Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials

Coffee bean processing: Emerging methods and their effects on chemical, biological and sensory properties

Emerging processing methods have been applied in coffee bean processing for improved sensory quality. The processes focus on optimizing the fermentation process of the coffee cherries and beans. This involves various pathways, including the formation of volatiles, flavor precursors and organic acids and the reduction in the concentrations of bioactive compounds. Comprehensive information regarding the effect of these emerging processes on the chemical, biological and sensory properties of the coffee beans is summarized. Emerging processes affected the coffee bean to various degrees depending on the raw material and the method used. The emerging methods promoted the reduction of bioactives such as caffeine and phenolics in coffee beans. Substantial improvement of these processes is needed to obtain coffee beans with improved biological activities. Effort to simplify the methods and optimize the post-fermentation process is crucial for the methods to be easily accessible by the producers and to produce defect-free coffee beans.

Associations between Stress, Anxiety, Depression and Sleep Quality among Healthcare Students

OBJECTIVES

Stress, anxiety, and depression among students have many negative health consequences and may predispose students to poor sleep quality; therefore, this research aimed to investigate the perceived stress, anxiety, and depression and their relation to the level of sleep quality among healthcare students.

METHODS

A cross-sectional study using a validated survey was conducted among Saudi healthcare students from different regions during the period from 26 September 2022 to 30 October 2022. The Pittsburgh Sleep Quality Index (PSQI) was utilized to assess sleep quality. PSPP Statistical Analysis Software version 1.2.0 was used for all statistical analyses.

RESULTS

701 respondents participated in this research; the response rate was 73.8%. About 60% of the study sample was female, and the average age was 20.9 years. 80.3% of students have poor sleep quality; the participants' mean sleeping hours per night was 6.81 ± 1.88 h. About three-quarters of students (72.9%) perceive themselves as stressed. A significant positive correlation was observed between sleep quality and perceived stress (r-value = 0.363), anxiety (r-value = 0.387), and depression (r-value = 0.347). Poor sleep quality was more likely among those with stress than those without stress (AOR = 1.79; 95% CI 1.07, 2.99) and two times more likely among students with cases of anxiety than those without anxiety (AOR = 2.07; 95% CI 1.10, 3.94).

CONCLUSIONS

Our study highlights the high prevalence of poor sleep quality, anxiety, depression, and stress among healthcare students in Saudi Arabia. Students' reported stress, anxiety, and residence region were associated with poor sleep quality. These results imply the necessity of regular screening and appropriate intervention for sleep problems, stressors, and anxiety among healthcare students.

New Pieces for an Old Puzzle: Approaching Parkinson's Disease from Translatable Animal Models, Gut Microbiota Modulation, and Lipidomics

Parkinson's disease (PD) is a severe neurodegenerative disease characterized by disabling motor alterations that are diagnosed at a relatively late stage in its development, and non-motor symptoms, including those affecting the gastrointestinal tract (mainly constipation), which start much earlier than the motor symptoms. Remarkably, current treatments only reduce motor symptoms, not without important drawbacks (relatively low efficiency and impactful side effects). Thus, new approaches are needed to halt PD progression and, possibly, to prevent its development, including new therapeutic strategies that target PD etiopathogeny and new biomarkers. Our aim was to review some of these new approaches. Although PD is complex and heterogeneous, compelling evidence suggests it might have a gastrointestinal origin, at least in a significant number of patients, and findings in recently developed animal models strongly support this hypothesis. Furthermore, the modulation of the gut microbiome, mainly through probiotics, is being tested to improve motor and non-motor symptoms and even to prevent PD. Finally, lipidomics has emerged as a useful tool to identify lipid biomarkers that may help analyze PD progression and treatment efficacy in a personalized manner, although, as of today, it has only scarcely been applied to monitor gut motility, dysbiosis, and probiotic effects in PD. Altogether, these new pieces should be helpful in solving the old puzzle of PD.

