Exercise and melatonin in humans: reciprocal benefits

Exercise therapy in the application of sleep disorders

Sleep disorders often accompany neurological injuries, significantly impacting patient recovery and quality of life.The efficacy and adherence of traditional treatment methods have certain limitations. Exercise has been found to be a highly beneficial treatment method, capable of preventing and alleviating neurological injuries and sleep disorders. This article reviews relevant research findings from both domestic and international sources over the past few decades, systematically summarizing and analyzing the application of exercise therapy in sleep disorders,strategy of exercise intervention program and the potential molecular mechanisms by which exercise therapy improves sleep disorders. Shortcomings in current research and suggestions are presented, providing a reference for future in-depth studies on exercise interventions for sleep disorders.

Pathways of sleep disturbances in juvenile idiopathic arthritis and recommendations for clinical management approaches: A critical review

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease affecting young people. It has a profound impact on their physical, mental and social lives, leading to long-term disability. With the growing awareness of the importance of sleep in all areas of functioning in young people, an emerging literature has drawn attention to the role of sleep in the pathogenesis of JIA. Sleep disturbances in children and adolescents with JIA arise from a wide range of symptoms and pathways, leading to a vicious cycle that exacerbates subclinical inflammation, symptoms and disease progression. Putative factors contributing to sleep disturbances include chronic inflammation, JIA-associated sleep disorders, JIA symptoms (e.g. pain), psychological comorbidities and potential circadian disruption, which may be exacerbated by the transition to adolescence. Here, we review these pathways and advocate key strategies and alternatives for sleep management in young people with JIA in clinical settings. We identify gaps in knowledge and suggest future directions to improve our understanding of JIA sleep disorders, including clinical trials investigating potential strategies to improve sleep health in this young population.

Acute and long-term sleep measurements produce opposing results on sleep quality in 8 and 12 hour shift patterns in law enforcement officers

The occupational demands of law enforcement increase the risk of poor-quality sleep, putting officers at risk of adverse physical and mental health. This cross-sectional study aimed to characterise sleep quality in day workers, 8 and 12 h rotating shift pattern workers. One hundred eighty-six officers volunteered for the study (37 female, age: 41 ± 7). Sleep quality was assessed using the Pittsburgh sleep quality index, actigraphy and the Leeds sleep evaluation questionnaire. The maximal aerobic capacity (VO2max ) was measured on a treadmill via breath-by-breath analysis. There was a 70% overall prevalence of poor sleepers based on Pittsburgh sleep quality index scores, where 8 h shifts exhibited the worst prevalence (92%, p = 0.029), however, there was no difference between age, gender, or role. In contrast, 12 h shifts exhibited the poorest short-term measures, including awakening from sleep (p = 0.039) and behaviour following wakefulness (p = 0.033) from subjective measures, and poorer total sleep time (p = 0.024) and sleep efficiency (p = 0.024) from the actigraphy. High VO2max predicted poorer wake after sleep onset (Rsq = 0.07, p = 0.05) and poorer sleep latency (p = 0.028). There was no relationship between the Pittsburgh sleep quality index scores and any of the short-term measures. The prevalence of poor sleepers in this cohort was substantially higher than in the general population, regardless of shift pattern. The results obtained from the long- and short-term measures of sleep quality yielded opposing results, where long-term perceptions favoured the 12 h pattern, but short-term subjective and objective measures both favoured the 8 h pattern.

Effects of High-Intensity Interval Training on Melatonin Function and Cellular Lymphocyte Apoptosis in Sedentary Middle-Aged Men

Background: Physical performance increased by controlled interventions of high-intensity intermittent training (HIIT); however, little is known about their influence as anti-aging and antioxidant effects, or their role in mitochondrial biogenesis. Purpose: This study aimed to determine the effects of HIIT for 12 weeks on melatonin function, lymphocyte cell apoptosis, oxidative stress on aging, and physical performance. Methods: Eighty healthy male subjects aged 18-65 years randomly participated in a HIIT-exercise training program for 12 weeks. Anthropometric analysis, cardiovascular fitness, total antioxidant capacity (TAC), lymphocyte count and apoptosis, and serum melatonin and cytochrome c oxidase (COX), were estimated for all subjects before and after HIIT-exercise training. HIIT training was performed in subjects for 12 weeks. Results: Data analysis showed a significant increase in the expression levels of the melatonin hormone (11.2 ± 2.3, p < 0.001), TAC (48.7 ± 7.1, p < 0.002), COX (3.7 ± 0.75, p < 0.001), and a higher percentage of lymphocyte apoptosis (5.2 ± 0.31, p < 0.003). In addition, there was an improvement in fitness scores (W; 196.5 ± 4.6, VO₂max; 58.9 ± 2.5, p < 0.001), adiposity markers (p < 0.001); BMI, WHtR, and glycemic control parameters (p < 0.01); FG, HbA1c (%), FI, and serum C-peptide were significantly improved following HIIT intervention. Both melatonin and lymphocyte apoptosis significantly correlated with the studied parameters, especially TAC and COX. Furthermore, the correlation of lymphocyte apoptosis with longer exercise duration was significantly associated with increased serum melatonin following exercise training. This association supports the mechanistic role of melatonin in promoting lymphocyte apoptosis either via the extrinsic mediator pathway or via inhibition of lymphocyte division in the thymus and lymph nodes. Additionally, the correlation between melatonin, lymphocyte apoptosis, TAC, and COX activities significantly supports their role in enhancing physical performance. Conclusions: The main findings of this study were that HIIT exercise training for 12 weeks significantly improved adiposity markers, glycemic control parameters, and physical performance of sedentary older adult men. In addition, melatonin secretion, % of lymphocyte apoptosis, COX activities, and TAC as biological aging markers were significantly increased following HIIT exercise training interventions for 12 weeks. The use of HIIT exercise was effective in improving biological aging, which is adequate for supporting chronological age, especially regarding aging problems. However, subsequent studies are required with long-term follow-up to consider HIIT as a modulator for several cardiometabolic health problems in older individuals with obesity.

Metabolic Health, Mitochondrial Fitness, Physical Activity, and Cancer

Cancer continues to be a significant global health issue. Traditional genetic-based approaches to understanding and treating cancer have had limited success. Researchers are increasingly exploring the impact of the environment, specifically inflammation and metabolism, on cancer development. Examining the role of mitochondria in this context is crucial for understanding the connections between metabolic health, physical activity, and cancer. This study aimed to review the literature on this topic through a comprehensive narrative review of various databases including MedLine (PubMed), Cochrane (Wiley), Embase, PsychINFO, and CinAhl. The review highlighted the importance of mitochondrial function in overall health and in regulating key events in cancer development, such as apoptosis. The concept of "mitochondrial fitness" emphasizes the crucial role of mitochondria in cell metabolism, particularly their oxidative functions, and how proper function can prevent replication errors and regulate apoptosis. Engaging in high-energy-demanding movement, such as exercise, is a powerful intervention for improving mitochondrial function and increasing resistance to environmental stressors. These findings support the significance of considering the role of the environment, specifically inflammation and metabolism, in cancer development and treatment. Further research is required to fully understand the mechanisms by which physical activity improves mitochondrial function and potentially reduces the risk of cancer.

