep and FV intake. Polyphenols in FV may influence sleep by increasing neurotransmitters via the gut-brain axis, improving energy metabolism and through alterations in circadian rhythms and the CLOCK genes. Ways in which disrupted sleep may affect FV consumption included changes in hunger hormones, emotional stress and impaired decision making. With further research, interactions between sleep measures and FV consumption may be clarified and potentially reduce the burden of chronic diseases and premature deaths.
Abstract
A substantial burden of disease and mortality globally is attributable to both sleep disruption and low intakes of fruit and vegetable (FV) and there is increasing mechanistic and epidemiological evidence to support a reciprocal relationship between the two. This review provides an overview of experimental and observational studies assessing the relations between sleep and FV consumption from 52 human adult studies. Experimental studies are currently limited and show inconsistent results. Observational studies support a non-linear association with adults sleeping the recommended 7-9 hours/day having the highest intakes of FV. The potential mechanisms linking sleep and FV consumption are highlighted. Disrupted sleep influences FV consumption through homeostatic and non-homeostatic mechanisms. Conversely, FV consumption may influence sleep through polyphenol content via several potential pathways. Few human experimental studies have examined the effects of FV items and their polyphenols on sleep and there is a need for more studies to address this. An appreciation of the relationship between sleep and FV consumption may help optimize sleep and FV consumption and may reduce the burden of chronic diseases. This review provides implications for public health and directions for future work.
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Yoga for anxiety: A systematic review and meta-analysis of randomized controlled trials.
Cramer, H, Lauche, R, Anheyer, D, Pilkington, K, de Manincor, M, Dobos, G, Ward, L
Depression and anxiety. 2018;35(9):830-843
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While temporary anxiety is a natural response, excessive and prolonged anxiety can lead to a wide range of physical symptoms and behavior changes. Current treatment options include psychological approaches and medication, however many individuals experiencing anxiety choose to self-manage their condition. Yoga has become a popular approach to improve emotional well-being, and based on a recent study, yoga practitioners have reported managing stress and anxiety as one of the main reasons for practicing. The aim of this meta-analysis was to review the effectiveness and safety of yoga for anxiety. Eight studies with 319 participants were included in this systematic review. Among these studies, no effects were found for patients with anxiety disorders diagnosed by the Diagnostic and Statistical Manual (DSM) criteria, only for patients without a formal diagnosis. Based on these results, the authors conclude yoga may be beneficial in the short-term for individuals with elevated levels of anxiety, however there was no conclusive evidence for individuals when only DSM-diagnosed anxiety disorders were considered. These findings warrant further studies to better understand the connection between mindfulness practices and anxiety.
Abstract
Yoga has become a popular approach to improve emotional health. The aim of this review was to systematically assess and meta-analyze the effectiveness and safety of yoga for anxiety. Medline/PubMed, Scopus, the Cochrane Library, PsycINFO, and IndMED were searched through October 2016 for randomized controlled trials (RCTs) of yoga for individuals with anxiety disorders or elevated levels of anxiety. The primary outcomes were anxiety and remission rates, and secondary outcomes were depression, quality of life, and safety. Risk of bias was assessed using the Cochrane tool. Eight RCTs with 319 participants (mean age: 30.0-38.5 years) were included. Risk of selection bias was unclear for most RCTs. Meta-analyses revealed evidence for small short-term effects of yoga on anxiety compared to no treatment (standardized mean difference [SMD] = -0.43; 95% confidence interval [CI] = -0.74, -0.11; P = .008), and large effects compared to active comparators (SMD = -0.86; 95% CI = -1.56, -0.15; P = .02). Small effects on depression were found compared to no treatment (SMD = -0.35; 95% CI = -0.66, -0.04; P = .03). Effects were robust against potential methodological bias. No effects were found for patients with anxiety disorders diagnosed by Diagnostic and Statistical Manual criteria, only for patients diagnosed by other methods, and for individuals with elevated levels of anxiety without a formal diagnosis. Only three RCTs reported safety-related data but these indicated that yoga was not associated with increased injuries. In conclusion, yoga might be an effective and safe intervention for individuals with elevated levels of anxiety. There was inconclusive evidence for effects of yoga in anxiety disorders. More high-quality studies are needed and are warranted given these preliminary findings and plausible mechanisms of action.