A systematic review and meta-analysis of the association between young adults' sleep habits and substance use, with a focus on self-medication behaviours

Young adults (18-30 years) are vulnerable to sleep-wake disturbances and substance use, which are bi-directionally associated. The present work aims to organise the literature that deals with the association between sleep and substance use in young adults, also considering self-medication behaviours. We adopted a framework that accounts for the multidimensionality of sleep and the effect of different substances. We considered sleep disturbances (insomnia symptoms, sleep quality), sleep health dimensions (duration, satisfaction, efficiency, timing, daytime alertness), circadian characteristics (chronotype). Substances were alcohol, caffeine, nicotine, cannabis, others. We included 46 studies. The use of caffeine and nicotine was associated with higher odds of sleep disturbances. No significant effect was detected for sleep duration. In narrative findings, daytime dysfunction was associated with alcohol and caffeine use, and poor sleep satisfaction with nicotine use. Few evidence were available for the other sleep health dimensions. Evening chronotype was associated with alcohol, caffeine, and nicotine use. Few studies focused on cannabis or self-medication. Longitudinal results were inconclusive. We found a distinct pattern of associations between different substances and different sleep outcomes. Further investigation considering the multidimensionality of sleep would create a better understanding of the complex relationship between substance use and sleep health in young adults.

Sleep disorder, Mediterranean diet, and all-cause and cause-specific mortality: a prospective cohort study

BACKGROUND

There is a bidirectional effect between sleep disorders and Mediterranean diet (MED), but the joint effect of MED and sleep disorders on mortality is unclear. The aim of this study was to investigate whether there is a synergistic effect of adherence to MED and sleep disorders on all-cause and cause-specific mortality.

METHODS

The study included 23,212 individuals in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2014. A 9-point evaluation score, alternative Mediterranean diet (aMED) index was used to assess adherence to MED. Sleep disorder and hours of sleep were assessed by structured questionnaires. Cox regression models were used to assess the relationship between sleep disorders, aMED and all-cause mortality, cause-specific mortality (cardiovascular-related death, cancer-related death). The interaction effect of sleep disorders with aMED on mortality was further assessed.

RESULTS

Results showed that participants with lower aMED and presence of sleep disorders had significantly higher risk of all-cause mortality and cardiovascular-related mortality (HR, 2.16, 95% CI, 1.49-3.13, P < 0.0001; HR, 2.68, 95% CI, 1.58-4.54, P = 0.0003). A significant interaction effect was found between aMED and sleep disorders on cardiovascular mortality (p for interaction = 0.033). No significant interaction existed between aMED and sleep disorders on all-cause mortality (p for interaction = 0.184) and cancer-related mortality (p for interaction = 0.955).

CONCLUSIONS

Poorer adherence to MED and sleep disorders synergistically increased long-term all-cause mortality and cardiovascular mortality in NHANES population.

Association between CLOCK Gene Polymorphisms and Insomnia Risk According to Food Groups: A KoGES Longitudinal Study

Food intake could mitigate or exacerbate the risk for insomnia associated with the CLOCK gene. This study investigated the associations between the clock circadian regulator (CLOCK) polymorphisms rs12649507 and rs4580704 and the risk of insomnia, as well as its interactions with food groups. Among 1430 adults, new insomnia cases were identified between 2005 and 2012. Single nucleotide polymorphisms were genotyped, and dietary intake was assessed. Next, Cox proportional hazard models were established. The fruit and meat groups significantly mitigated the risk of insomnia associated with rs12649507 among males (pinteraction = 0.006 in a recessive model; p = 0.010 in a dominant model). In contrast, among females the beverage group significantly increased the risk of insomnia (p = 0.041 in a dominant model). As for rs4580704, among males the fruit and meat groups modified the risk of insomnia (p = 0.006 in a recessive model; p = 0.001 in a dominant model). However, among females, the beverage group exacerbated the risk of insomnia associated with rs4580704 (p = 0.004 in a dominant model). In this longitudinal study, we observed a significantly modified insomnia risk associated with the CLOCK gene depending on food groups. Notably, in a general population the risks were modified according to both the fruit and meat intake among 775 males but exacerbated with beverage intake among 655 females.

The effect of coffee and black tea consumption on sleep bruxism intensity based on polysomnographic examination

Background

Sleep bruxism (SB) is a common behavior that can result in various clinical consequences on human health. Risk factors for SB include among others emotional stress, anxiety, tobacco smoking, and excessive alcohol consumption. Coffee and black tea are among the most commonly consumed beverages worldwide. This study explores the influence of coffee and black tea consumption on bruxism intensity, as observed in polysomnographic examination.