Physical Activity, Seasonal Sensitivity and Psychological Well-Being of People of Different Age Groups Living in Extreme Environments

Physical activity can prevent many organic and mental pathologies. For people living in extreme southern high-latitude environments, weather conditions can affect these activities, altering their psychological well-being and favoring the prevalence of seasonal sensitivity (SS). This study aims to determine the relationships between the practice of physical activity, seasonal sensitivity and well-being in people living in high southern latitudes. A cross-sectional study was conducted, using the Seasonal Pattern Assessment Questionnaire (SPAQ), applying a psychological well-being scale, and determining sports practice according to the recommendations of the World Health Organization (WHO) for the 370 male (n = 209; 55%) and female (n = 173; 45%) participants. The main results indicated that 194 people (52 ± 7.7 years) reported physical activity. High-intensity physical activity practitioners recorded a significantly lower proportion of SS. In terms of psychological well-being, an adverse effect was found between the Seasonal Score Index (SSI) and five subcategories of the Ryff well-being scale. In conclusion, those who perform high-intensity physical activity have a lower SS, and those who have a higher SS have a lower psychological well-being.

Intraday adaptation to extreme temperatures in outdoor activity

Linkages between climate and human activity are often calibrated at daily or monthly resolutions, which lacks the granularity to observe intraday adaptation behaviors. Ignoring this adaptation margin could mischaracterize the health consequences of future climate change. Here, we construct an hourly outdoor leisure activity database using billions of cell phone location requests in 10,499 parks in 2017 all over China to investigate the within-day outdoor activity rhythm. We find that hourly temperatures above 30 °C and 35 °C depress outdoor leisure activities by 5% (95% confidence interval, CI 3-7%) and by 13% (95% CI 10-16%) respectively. This activity-depressing effect is larger than previous daily or monthly studies due to intraday activity substitution from noon and afternoon to morning and evening. Intraday adaptation is larger for locations and dates with time flexibility, for individuals more frequently exposed to heat, and for parks situated in urban areas. Such within-day adaptation substantially reduces heat exposure, yet it also delays the active time at night by about half an hour, with potential side effect on sleep quality. Combining empirical estimates with outputs from downscaled climate models, we show that unmitigated climate change will generate sizable activity-depressing and activity-delaying effects in summer when projected on an hourly resolution. Our findings call for more attention in leveraging real-time activity data to understand intraday adaptation behaviors and their associated health consequences in climate change research.

Melatonin Inhibits hIAPP Oligomerization by Preventing β-Sheet and Hydrogen Bond Formation of the Amyloidogenic Region Revealed by Replica-Exchange Molecular Dynamics Simulation

The pathogenesis of type 2 diabetes (T2D) is highly related to the abnormal self-assembly of the human islet amyloid polypeptide (hIAPP) into amyloid aggregates. To inhibit hIAPP aggregation is considered a promising therapeutic strategy for T2D treatment. Melatonin (Mel) was reported to effectively impede the accumulation of hIAPP aggregates and dissolve preformed fibrils. However, the underlying mechanism at the atomic level remains elusive. Here, we performed replica-exchange molecular dynamics (REMD) simulations to investigate the inhibitory effect of Mel on hIAPP oligomerization by using hIAPP20–29 octamer as templates. The conformational ensemble shows that Mel molecules can significantly prevent the β-sheet and backbone hydrogen bond formation of hIAPP20–29 octamer and remodel hIAPP oligomers and transform them into less compact conformations with more disordered contents. The interaction analysis shows that the binding behavior of Mel is dominated by hydrogen bonding with a peptide backbone and strengthened by aromatic stacking and CH–π interactions with peptide sidechains. The strong hIAPP–Mel interaction disrupts the hIAPP20–29 association, which is supposed to inhibit amyloid aggregation and cytotoxicity. We also performed conventional MD simulations to investigate the influence and binding affinity of Mel on the preformed hIAPP1–37 fibrillar octamer. Mel was found to preferentially bind to the amyloidogenic region hIAPP20–29, whereas it has a slight influence on the structural stability of the preformed fibrils. Our findings illustrate a possible pathway by which Mel alleviates diabetes symptoms from the perspective of Mel inhibiting amyloid deposits. This work reveals the inhibitory mechanism of Mel against hIAPP20–29 oligomerization, which provides useful clues for the development of efficient anti-amyloid agents.

Physical activity and sleep behaviour in women carrying BRCA1/2 mutations

The aim of the present study is to explore the potential association between sleep quality and physical activity (PA) in women carriers of BRCA1/2 mutations. 63 women completed the Pittsburgh Sleep Quality Index (PSQI) and Godin Shepard Leisure-Time Physical Activity Questionnaire (GSL-TPAQ) and were included in the present cross-sectional analysis. Globally, women showed a PSQI score of 7.0 ± 3.6 and a GSL-TPAQ score of 22.8 ± 18.3. Good sleepers (PSQI score ≤ 5) showed significantly higher PA levels compared to bad sleepers (PSQI score > 5). Women in the higher tertile of GSL-TPAQ total score (≥ 27 METs/week) have a prevalence ratio (PR) of being a good sleeper of 2.85 (1.25-6.52, 95% confidence intervals) compared to women in the lower tertile (≤ 11 METs/week). These results were consistent in BRCA1 and BRCA2 women. Considering each single question of PA intensity, the PR of being a good sleeper by unit of increase of MET/week was higher and significant in women engaged in strenuous and moderate intensity PA. These results suggests a direct association between PA and sleep quality in women carriers of BRCA mutations.

Gene Expression Profile Associated with Asmt Knockout-Induced Depression-Like Behaviors and Exercise Effects in Mouse Hypothalamus

Sleep disorder caused by abnormal circadian rhythm is one of the main symptoms and risk factors of depression. As a known hormone regulating circadian rhythms, melatonin (MT) is also namely N-acetyl-5-methoxytryptamine. N-acetylserotonin methyltransferase (Asmt) is the key rate-limiting enzyme of MT synthesis and has been reportedly associated with depression. Although 50–90% of patients with depression have sleep disorders, there are no effective treatment ways in the clinic. Exercise can regulate circadian rhythm and play an important role in depression treatment. In the present study, we showed that Asmt knockout induced depression-like behaviors, which were ameliorated by swimming exercise. Moreover, swimming exercise increased serum levels of MT and 5-hydroxytryptamine (5-HT) in Asmt knockout mice. In addition, the microarray data identified 10 differentially expressed genes (DEGs) in KO mice compared with WT mice and 29 DEGs in KO mice after swimming exercise. Among the DEGs, the direction and magnitude of change in epidermal growth factor receptor pathway substrate 8-like 1 (Eps8l1) and phospholipase C-β 2 (Plcb2) were confirmed by qRT-PCR partly. Subsequent bioinformatic analysis showed that these DEGs were enriched significantly in the p53 signaling pathway, long-term depression and estrogen signaling pathway. In the protein–protein interaction (PPI) networks, membrane palmitoylated protein 1 (Mpp1) and p53-induced death domain protein 1 (Pidd1) were hub genes to participate in the pathological mechanisms of depression and exercise intervention. These findings may provide new targets for the treatment of depression.

Melatonin Rhythm and Its Relation to Sleep and Circadian Parameters in Children and Adolescents With Autism Spectrum Disorder

Introduction

Sleep problems are prevalent among individuals with autism spectrum disorder (ASD), and a role has been attributed to melatonin in this multifactorial comorbidity.