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A systematic review and meta-analysis of cognitive and behavioral interventions to improve sleep health in adults without sleep disorders.
Murawski, B, Wade, L, Plotnikoff, RC, Lubans, DR, Duncan, MJ
Sleep medicine reviews. 2018;40:160-169
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Sleep is important for good health but more than a quarter of the adult population reports poor quality sleep. This review and meta-analysis looked at cognitive and behavioural interventions in adults who report poor sleep but are not diagnosed with a clinical sleep disorder. The most commonly used interventions were stress management/relaxation, meditation, controlled breathing and stimulus control. A meta-analysis showed a medium improvement of overall sleep quality and a small but significant improvement of subjective sleep quality and duration with cognitive and behavioural interventions. The effects were bigger when sleep at baseline was worse. Effects of mode of delivery, study duration and the inclusion of a relaxation component were not assessed, due to insufficient numbers. The authors conclude that there is room for improvements of cognitive and behavioural interventions and call for more investigations into this.
Abstract
Many adults without a diagnosed sleep disorder report poor sleep health, which is defined by dissatisfactory levels of sleep duration, sleep quality, or the timing of sleep. No previous review has summarized and described interventions targeting poor sleep health in this population. This meta-analysis aimed to quantify the efficacy of behavioral and cognitive sleep interventions in adults with poor sleep health, who do not have a sleep disorder. Electronic databases (Medline, Embase, PsycInfo, Cinahl) were searched with restrictions for age (18-64 y) and English language full-text, resulting in 18,009 records being screened and 592 full-texts being assessed. Eleven studies met inclusion criteria, seven of which reported a measure of overall sleep health (Pittsburgh sleep quality index [PSQI]). Following appraisal for risk of bias, extracted data were meta-analyzed using random-effects models. Meta-analyses showed interventions had a medium effect on sleep quality (Hedge's g = -0.54, [95% confidence interval (CI)] -0.90 to -0.19, p < 0.01). Baseline sleep health was the only significant effect moderator (p = 0.01). The most frequently used intervention components were stress management and relaxation practice, stimulus control, sleep hygiene, and exercise. Interventions targeting cognitive and behavioral self-regulation improve sleep quality in adults without clinical sleep disorder.
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Circadian Rhythms, Metabolism, and Chrononutrition in Rodents and Humans.
Johnston, JD, Ordovás, JM, Scheer, FA, Turek, FW
Advances in nutrition (Bethesda, Md.). 2016;7(2):399-406
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Chrononutrition is an emerging field that links the body’s metabolism to its endogenous circadian rhythm. It is now recognised that numerous circadian clocks are found within all major tissues and most cells of the body. This complex network of clocks influences a wide range of biological processes including neuronal, endocrine, metabolic and behavioural function. When there is a disruption in a single circadian clock, whole-organism homeostasis can be impacted, potentially resulting in the development of disease. This review explains the potential mechanisms by which circadian clocks influence biological processes through transgenic animal studies, and how they are being translated to human genetics and metabolomics. The principles of chrononutrition are clinically significant factors that should be considered when managing and treating metabolic disease, as well as maintaining health in the general population.
Abstract
Chrononutrition is an emerging discipline that builds on the intimate relation between endogenous circadian (24-h) rhythms and metabolism. Circadian regulation of metabolic function can be observed from the level of intracellular biochemistry to whole-organism physiology and even postprandial responses. Recent work has elucidated the metabolic roles of circadian clocks in key metabolic tissues, including liver, pancreas, white adipose, and skeletal muscle. For example, tissue-specific clock disruption in a single peripheral organ can cause obesity or disruption of whole-organism glucose homeostasis. This review explains mechanistic insights gained from transgenic animal studies and how these data are being translated into the study of human genetics and physiology. The principles of chrononutrition have already been demonstrated to improve human weight loss and are likely to benefit the health of individuals with metabolic disease, as well as of the general population.