Methods

Polysomnographic examination with simultaneous camera recording was conducted in 106 adult subjects. The results were evaluated according to guidelines set out by the American Academy of Sleep Medicine (AASM). The study group was divided according to habitual stimulant usage, as declared by the participants in a self-reported questionnaire. Four groups were identified: coffee drinkers versus non-drinkers and black tea drinkers versus non-drinkers.

Results

The bruxism episode index (BEI) was increased in coffee-drinkers as opposed to non-drinkers (4.59 ± 3.44 vs. 2.87 ± 1.50, p = 0.011). Sleep fragmentation, measured according to the arousal index, was comparable in coffee drinkers and non-drinkers. Electrolyte and lipid levels were similar in coffee drinkers and non-drinkers. Habitual black tea intake did not affect sleep architecture or bruxism intensity.

Conclusions

The study showed that habitual coffee consumption is a risk factor for the increased intensity of sleep bruxism. Neither coffee nor tea consumption is related to sleep fragmentation in habitual drinkers. Coffee and tea intake does not affect electrolyte and lipid concentrations. Caution should therefore be recommended in drinking coffee in people with sleep bruxism.

Caffeine and sport

Caffeine is a trimethylxanthine found in coffee and several other foods and beverages. Its stimulatory effects make it an interesting strategy to boost performance for athletic populations. Scientific evidence supports its efficacy to improve high-intensity endurance exercise, explosive and high-intensity efforts, resistance exercise, team sports and combat sports, though individual variation in the ergogenic response to caffeine exists. Supplementation can be taken in many forms including dissolved in water, via capsules, coffee, energy drinks and caffeinated gum; ingestion via capsules, dissolved in water or in caffeinated gum appear to be most effective. Variability in the exercise response following caffeine supplementation may be explained by genetic factors or habitual caffeine consumption. Caffeine is an excellent supplement for athletes looking to improve their exercise performance, though some consideration of side-effects and impact on sleep are warranted.

Tracking sleep in the field: sleep quality and sleep behaviours of elite track and field athletes during preparation and competition

Elite athletes are susceptible to inadequate sleep, which may peak during competition and be exacerbated by poor sleep behaviours. This study sought to characterise and compare the sleep quality and sleep behaviours of elite track and field athletes during preparation and major competitions. Forty elite international track and field athletes (50% female, aged 25.1 ± 3.9 years) completed the Athlete Sleep Screening Questionnaire and the Athlete Sleep Behaviour Questionnaire on three separate occasions: during habitual training, during a pre-meet training camp and during a major international competition. Overall, 62.5% of athletes reported at least mild sleep difficulty during competition. Athletes reported higher sleep difficulty and poorer sleep behaviour during major competitions and the pre-meet training camp compared to habitual training (P = .001-.025). No significant differences were observed between the training camp and major competition. Global sleep behaviour scores were underpinned by unique characteristics at each timepoint. Sleep behaviour (R² = .330, P = .017), injury status (R² = .253, P = .003) and major championship experience (R² = .113, P = .034) were associated with sleep difficulty during competition. Sleep quality and behaviours vary according to stage of the track and field season, providing a foundation for targeted intervention.

Clinical and pharmacological correlates of caffeine consumption in subjects with schizophrenia - Data from the FACE-SZ cohort

Caffeine is the most consumed psychoactive substance worldwide. Previous studies suggested higher caffeine consumption in subjects with schizophrenia spectrum disorders (SSD) as well as associations with symptoms, medication and medication side-effects. In a large and well-characterized sample of SSD subjects we explored the association between caffeine consumption and clinical (psychosis related, severity, general health) as well as pharmacological (antipsychotic treatment, sedation potential) variables. Eight hundred four subjects with data on their caffeine (coffee and tea) consumption successively recruited were included in this study. After controlling for potential confounders (demographic variables, smoking) only the negative dimension of psychosis was associated with the amount of caffeine ingested. Less severe negative symptoms were associated with higher caffeine consumption. The effect size of this association was small (partial correlation coefficient = -0.12) but significant.