Methods

A cross-sectional study was conducted on 41 autistic children and adolescents (9.9 ± 3.02) and 24 children and adolescents with a normal intellectual function (8.42 ± 2.43) were used as controls. Subjects were matched for sex, body mass index, and pubertal stage, and all were drug-naive. Circadian and sleep parameters were studied using an ambulatory circadian monitoring (ACM) device, and saliva samples were collected around the onset of sleep to determine dim light melatonin onset (DLMO).

Results

Prepubertal individuals with ASD presented later DLMO and an earlier decline in melatonin during adolescence. A relationship was found between melatonin and both sleep and circadian parameters. Participants and controls with later DLMOs were more likely to have delayed sleep onset times. In the ASD group, subjects with the later daytime midpoint of temperature had a later DLMO. Later melatonin peak time and DLMO time were related to lower general motor activity and lower stability of its rhythms.

Conclusion

The melatonin secretion pattern was different in individuals with ASD, and it showed a relationship with sleep and circadian parameters. Alterations in DLMO have not been previously reported in ASD with the exception of more variable DLMO timing; however, high variability in the study design and sample characteristics prevents direct comparison. The ACM device enabled the measurement of circadian rhythm, a scarcely described parameter in autistic children. When studied in combination with other measures such as melatonin, ACM can offer further knowledge on sleep problems in ASD.

The Molecular Mechanism of Aerobic Exercise Improving Vascular Remodeling in Hypertension

The treatment and prevention of hypertension has been a worldwide medical challenge. The key pathological hallmark of hypertension is altered arterial vascular structure and function, i.e., increased peripheral vascular resistance due to vascular remodeling. The aim of this review is to elucidate the molecular mechanisms of vascular remodeling in hypertension and the protective mechanisms of aerobic exercise against vascular remodeling during the pathological process of hypertension. The main focus is on the mechanisms of oxidative stress and inflammation in the pathological condition of hypertension and vascular phenotypic transformation induced by the trilaminar structure of vascular endothelial cells, smooth muscle cells and extracellular matrix, and the peripheral adipose layer of the vasculature. To further explore the possible mechanisms by which aerobic exercise ameliorates vascular remodeling in the pathological process of hypertension through anti-proliferative, anti-inflammatory, antioxidant and thus inhibiting vascular phenotypic transformation. It provides a new perspective to reveal the intervention targets of vascular remodeling for the prevention and treatment of hypertension and its complications.

Effects of exercise on sleep, melatonin level, and behavioral functioning in children with autism

LAY ABSTRACT

This study examined the impact of physical exercise on sleep and behavioral functioning in children (aged 8-12 years) with autism spectrum disorders. It also investigated whether exercise would alter endogenous melatonin level among the population. Participants were divided into two groups: exercise group (12-week, 30-min morning jogging intervention) and a control group (i.e. did not receive any physical exercise intervention during the study period). Significant improvements on sleep and behavioral functioning were found in the exercise group, but not in the control group Moreover, a significant increase in melatonin level was also shown in the exercise group. Findings of this study reconfirmed the sleep and behavioral benefits of exercise in children with autism spectrum disorder. Melatonin-mediated mechanism should be further explored to develop an effective treatment intervention.

The Effect of Daytime Ingestion of Melatonin on Thyroid Hormones Responses to Acute Submaximal Exercise in Healthy Active Males: A Pilot Study

It is well known that exercise increases the activity of thyroid glands and raises the blood level of melatonin. The increase of melatonin during exercise may be linked to a rise in thyroid-stimulating hormone (TSH). No previous study has investigated the combined effects of melatonin ingestion and acute submaximal exercise on thyroid hormones’ responses. The purpose of this pilot study was to explore the effects of daytime ingestion of melatonin on thyroid hormones’ responses to acute submaximal exercise. After 50 min of either melatonin (6 mg) or placebo ingestion, eight physical education students (mean ± standard deviation of age: 22 ± 1 years) were asked to run for 45 min at 60% of their maximum aerobic speed. Free thyroxine (fT4) and TSH were measured in plasma samples before and immediately after exercise. After submaximal exercise, TSH increased by 54% in both placebo and melatonin conditions. There was no significant (Condition × Exercise) interaction, and no significant condition effect for TSH. The fT4 remained unchanged before/after submaximal exercise in both placebo [15.2 (1.9) and 15.0 (1.6) pmol/L, respectively, p > .05], and melatonin [16.7 (2.7) and 16.3 (2.7) pmol/L, respectively, p > .05] conditions. There was no significant (Condition × Exercise) interaction, no significant exercise effect, and no significant condition effect for fT4. To conclude, acute melatonin ingestion did not affect thyroid hormones’ responses to submaximal exercise.

Mechanisms of melatonin binding and destabilizing the protofilament and filament of tau R3-R4 domains revealed by molecular dynamics simulation

The accumulation of β-amyloid (Aβ) and tau protein is considered to be an important pathological characteristic of Alzheimer's disease (AD). Failure of medicine targeting Aβ has drawn more attention to the influence of tau protein and its fibrillization on neurodegeneration. Increasing evidence shows that melatonin (Mel) can effectively inhibit the formation of tau fibrils and disassemble preformed tau fibrils. However, the underlying mechanism is poorly understood. In this work, we investigated the kinetics of melatonin binding and destabilizing the tetrameric protofilament and octameric filament of tau R3-R4 domains by performing microsecond all-atom molecular dynamics simulations. Our results show that Mel is able to disrupt the C-shaped structure of the tau protofilament and filament, and destabilizes the association between N- and C-termini. Mel predominantly binds to β1 and β6-β8 regions and favors contact with the elongation surface, which is dominantly driven by hydrogen bonding interactions and facilitated by other interactions. The strong π-π stacking interaction of Mel with Y310 impedes the intramolecular CH-π interaction between I308 and Y310, and the cation-π interaction of Mel with R379 interferes with the formation of the D348-R379 salt bridge. Moreover, Mel occupies the protofilament surface in the tetrameric protofilament and prevents the formation of intermolecular hydrogen bonds between residues K331 and Q336 in the octameric filament. Our work provides molecular insights into Mel hindering tau fibrillization or destabilizing the protofilament and filament, and the revealed inhibitory mechanisms provide useful clues for the design of efficient anti-amyloid agents.

Melatonin Enhances the Mitochondrial Functionality of Brown Adipose Tissue in Obese-Diabetic Rats

Developing novel drugs/targets remains a major effort toward controlling obesity-related type 2 diabetes (diabesity). Melatonin controls obesity and improves glucose homeostasis in rodents, mainly via the thermogenic effects of increasing the amount of brown adipose tissue (BAT) and increases in mitochondrial mass, amount of UCP1 protein, and thermogenic capacity. Importantly, mitochondria are widely known as a therapeutic target of melatonin; however, direct evidence of melatonin on the function of mitochondria from BAT and the mechanistic pathways underlying these effects remains lacking. This study investigated the effects of melatonin on mitochondrial functions in BAT of Zücker diabetic fatty (ZDF) rats, which are considered a model of obesity-related type 2 diabetes mellitus (T2DM). At five weeks of age, Zücker lean (ZL) and ZDF rats were subdivided into two groups, consisting of control and treated with oral melatonin for six weeks. Mitochondria were isolated from BAT of animals from both groups, using subcellular fractionation techniques, followed by measurement of several mitochondrial parameters, including respiratory control ratio (RCR), phosphorylation coefficient (ADP/O ratio), ATP production, level of mitochondrial nitrites, superoxide dismutase activity, and alteration in the mitochondrial permeability transition pore (mPTP). Interestingly, melatonin increased RCR in mitochondria from brown fat of both ZL and ZDF rats through the reduction of the proton leak component of respiration (state 4). In addition, melatonin improved the ADP/O ratio in obese rats and augmented ATP production in lean rats. Further, melatonin reduced mitochondrial nitrosative and oxidative status by decreasing nitrite levels and increasing superoxide dismutase activity in both groups, as well as inhibited mPTP in mitochondria isolated from brown fat. Taken together, the present data revealed that chronic oral administration of melatonin improved mitochondrial respiration in brown adipocytes, while decreasing oxidative and nitrosative stress and susceptibility of adipocytes to apoptosis in ZDF rats, suggesting a beneficial use in the treatment of diabesity. Further research regarding the molecular mechanisms underlying the effects of melatonin on diabesity is warranted.