Special tea products featuring functional components: Health benefits and processing strategies

The functional components in tea confer various potential health benefits to humans. To date, several special tea products featuring functional components (STPFCs) have been successfully developed, such as O-methylated catechin-rich tea, γ-aminobutyric acid-rich tea, low-caffeine tea, and selenium-rich tea products. STPFCs have some unique and enhanced health benefits when compared with conventional tea products, which can meet the specific needs and preferences of different groups and have huge market potential. The processing strategies to improve the health benefits of tea products by regulating the functional component content have been an active area of research in food science. The fresh leaves of some specific tea varieties rich in functional components are used as raw materials, and special processing technologies are employed to prepare STPFCs. Huge progress has been achieved in the research and development of these STPFCs. However, the current status of these STPFCs has not yet been systematically reviewed. Here, studies on STPFCs have been comprehensively reviewed with a focus on their potential health benefits and processing strategies. Additionally, other chemical components with the potential to be developed into special teas and the application of tea functional components in the food industry have been discussed. Finally, suggestions on the promises and challenges for the future study of these STPFCs have been provided. This paper might shed light on the current status of the research and development of these STPFCs. Future studies on STPFCs should focus on screening specific tea varieties, identifying new functional components, evaluating health-promoting effects, improving flavor quality, and elucidating the interactions between functional components.

Sleep physiology, pathophysiology, and sleep hygiene

Despite sleep's fundamental role in maintaining and improving physical and mental health, many people get less than the recommended amount of sleep or suffer from sleeping disorders. This review highlights sleep's instrumental biological functions, various sleep problems, and sleep hygiene and lifestyle interventions that can help improve sleep quality. Quality sleep allows for improved cardiovascular health, mental health, cognition, memory consolidation, immunity, reproductive health, and hormone regulation. Sleep disorders, such as insomnia, sleep apnea, and circadian-rhythm-disorders, or disrupted sleep from lifestyle choices, environmental conditions, or other medical issues can lead to significant morbidity and can contribute to or exacerbate medical and psychiatric conditions. The best treatment for long-term sleep improvement is proper sleep hygiene through behavior and sleep habit modification. Recommendations to improve sleep include achieving 7 to 9 h of sleep, maintaining a consistent sleep/wake schedule, a regular bedtime routine, engaging in regular exercise, and adopting a contemplative practice. In addition, avoiding many substances late in the day can help improve sleep. Caffeine, alcohol, heavy meals, and light exposure later in the day are associated with fragmented poor-quality sleep. These sleep hygiene practices can promote better quality and duration of sleep, with corresponding health benefits.

The Relationship between Sleep Duration and Metabolic Syndrome Severity Scores in Emerging Adults

BACKGROUND

Research suggests sleep duration can influence metabolic systems including glucose homeostasis, blood pressure, hormone regulation, nervous system activity, and total energy expenditure (TEE), all of which are related to cardiometabolic disease risk, even in young adults. The purpose of this study was to examine the relationship between sleep duration and metabolic syndrome severity scores (MSSS) in a sample of emerging adults (18-24 y/o).

METHODS

Data were collected between 2012 and 2021 from the College Health and Nutrition Assessment Survey, an ongoing, cross-sectional study conducted at a midsized northeastern university. Anthropometric, biochemical, and clinical measures were obtained following an overnight fast and used to assess the prevalence of metabolic syndrome (MetS). MetS severity scores (MSSS) were calculated using race- and sex-specific formulas. Sleep duration was calculated from the difference in self-reported bedtime and wake time acquired through an online survey. ANCOVA was used to examine the relationship between sleep duration and MetS severity score while adjusting for covariates (age, sex, BMI, physical activity level, smoking status, alcohol consumption, and academic major).

RESULTS

In the final sample (n = 3816), MetS (≥3 criteria) was present in 3.3% of students, while 15.4% of students presented with ≥2 MetS criteria. Mean MSSS was -0.65 ± 0.56, and the reported sleep duration was 8.2 ± 1.3 h/day. MSSS was higher among low sleepers (<7 h/day) and long sleepers (>9 h/day) compared to the reference sleepers (7-8 h/day) (-0.61 ± 0.02 and -0.63 ± 0.01 vs. -0.7 ± 0.02, respectively, p < 0.01).

CONCLUSIONS

Our findings suggest short (<7 h/day) and long (>9 h/day) sleep durations raise the risk of MetS in a sample of emerging adults. Further research is needed to elucidate the impact of improving sleep habits on future disease risk.

Antioxidant and Antibacterial Properties of a Functional Sports Beverage Formulation

Athletes often consume functional beverages in order to improve performance and reduce oxidative stress caused by high-intensity exercise. The present study aimed to evaluate the antioxidant and antibacterial properties of a functional sports beverage formulation. The beverage's antioxidant effects were assessed on human mesenchymal stem cells (MSCs) by determining thiobarbituric acid reactive substances (TBARS; TBARS levels decreased significantly by 52.67% at 2.0 mg/mL), total antioxidant capacity (TAC; TAC levels increased significantly by 80.82% at 2.0 mg/mL) and reduced glutathione (GSH; GSH levels increased significantly by 24.13% at 2.0 mg/mL) levels. Furthermore, the beverage underwent simulated digestion following the INFOGEST protocol to assess its oxidative stability. The analysis of the total phenolic content (TPC) using the Folin-Ciocalteu assay revealed that the beverage contained a TPC of 7.58 ± 0.066 mg GAE/mL, while the phenolics identified by HPLC were catechin (2.149 mg/mL), epicatechin (0.024 mg/mL), protocatechuic acid (0.012 mg/mL), luteolin 7-glucoside (0.001 mg/mL), and kaempferol-3-O-β-rutinoside (0.001 mg/mL). The beverage's TPC was strongly correlated with TAC (R² = 896). Moreover, the beverage showcased inhibitory and bacteriostatic effects against Staphylococcus aureus and Pseudomonas aeruginosa. Lastly, the sensory acceptance test demonstrated that the functional sports beverage was well accepted by the assessors.

The effect of caffeine on subsequent sleep: A systematic review and meta-analysis

The consumption of caffeine in response to insufficient sleep may impair the onset and maintenance of subsequent sleep. This systematic review and meta-analysis investigated the effect of caffeine on the characteristics of night-time sleep, with the intent to identify the time after which caffeine should not be consumed prior to bedtime. A systematic search of the literature was undertaken with 24 studies included in the analysis. Caffeine consumption reduced total sleep time by 45 min and sleep efficiency by 7%, with an increase in sleep onset latency of 9 min and wake after sleep onset of 12 min. Duration (+6.1 min) and proportion (+1.7%) of light sleep (N1) increased with caffeine intake and the duration (-11.4 min) and proportion (-1.4%) of deep sleep (N3 and N4) decreased with caffeine intake. To avoid reductions in total sleep time, coffee (107 mg per 250 mL) should be consumed at least 8.8 h prior to bedtime and a standard serve of pre-workout supplement (217.5 mg) should be consumed at least 13.2 h prior to bedtime. The results of the present study provide evidence-based guidance for the appropriate consumption of caffeine to mitigate the deleterious effects on sleep.

Snoring was related to self-reported daytime sleepiness and tiredness in young adults performing compulsory conscript service

STUDY OBJECTIVES

In young adults performing compulsory military service, fatigue and somnolence are common and presumably associated with objective or self-reported sleep deprivation. We aimed to find out whether objective sleep parameters from ambulatory polysomnography could explain their self-reported tiredness and sleepiness and whether habits were associated with sleep parameters or tiredness.

METHODS

Seventy (67 male, age 18-24 years) participants had their sleep assessed with polysomnography. Their self-reported symptoms and demographic data were obtained from online survey including Epworth Sleepiness Scale, Beck's Depression Inventory, items from Basic Nordic Sleep Questionnaire, Internet Addiction Scale, and lifestyle questions.