Exercise-induced oxidative stress and melatonin supplementation: current evidence

Melatonin possesses the indoleamine structure and exerts antioxidant and anti-inflammatory actions and other physiological properties. Physical exercise can influence secretion of melatonin. Melatonin is used as a natural supplement among athletes to regulate sleep cycles and protect muscles against oxidative damage. Despite decades of research, there is still a lack of a comprehensive and critical review on melatonin supplementation and physical activity relationship. The aim of this literature review is to examine the antioxidant, anti-inflammatory and other biological functions played by melatonin with reference to the effect of physical exercise on melatonin secretion and the effect of this compound supplementation on exercise-induced oxidative stress in athletes. Evidence shows that intense exercises disturb antioxidant status of competitive athletes, whereas supplementation with melatonin strengthens antioxidant status in trained athletes in various sports as the compound showed high potency in reduction of the oxidative stress and inflammation markers generated during intense and prolonged exercise.

Biological Responses to Short-Term Maximal Exercise in Male Police Officers

The specifics of short-term physical exercise are similar to the immediate reaction demands placed on police officers. Identifying the physiological predisposition to short-term high-intensity exercise in male law enforcement officers will assist in understanding their metabolism and make a significant contribution to a much more personal and individualized workout program. This will improve physical fitness of individual officers, improving their preparedness for such times of emergency. This cross-sectional study was conducted to investigate the responses of hematological (erythrocytes, hemoglobin, hematocrit, leucocytes, monocytes, neutrophils, lymphocytes), hormonal (testosterone, cortisol, melatonin), biochemical (glucose, uric-acid, lactate, creatine-phosphokinase) data to short-term maximal exercise in male police officers (n = 20). Blood samples were collected before- and after- the running-based anaerobic sprint test (RAST), and biological values were corrected for fluid shifts. Data were mean ± standard deviation of differences (= after minus before RAST). After the RAST, values of cortisol, lactate, neutrophils, lymphocytes, and monocytes increased significantly by 7.01 ± 37.36 mmol/l, 7.55 ± 1.67 mmol/l, 0.17 ± 0.26 103/µl, 0.61 ± 0.28 103/µl, and 0.10 ± 0.13 103/µl, respectively. After the RAST, values of melatonin, uric-acid, creatine-phosphokinase, hemoglobin, and hematocrit decreased significantly by -13.24 ± 4.60 pg/ml, -13.28 ± 14.35 µmol/l, -10.23 ± 10.13 IU/l, -2.01 ± 0.81 g/dl, and -4.46 ± 0.59%, respectively. Biological data of male police officers were affected by sprint test. Understanding changes in biological data following short-term maximal exercise can further assist in a better understanding of anaerobic metabolism, which will be helpful to find available methods for coaches to quantify training loads.

Quality of life, physical activity and burnout syndrome during online learning period in Brazilian university students during the COVID-19 pandemic: a cluster analysis

The COVID-19 pandemic caused several changes in the teaching-learning process, as it abruptly replaced the conventional classes into online classes despite social distancing requirements. Such changes may be associated with several mental health problems and negatively affect the quality of life and academic performance of university students. We performed a cluster analysis in a large sample of Brazilian undergraduate students, considering sociodemographic data, physical activity frequency, study areas, Burnout Syndrome (BS), Quality of Life (QoL) and perception of online learning (OL) during COVID-19 pandemic. Seven hundred and three students (between 17 and 62 years, from 67 higher education institutions) participated in the study. We identified three different profiles of students regarding psychological aspects and OL perception. The first profile, called as the 'Low QoL' group was composed of younger students, mainly females, with higher frequency of psychological disorders (as evidenced by the self-report of depression and/or anxiety), in addition to higher Burnout scores, lower QoL and worse OL perception. The second profile called 'Intermediate QoL' comprised participants with an average age of 45 years, with a greater number of men, married, with kids and working in addition to studying. They presented better OL scores than the 'Low QoL' group. The third profile called 'Better QoL' comprised students with higher scores in all domains of QoL and better OL perception, with greater frequency of physical activity and lower BS scores. Students from Health courses showed higher scores for general QoL, and also for the psychological and environmental domains in relation to the other areas. Besides, students of the Exact Sciences courses showed higher scores on all OL perception items in comparison to the other courses. Our results provide insights regarding the mental health profile of undergraduate students, allowing educational managers to outline specific coping strategies to assist students during the pandemic.

Investigation of the effect of training on serotonin, melatonin and hematologic parameters in adolescent basketball players

OBJECTIVES

Exercise can improve both health and mood. Some beneficial effects of exercise are attributed to endocrine status. This study aims to evaluate the effect of eight weeks of basketball training on melatonin, serotonin, and hematologic parameters in basketball players.

METHODS

The experimental group was selected form 34 healthy young boys, aged between 13 and 16 years old. The participants were randomly assigned to the control group (n=17) and the exercise group (n=17). The exercise program consisted of 2 h/day aerobic activity of basketball training in 5 days a week for 8 weeks. Venous blood was taken on the day before experiment (pre-exercise) and on the day following the last exercise (post-exercise) and hormone levels were detected by ELISA.

RESULTS

Serotonin and melatonin levels significantly increased in the post-exercise group compared to the other groups (p<0.05). Exercise caused increase in WBC, RBC, HCT and Hb levels (p<0.05) while did not alter PLT, MCH, and PCT levels (p>0.05). This study indicates that an eight weeks-long regular aerobic exercise increased melatonin and serotonin levels, and also altered some hematological parameters.

CONCLUSIONS

In conclusion, it is believed that improvement in levels of serotonin, melatonin, and hematological parameters after eight weeks of regular basketball training in basketball players could be attributed to beneficial effects of exercise. Investigation in other branches of sports and in different gender and age groups would make contribution into exercise physiology and training science.

Neurochemical and Cognitive Beneficial Effects of Moderate Physical Activity and Catechin in Aged Rats

A healthy aging process is a requirement for good life quality. A relationship between physical activity, the consumption of antioxidants and brain health has been stablished via the activation of pathways that reduce the harmful effects of oxidative stress, by inducing enzymes such as SIRT1, which is a protector of brain function. We analyzed the cognitive and neurochemical effects of applying physical exercise in elderly rats, alone or in combination with the antioxidant catechin. Several tests of spatial and episodic memory and motor coordination were evaluated. In addition, brain monoaminergic neurotransmitters and SIRT1 protein levels were assessed in the brains of the same rats. The results show that physical activity by itself improved age-related memory and learning deficits, correlating with the restoration of brain monoaminergic neurotransmitters and SIRT1 protein levels in the hippocampus. The administration of the antioxidant catechin along with the exercise program enhanced further the monoaminergic pathways, but not the other parameters studied. These results agree with previous reports revealing a neuroprotective effect of physical activity, probably based on its ability to improve the redox status of the brain, demonstrating that exercise at an advanced age, combined with the consumption of antioxidants, could produce favorable effects in terms of brain health.

Melatonin supplementation improves psychomotor and physical performance in collegiate student-athletes following a sleep deprivation night

Several studies report sleep deprivation negatively impacts post-cognitive and physical performance, and other functions. Recent findings indicate ingestion of melatonin prior to exercise enhances tolerance to training and improves competition. We investigated the effects of melatonin supplementation on psychomotor performance and selected physical fitness measures of collegiate student-athletes following 4 h and 24 h of sleep deprivation. The study employed a repeated-measures, double-blind, randomized controlled protocol with posttest control group design with six conditions [3 sleep conditions (without sleep deprivation, 4 h sleep deprivation (4SD) and 24 h sleep deprivation (24SD)) × 2 supplementation conditions (melatonin and placebo)]. Ten trained male collegiate student-athletes (mean ± SD; age: 20 ± 2 y) attended the laboratory on six occasions with 72 h between successive visits. Placebo or 6 mg of melatonin were administered orally in capsules 30 min before the tests of: static and dynamic balance, reaction time, and anaerobic power. Also, blood lactate was measured before and 3 min after the anaerobic power exercise. During the placebo session, the results indicated that 4SD and 24SD had negative effect on the measured parameters, with higher impacts of the 24SD condition. Compared to placebo and during both 4SD and 24SD conditions, melatonin had a positive effect on static and dynamic balance, anaerobic power, blood lactic acid, and reaction time (p < .05). However, 6 mg melatonin ingestion had no significant effect on all dependent variables in collegiate student-athletes after the night without a sleep deprivation (p > .05). In conclusion, 6 mg of melatonin may be used by student-athletes to improve balance and psychomotor and physical performances after 4 h or 24 h of sleep deprivation.

Biological Rhythm and Chronotype: New Perspectives in Health

The circadian rhythm plays a fundamental role in regulating biological functions, including sleep–wake preference, body temperature, hormonal secretion, food intake, and cognitive and physical performance. Alterations in circadian rhythm can lead to chronic disease and impaired sleep. The circadian rhythmicity in human beings is represented by a complex phenotype. Indeed, over a 24-h period, a person’s preferred time to be more active or to sleep can be expressed in the concept of morningness–eveningness. Three chronotypes are distinguished: Morning, Neither, and Evening-types. Interindividual differences in chronotypes need to be considered to reduce the negative effects of circadian disruptions on health. In the present review, we examine the bi-directional influences of the rest–activity circadian rhythm and sleep–wake cycle in chronic pathologies and disorders. We analyze the concept and the main characteristics of the three chronotypes.

Serotonin and Melatonin Show Different Modes of Action on Aβ42 Protofibril Destabilization

Alzheimer's disease (AD) is associated with the aberrant self-assembly of amyloid-β (Aβ) protein into fibrillar deposits. The disaggregation of Aβ fibril is believed as one of the major therapeutic strategies for treating AD. Previous experimental studies reported that serotonin (Ser), one of the indoleamine neurotransmitters, and its derivative melatonin (Mel) are able to disassemble preformed Aβ fibrils. However, the fibril-disruption mechanisms are unclear. As the first step to understand the underlying mechanism, we investigated the interactions of Ser and Mel molecules with the LS-shaped Aβ₄₂ protofibril by performing a total of nine individual 500 ns all-atom molecular dynamics (MD) simulations. The simulations demonstrate that both Ser and Mel molecules disrupt the local β-sheet structure, destroy the salt bridges between K28 side chain and A42 COO^-, and consequently destabilize the global structure of Aβ₄₂ protofibril. The Mel molecule exhibits a greater binding capacity than the Ser molecule. Intriguingly, we find that Ser and Mel molecules destabilize Aβ₄₂ protofibril through different modes of action. Ser preferentially binds with the aromatic residues in the N-terminal region through π-π stacking interactions, while Mel binds not only with the N-terminal aromatic residues but also with the C-terminal hydrophobic residues via π-π and hydrophobic interactions. This work reveals the disruptive mechanisms of Aβ₄₂ protofibril by Ser and Mel molecules and provides useful information for designing drug candidates against AD.

Melatonin on hypothyroidism and gonadal development in rats: a review

We evaluated the evidence in research on the effects of melatonin on hypothyroidism and gonadal development. According to the World Health Organization, thyroid disorders due to iodine deficiency affect about 740 million people worldwide. Hypothyroidism is a thyroid dysfunction characterized by hypometabolism of the gland, with reduced or physiologically normal T3 and T4 serum levels, and high TSH level. This disorder occurs mainly in adult women in the reproductive phase, with a prevalence of 2% among the world's female population, with profound repercussions on gestation and fetal formation. During the gestational period, the thyroid is initially stimulated by high concentrations of human chorionic gonadotrophin; thus, maintaining maternal euthyroidism during pregnancy and lactation is fundamental for fetal growth and development. Besides, the hormones produced by this gland are involved in the formation of various organs, such as the skin, brain and gonads. Hypothyroidism is associated with several menstrual abnormalities, anovulation and hyperprolactinemia, resulting in a high rate of abortions, premature births, placental rupture, and weight-related neonatal deficits. In addition, there are studies showing that hypothyroidism can affect ovarian morphology (number of ovarian follicles) and testicular morphology (changes in the testicular-lumen epithelium). Melatonin is a hormone known to modulate the estrous cycle and pregnancy, and studies show that the exogenous application of melatonin increased T4 levels in female rats and controlled the decrease in T3 serum levels, reverting the sigs of hypothyroidism.

A Public Dataset of 24-h Multi-Levels Psycho-Physiological Responses in Young Healthy Adults

Wearable devices now make it possible to record large quantities of physiological data, which can be used to obtain a clearer view of a person’s health status and behavior. However, to the best of our knowledge, there are no open datasets in the literature that provide psycho-physiological data. The Multilevel Monitoring of Activity and Sleep in Healthy people (MMASH) dataset presented in this paper provides 24 h of continuous psycho-physiological data, that is, inter-beat intervals data, heart rate data, wrist accelerometry data, sleep quality index, physical activity (i.e., number of steps per second), psychological characteristics (e.g., anxiety status, stressful events, and emotion declaration), and sleep hormone levels for 22 participants. The MMASH dataset will enable the investigation of possible relationships between the physical and psychological characteristics of people in daily life. Data were validated through different analyses that showed their compatibility with the literature.