RESULTS

Snoring (audio recording, percentage of total sleep time) was associated with self-reported sleepiness (P = .010) and tiredness (P = .030) and snoring seemed to, partially, explain sleepiness (P = .029). Twenty-six percent of the conscripts had self-reported sleep deprivation (mismatch between reported need for sleep and reported sleep). Self-reported sleep deprivation was significantly associated with somnolence (P = .016) and fatigue (P = .026). Smartphone usage, both average time (P = .022) and frequency of usage (P = .0093) before bedtime, was associated with shorter total sleep time. On average, objective sleep time was rather short (7 hours, 6 minutes), sleep efficiency high (94.9%), proportion of N3 sleep high (27.7%), and sleep latency brief (9 minutes)-suggesting that many of the conscripts might have chronic partial sleep deprivation.

CONCLUSIONS

Snoring might predispose to tiredness in presumably healthy young adults. Conscripts may have partial sleep deprivation.

CITATION

Orjatsalo M, Toppila J, Heimola M, et al. Snoring was related to self-reported daytime sleepiness and tiredness in young adults performing compulsory conscript service. J Clin Sleep Med. 2023;19(2):243-251.

The role of insufficient sleep and circadian misalignment in obesity

Traditional risk factors for obesity and the metabolic syndrome, such as excess energy intake and lack of physical activity, cannot fully explain the high prevalence of these conditions. Insufficient sleep and circadian misalignment predispose individuals to poor metabolic health and promote weight gain and have received increased research attention in the past 10 years. Insufficient sleep is defined as sleeping less than recommended for health benefits, whereas circadian misalignment is defined as wakefulness and food intake occurring when the internal circadian system is promoting sleep. This Review discusses the impact of insufficient sleep and circadian misalignment in humans on appetite hormones (focusing on ghrelin, leptin and peptide-YY), energy expenditure, food intake and choice, and risk of obesity. Some potential strategies to reduce the adverse effects of sleep disruption on metabolic health are provided and future research priorities are highlighted. Millions of individuals worldwide do not obtain sufficient sleep for healthy metabolic functions. Furthermore, modern working patterns, lifestyles and technologies are often not conducive to adequate sleep at times when the internal physiological clock is promoting it (for example, late-night screen time, shift work and nocturnal social activities). Efforts are needed to highlight the importance of optimal sleep and circadian health in the maintenance of metabolic health and body weight regulation.

Sleep Deprivation, Burnout, and Acute Care Surgery

Purpose of Review

To define what sleep deprivation is, how it relates to the growing problem of burnout within surgeons, and what can be done to mitigate its effects.

Recent Findings

There is a growing awareness that sleep deprivation, in both its acute and chronic manifestations, plays an immense role in burnout. The physical and mental manifestations of sleep deprivation are manifold, effecting nearly every physiologic system. Studies evaluating strategies at mitigating the effects of sleep deprivation are promising, including work done with napping, stimulant use, and service restructuring, but are fundamentally limited by generalizability, scale, and scope.

Summary

The overwhelming majority of data published on sleep deprivation is limited by size, scope, and generalizability. Within acute care surgery, there is a dearth of studies that adequately define and describe sleep deprivation as it pertains to high-performance professions. Given the growing issue of burnout amongst surgeons paired with a growing patient population that is older and more complex, strategies to combat sleep deprivation are paramount for surgeon retention and wellbeing.

Brain activity during a working memory task after daily caffeine intake and caffeine withdrawal: a randomized double-blind placebo-controlled trial

Acute caffeine intake has been found to increase working memory (WM)-related brain activity in healthy adults without improving behavioral performances. The impact of daily caffeine intake-a ritual shared by 80% of the population worldwide-and of its discontinuation on working memory and its neural correlates remained unknown. In this double-blind, randomized, crossover study, we examined working memory functions in 20 young healthy non-smokers (age: 26.4 ± 4.0 years; body mass index: 22.7 ± 1.4 kg/m²; and habitual caffeine intake: 474.1 ± 107.5 mg/day) in a 10-day caffeine (150 mg × 3 times/day), a 10-day placebo (3 times/day), and a withdrawal condition (9-day caffeine followed by 1-day placebo). Throughout the 10th day of each condition, participants performed four times a working memory task (N-Back, comprising 3- and 0-back), and task-related blood-oxygen-level-dependent (BOLD) activity was measured in the last session with functional magnetic resonance imaging. Compared to placebo, participants showed a higher error rate and a longer reaction time in 3- against 0-back trials in the caffeine condition; also, in the withdrawal condition we observed a higher error rate compared to placebo. However, task-related BOLD activity, i.e., an increased attention network and decreased default mode network activity in 3- versus 0-back, did not show significant differences among three conditions. Interestingly, irrespective of 3- or 0-back, BOLD activity was reduced in the right hippocampus in the caffeine condition compared to placebo. Adding to the earlier evidence showing increasing cerebral metabolic demands for WM function after acute caffeine intake, our data suggest that such demands might be impeded over daily intake and therefore result in a worse performance. Finally, the reduced hippocampal activity may reflect caffeine-associated hippocampal grey matter plasticity reported in the previous analysis. The findings of this study reveal an adapted neurocognitive response to daily caffeine exposure and highlight the importance of classifying impacts of caffeine on clinical and healthy populations.