Physical exercise and seizure activity

Neuroprotective and antiepileptogenic therapies have been extensively investigated for epilepsy prevention and treatment. This review gives an overview of the promising contribution of the ketogenic diet, a complementary treatment, on the intestinal microbiota to reduce seizure susceptibility. Next, the relevance of physical exercise is extensively addressed as a complementary therapy to reduce seizure susceptibility, and thereby impact beneficially on the epilepsy condition. In this context, particular attention is given to the potential risks and benefits of physical exercise, possible precipitant factors related to exercise and proposed mechanisms by which exercise can reduce seizures, and its antiepileptogenic effects. Finally, this review points to emerging evidence of exercise reducing comorbidities from epilepsy and improving the quality of life of people with epilepsy. Based on evidence from current literature, physical or sport activities represent a potential non-pharmacological intervention that can be integrated with conventional therapy for epilepsy.

Effect of nocturnal melatonin intake on cellular damage and recovery from repeated sprint performance during an intensive training schedule

An optimal recovery between training sessions is of similar if not greater importance as the training content and program of the training, itself. One of the most used strategies for improving recovery is the ingestion of supplements. The present study aimed to evaluate the effect of 5 mg oral melatonin supplementation on the recovery from repeated sprint (RSA) of performance and biochemical responses (i.e. oxidative stress, leukocytosis cellular damage) after an intensive training camp (TC). Twenty soccer players performed an RSA test before and after an intensive six-day TC associated with nocturnal melatonin (n = 10) or placebo (n = 10) ingestion. Resting and post-RSA test blood samples were obtained before and after the TC. Compared to placebo, melatonin intake decreased resting oxidative stress markers (i.e, advanced oxidation protein products), leukocytosis (i.e. white blood cells (WBC), neutrophils (NE)) and biomarkers of cellular damage (i.e. creatine kinase (CK)). It also lowered post-exercise leukocytosis (i.e. WBC, NE, lymphocytes (LY), monocytes (MO)) and biomarkers of cellular damage (i.e. CK, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT)) and raised the activity of the main antioxidant enzymes (i.e. glutathione peroxidase (GPx), glutathione reductase (GR)). In addition, compared to placebo, melatonin reduced the deterioration of the best and total time during the RSA test after the TC. In conclusion, nocturnal melatonin supplementation during an intensive TC alleviated oxidative stress, leukocytosis and cellular damage and improved recovery of RSA performance in soccer players.

Impact of Melatonin on Skeletal Muscle and Exercise

Skeletal muscle disorders are dramatically increasing with human aging with enormous sanitary costs and impact on the quality of life. Preventive and therapeutic tools to limit onset and progression of muscle frailty include nutrition and physical training. Melatonin, the indole produced at nighttime in pineal and extra-pineal sites in mammalians, has recognized anti-aging, anti-inflammatory, and anti-oxidant properties. Mitochondria are the favorite target of melatonin, which maintains them efficiently, scavenging free radicals and reducing oxidative damage. Here, we discuss the most recent evidence of dietary melatonin efficacy in age-related skeletal muscle disorders in cellular, preclinical, and clinical studies. Furthermore, we analyze the emerging impact of melatonin on physical activity. Finally, we consider the newest evidence of the gut-muscle axis and the influence of exercise and probably melatonin on the microbiota. In our opinion, this review reinforces the relevance of melatonin as a safe nutraceutical that limits skeletal muscle frailty and prolongs physical performance.

Effects of walking on sundown syndrome in community-dwelling people with Alzheimer's disease

BACKGROUND

Sundown syndrome is an important care issue for people with dementia (PwD) and for family caregivers. Walking is a safe and simple physical activity for most PwD, yet no research has explored the effects of different long-term walking periods on sundown syndrome.

OBJECTIVES

This study aimed to determine the effects of walking on sundown syndrome, and to identify whether different walking time periods would show different effects on sundown syndrome in community-dwelling people with Alzheimer's disease.

METHODS

A quasi-experimental designed study with repeated measurements was conducted. Sixty PwD were recruited and assigned to either the control group or the morning or afternoon walking group according to their caregiver's preference. The participants in the two walking groups completed an average of 120-min walking per week, accompanied by their caregivers. Forty-six achieved the 6-month intervention. Four measurements were taken, one at the pretest and one at weeks 8, 16 and 24. The Chinese version of the Cohen-Mansfield Agitation Inventory, community form (C-CMAI) was used to assess the severity of the sundown syndrome. The generalised estimating equation (GEE) was applied for the longitudinal data analysis.

RESULTS

There was a significant change across the study period (p = .048) in the morning walking group, indicating that the score for sundown syndrome decreased when PwD walked in the morning. Considering group effects, compared to the control group, the C-CMAI scores significantly decreased after 16 weeks of walking in the afternoon walking group (p = .001) and after 24 weeks in both the morning and afternoon walking groups (p = .001), indicating that after PwD had walked for 16 weeks, sundown syndrome ameliorated in the afternoon group and continually decreased after 24 weeks in both the morning and afternoon groups. However, there was no significant group difference between the morning and afternoon walking groups during the 24-week walking intervention.

CONCLUSIONS

The results indicated that both morning walking and afternoon walking are beneficial for ameliorating the symptoms of sundown syndrome; however, walking in the afternoon may have a faster effect on the symptoms than walking in the morning. Walking is a safe, simple, feasible and effective intervention to benefit individuals with sundown syndrome.

IMPLICATIONS FOR PRACTICE

Regularly walking for 30 min a day, four times a week, is beneficial to alleviate sundown syndrome among PwD living in the community. Either morning or afternoon walking is effective for decreasing sundown syndrome, and the longer the walking time, the greater the impact on sundown syndrome.

Effects of Melatonin on the Body Composition, Physical Performance, and Blood Erythrocyte Indexes of C57Bl/6J Mice Exposed to Continuous Illumination

Male C57Bl/6J mice were exposed to daily 24-h illumination over 14 days and daily intragastrically received melatonin (1 mg/kg) or water (placebo). Controls were kept under standard day/night (14/10 h) conditions. Melatonin prevented the development of anemia in mice exposed to continuous illumination, which was proven by higher blood hemoglobin levels by the end of the experiment in melatonin-treated animals in comparison with the placebo group. Studies by the low-field NMR spectrometry detected lower lean body mass, total body water, and especially, fat content (by ~13%) in animals receiving placebo. Melatonin treatment led to an increase in the lean body mass and total body water on day 7 (in comparison with the placebo group) without affecting fat mass. On day 14 of continuous illumination, lean body mass increased in comparison with the corresponding parameter in the control and placebo groups. Melatonin had no effect on the physical endurance of mice exposed to continuous illumination (assessed by the grid hanging test).

Involvement of plasma miRNAs, muscle miRNAs and mitochondrial miRNAs in the pathophysiology of frailty

Frailty is a geriatric syndrome that leads not only to the loss of physical functions, but also to a generalized decline of the organism and a high risk of disability and dependency. Frailty's detection and management represent important goals for current gerontology. The advance in its rapid diagnosis could play a relevant role in taking measures to reduce the negative consequences it exerts on the body and to take preventive measures. microRNAs are the one of multiple epigenetic biomarkers that reflect functional changes in aged subject. In this review we analyze microRNAs as molecules involved in the control of the pathways leading to the development of frailty. miRNAs can be present in different body fluids, including plasma/serum and saliva, can be associated with organelles like the mitochondria, and can be expressed in tissues. Based on the multifactorial physiopathology of frailty, we analyzed here the microRNAs linked to "inflammaging" (inflamma-miRs), to musculoskeletal health (myomiRs), and microRNAs that can directly or indirectly affect the mitochondria (mitomiRs). Subsequently, we analyze those microRNAs that can be modified by physical exercise. In this review we will analyze the latest experimental studies carried out in animals, cell cultures, and human samples, with the aim to identify gaps in the research and in order to try to dazzle the information about the pathways regulated by each miRNA. Multiple studies revised here suggest that several miRs can be considered as possible markers of frailty, including miR-1, miR-21, miR-34a, miR-146a, miR-185, and miR-206, miR-223, among others. Normalization of miRNAs data and standardization of the protocols used for their measurement to avoid confounding variables influencing the results, are important to use miRNAs as disease biomarkers.

Influence of Exercise Time of Day on Salivary Melatonin Responses

BACKGROUND

Sleep deprivation negatively affects cognition, pain, mood, metabolism, and immunity, which can reduce athletic performance. Melatonin facilitates sleepiness and may be affected by the proximity of exercise to sleep.

PURPOSE

To evaluate the influence of exercise time of day on salivary melatonin (s-melatonin) responses.

METHODS

Twelve regularly exercising men (age 20.75 [0.62] y, height 1.75 [0.04] m, mass 73.63 [10.43] kg, and maximal oxygen consumption 57.72 [6.11] mL/kg/min) participated in a randomized, crossover design. Subjects completed 3 protocols-morning exercise (09:00 h), afternoon exercise (16:00 h), and no exercise (CON)-at least 5 d apart. Exercise sessions consisted of 30 min of steady-state running at 75% of maximal oxygen consumption. Saliva was collected via passive drool at 20:00, 22:00, and 03:00 h following all sessions.

RESULTS

Repeated-measures analysis of variance revealed significant time (P = .001) and condition (P = .026) effects for melatonin. Levels of s-melatonin were significantly increased at 03:00 h compared with 20:00 and 22:00 h for all conditions. Post hoc analyses revealed that s-melatonin at 22:00 h was significantly higher after morning exercise (16.5 [7.5] pg/mL) compared with afternoon exercise (13.7 [6.1] pg/mL) sessions (P = .03), whereas neither exercise condition significantly differed from the control (P > .05).

CONCLUSIONS

It appears that exercising in the afternoon may blunt melatonin secretion compared with morning exercise. If sleep is an issue, morning exercise may be preferable to afternoon exercise.

Protective stabilization of mitochondrial permeability transition and mitochondrial oxidation during mitochondrial Ca2+ stress by melatonin's cascade metabolites C3-OHM and AFMK in RBA1 astrocytes

Cyclic 3-hydroxymelatonin (C3-OHM) and N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) are two major cascade metabolites of melatonin. We previously showed melatonin provides multiple levels of mitochondria-targeted protection beyond as a mitochondrial antioxidant during ionomycin-induced mitochondrial Ca²⁺ (mCa²⁺ ) stress in RBA1 astrocytes. Using noninvasive laser scanning fluorescence coupled time-lapse digital imaging microscopy, this study investigated whether C3-OHM and AFMK also provide mitochondrial levels of protection during ionomycin-induced mCa²⁺ stress in RBA1 astrocytes. Interestingly, precise temporal and spatial dynamic live mitochondrial images revealed that C3-OHM and AFMK prevented specifically mCa²⁺ -mediated mitochondrial reactive oxygen species (mROS) formation and hence mROS-mediated depolarization of mitochondrial membrane potential (△Ψ_m ) and permanent lethal opening of the MPT (p-MPT). The antioxidative effects of AFMK, however, were less potent than that of C3-OHM. Whether C3-OHM and AFMK targeted directly the MPT was investigated under a condition of "oxidation free-Ca²⁺ stress" using a classic antioxidant vitamin E to remove mCa²⁺ -mediated mROS stress and the potential antioxidative effects of C3-OHM and AFMK. Intriguingly, two compounds still effectively postponed "oxidation free-Ca²⁺ stress"-mediated depolarization of △Ψ_m and p-MPT. Measurements using a MPT pore-specific indicator Calcein further identified that C3-OHM and AFMK, rather than inhibiting, stabilized the MPT in its transient protective opening mode (t-MPT), a critical mechanism to reduce overloaded mROS and mCa²⁺ . These multiple layers of mitochondrial protection provided by C3-OHM and AFMK thus crucially allow melatonin to extend its metabolic cascades of mitochondrial protection during mROS- and mCa²⁺ -mediated MPT-associated apoptotic stresses and may provide therapeutic benefits against astrocyte-mediated neurodegeneration in the CNS.

Effect of melatonin ingestion on physical performance, metabolic responses, and recovery after an intermittent training session

Objectives

Fatigue is a limiting factor for sport performance. For this reason, optimal recovery after training is just as critical as the training program itself, if not more. Indeed, there is a need for strategies that can facilitate recovery after training, and one such strategy is the ingestion of supplements like melatonin (MEL). This study aimed to evaluate if MEL intake could improve recovery of athletes after an intermittent training session (ITS).

Methods

Fifteen elite female athletes (17.4 ± 0.4 years, 76.4 ± 5.6 kg, 1.76 ± 0.04 m; mean ± standard deviation) participated in two testing campaigns. During each period, they performed a battery of physical and cognitive tests before and after an ITS, as well as after ingesting MEL (6 mg tablet) or placebo in a randomized design. The ITS comprised the modified agility T-test, squat jump, counter movement jump, maximum standing ball-throw velocity test, maximum jump ball-throw velocity test, and 20-m sprint. Oral temperature (OT) and vigilance were evaluated before and after the ITS. Rating of perceived exertion (RPE), blood lactate [La], and glucose [Gl] were recorded after each ITS.

Results

Short-term performance, recovery of physical performance, and OT were not affected by MEL ingestion after the ITS. Moreover, MEL did not affect cognitive performance or RPE scores after the ITS. However, [La] and [Gl] (p < 0.05 for both) were decreased after MEL ingestion.

Conclusion

MEL has no effect on the recovery of physical performance but may affect glucose utilization and lactate metabolism during the team-handball training session.

From pillow to podium: a review on understanding sleep for elite athletes

Sleep is considered vital to human health and well-being, and is critical to physiological and cognitive functioning. Elite athletes experience high training and competition demands, and are often exposed to various factors, situations, and environments that can cause sleep impairments. Previous research has shown that athletes commonly experience sleep loss in the lead up to and following competition, which could have significant impacts on their preparation, performance, and recovery. In particular, the results from previous research show significant reductions in total sleep time (~1:40 h:min) and significant increases in sleep latency (~45 minutes) following evening competition. Napping is common in both the training and competition setting in athletes; however, research on the effect of napping on physiology and performance is limited. In contrast, research on strategies and interventions to improve sleep are increasing in the athletic population, with sleep hygiene research resulting in significant improvements in key sleep indices. This review investigates the physiological importance of sleep in athletes, current tools to monitor athletes' sleep, the role of sleep for cognitive functioning and athletic performance, the prevalence of sleep disturbances and the potential mechanisms causing sleep disturbances, the role of napping, and different intervention strategies to improve sleep.

Aerobic exercise enhanced endothelium-dependent vasorelaxation in mesenteric arteries in spontaneously hypertensive rats: the role of melatonin

Melatonin, a neuroendocrine hormone synthesized primarily by the pineal gland, provides various cardiovascular benefits. Regular physical activity is an effective non-pharmacological therapy for the prevention and control of hypertension. In the present study, we hypothesized that melatonin plays an important role in the aerobic exercise-induced increase of endothelium-dependent vasorelaxation in the mesenteric arteries (MAs) of spontaneously hypertensive rats (SHRs) in a melatonergic receptor-dependent manner. To test this hypothesis, we evaluated the vascular mechanical and functional properties in normotensive Wistar Kyoto (WKY), SHRs, and SHRs that were trained on a treadmill (SHR-EX) for 8 weeks. Exercise training produced a significant reduction in blood pressure and heart rate in SHR, which was significantly attenuated by the intraperitoneal administration of luzindole, a non-selective melatonin receptor (MT1/MT2) antagonist. Serum melatonin levels in the SHR group were significantly lower than those in the WKY group at 8:00-9:00 and 21:00-22:00, while exercise training reduced this difference. Endothelium-dependent vessel relaxation induced by acetylcholine was significantly blunted in SHR compared with age-matched WKY. Both exercise training and luzindole ameliorated this endothelium-dependent impairment of relaxation in hypertension. Immunohistochemistry and Western blotting showed that the protein expression of the MT2 receptor and eNOS, as well as their colocalization in the endothelial cell layer in SHRs, was significantly decreased; as exercise training suppressed this reduction. These results provide evidence that regular exercise has a beneficial effect on improving endothelium-dependent vasorelaxation in MAs, in which melatonin plays a critical role by acting on MT2 receptors to increase NO production and/or NO bioavailability.

Melatonin ingestion after exhaustive late-evening exercise improves sleep quality and quantity, and short-term performances in teenage athletes

The present study aimed to explore the effects of a single 10-mg dose of melatonin (MEL) administration after exhaustive late-evening exercise on sleep quality and quantity, and short-term physical and cognitive performances in healthy teenagers. Ten male adolescent athletes (mean ± SD, age = 15.4 ± 0.3 years, body-mass = 60.68 ± 5.7 kg, height = 167.9 ± 6.9 cm and BMI = 21.21 ± 2.5) performed two test sessions separated by at least one week. During each session, participants completed the Yo-Yo intermittent-recovery-test level-1 (YYIRT-1) at ~20:00 h. Then, sleep polysomnography was recorded from 22:15 min to 07:00 h, after a double blind randomized order administration of a single 10-mg tablet of MEL (MEL-10 mg) or Placebo (PLA). The following morning, Hooper wellness index was administered and the participants performed the Choice Reaction Time (CRT) test, the Zazzo test and some short-term physical exercises (YYIRT-1, vertical and horizontal Jumps (VJ; HJ), Hand grip strength (HG), and five-jump test (5-JT)). Evening total distance covered in the YYIRT-1 did not change during the two conditions (p > 0.05). Total sleep time (Δ = 24.55 mn; p < 0.001), sleep efficiency (Δ = 4.47%; p < 0.001), stage-3 sleep (N3 sleep) (Δ = 1.73%; p < 0.05) and rapid-eye-movement sleep (Δ = 2.15%; p < 0.001) were significantly higher with MEL in comparison with PLA. Moreover, sleep-onset-latency (Δ = -8.45mn; p < 0.001), total time of nocturnal awakenings after sleep-onset (NA) (Δ = -11 mn; p < 0.001), stage-1 sleep (N1 sleep) (Δ = -1.7%; p < 0.001) and stage-2 sleep (N2 sleep) (Δ = -1.9%; p < 0.05) durations were lower with MEL. The Hooper index showed a better subjective sleep quality, a decrease of the subjective perception of fatigue and a reduced level of muscle soreness with MEL. Moreover, MEL improved speed and performance but not inaccuracy during the Zazzo test. CRT was faster with MEL. Morning YYIRT-1 (Δ = 82 m; p < 0.001) and 5-JT (Δ = 0.08 m; p < 0.05) performances were significantly higher with MEL in comparison with PLA. In contrast, HG, VJ and HJ performances did not change during the two conditions (p > 0.05). The administration of a single dose of MEL-10 mg after strenuous late-evening exercise improved sleep quality and quantity, selective attention, subjective assessment of the general wellness state, and some short-term physical performances the following morning in healthy teenagers.

Melatonin Treatment Reduces Oxidative Damage and Normalizes Plasma Pro-Inflammatory Cytokines in Patients Suffering from Charcot-Marie-Tooth Neuropathy: A Pilot Study in Three Children

Charcot-Marie-Tooth neuropathy (CMT) is a motor and sensory neuropathy comprising a heterogeneous group of inherited diseases. The CMT1A phenotype is predominant in the 70% of CMT patients, with nerve conduction velocity reduction and hypertrophic demyelination. These patients have elevated oxidative stress and chronic inflammation. Currently, there is no effective cure for CMT; herein, we investigated whether melatonin treatment may reduce the inflammatory and oxidative damage in CMT1A patients. Three patients, aged 8–10 years, were treated with melatonin (60 mg at 21:00 h plus 10 mg at 09:00 h), and plasma levels of lipid peroxidation (LPO), nitrites (NOx), IL-1β, IL-2, IL-6, TNF-α, INF-γ, oxidized to reduced glutathione (GSSG/GSH) ratio, and the activities of superoxide dismutase (SOD), glutathione-S transferase (GST), glutathione peroxidase (GPx), and reductase (GRd), were determined in erythrocytes at 3 and 6 months of treatment. Healthy age- and sex-matched subjects were used as controls. The results showed increased activities of SOD, GST, GPx, and GRd in CMT1A patients, which were reduced at 3 and 6 months of treatment. The GSSG/GSH ratio significantly increased in the patients, returning to control values after melatonin treatment. The inflammatory process was confirmed by the elevation of all proinflammatory cytokines measured, which were also normalized by melatonin. LPO and NOx, which also were elevated in the patients, were normalized by melatonin. The results document beneficial effects of the use of melatonin in CMT1A patients to reduce the hyperoxidative and inflammatory condition, which may correlate with a reduction of the degenerative process.

Role of melatonin combined with exercise as a switch-like regulator for circadian behavior in advanced osteoarthritic knee

Here, we show the role of melatonin combined with or without exercise as a determinant of multicellular behavior in osteoarthritis. We address the relationship between the molecular components governing local circadian clock and changes in the osteoarthritic musculoskeletal axis. Melatonin was injected subcutaneously in animals with advanced knee osteoarthritis (OA) for 4 weeks. Concurrently, moderate treadmill exercise was applied for 30 min/day. Morphometric, histological, and gene/protein-level analyses were performed in the cartilage, synovium, bone, and gastrocnemius muscle. Primary cultured chondrocytes repeatedly exposed to TNF-α were used in an in vitro study. The symptoms of OA include gait disturbance, osteophyte formation, and abnormal metabolism of the extracellular matrix (ECM) of the cartilage. Low-level expression of clock genes was accompanied by aberrant changes in cartilage specimens. Nanomolar doses of melatonin restored the expression of clock-controlled genes and corrected the abnormal chondrocyte phenotype. Melatonin combined with or without exercise prevented periarticular muscle damage as well as cartilage degeneration. But prolonged melatonin administration promoted the proteolytic cleavage of RANKL protein in the synovium, leading to severe subchondral bone erosion. These musculoskeletal changes apparently occurred via the regulation of molecular clock components, suggesting a role of melatonin as a switch-like regulator for the OA phenotype.