Association of sleep with cognitive function during retirement transition: the Whitehall II study

STUDY OBJECTIVES

Sleep duration and difficulties have been shown to associate with cognitive function. This study examined how changes in sleep and in cognitive function are associated during retirement transition.

METHODS

The study population consisted of 2980 Whitehall II study participants, who retired during the follow-up, whose sleep was queried, and cognitive function measured (inductive reasoning and verbal memory) before and after retirement (follow-up 16 years). Using the last information on sleep before and the first after retirement, participants were categorized into constantly without (59%), increasing (13%), decreasing (11%), and constantly with (18%) sleep difficulties; and constantly short (26%), increasing (19%), decreasing (8.5%), and constantly mid-range (47%) sleep duration. Change in cognitive function during retirement transition was examined by sleep change groups using linear regression analyses with generalized estimating equations.

RESULTS

More pronounced decline in inductive reasoning during retirement transition was observed among participants with increasing sleep difficulties (-1.96, 95% CI -2.52 to -1.41) compared to those constantly without sleep difficulties (-1.25, 95% CI -1.52 to -0.98) and constantly with sleep difficulties (-1.26, 95% CI -1.75 to -0.92). Decreasing sleep difficulties (-0.64, 95% CI -0.86 to -0.43) were associated with a more pronounced decline in verbal memory when compared to constantly without sleep difficulties (-0.42, 95% CI -0.52 to -0.32) in post-retirement period. No statistically significant differences across sleep duration groups in cognitive function were observed.

CONCLUSIONS

Increasing and decreasing sleep difficulties may be associated with accelerated decline in cognitive function during retirement transition and post-retirement.

Relationship between genetic polymorphisms of cytokines and self-reported sleep complaints and habitual caffeine consumption

Pro-inflammatory cytokines are involved in sleep-wake regulation and are associated with caffeine consumption. This is a cross-sectional study in 1023 active French workers investigating associations between self-reported sleep complaints (>3months) and total sleep time (TST) with nine single-nucleotide-polymorphisms (SNPs) including pro-inflammatory cytokines, according to caffeine consumption. Participants were characterized as low, moderate and high (0-50, 51-300, and >300 mg/day) caffeine consumers. After adjusting the odd ratios (OR) for age, gender, and smoking, the risk of sleep complaints was higher in subjects with genetic mutations in tumor necrosis factor alpha (TNF-α, rs 1800629) (ORa [95%CI] = 1.43 [1.07-1.92] for both G/A and A/A aggregate genotypes) or interleukin-1 beta (IL-1β, rs1143627) (ORa = 1.61 [1.08-2.44] for homozygous A/A genotype), and the risk was higher when subjects carry the mutations in TNF-α plus IL-1β regardless of caffeine consumption. When stratified with caffeine consumption, the risk of sleep complaints was higher in TNF-α A allele carriers in high caffeine consumers, and in homozygous A/A genotype of IL-1β in moderate and high consumers. None of the nine SNPs influence TST, with the exception of the mutation on CYP1A2 and only when stratified with caffeine consumption. Our results also indicated more caffeine side-effects when carrying mutation on IL1β. This study showed that polymorphisms in TNF-α and/or IL-1β influenced sleep complaints but did not influence total sleep time. This suggests that management of sleep complaints, which can be addressed by clinical interventions, should consider the influence of the genetic profile of pro-inflammatory cytokines.

Caffeine consumption as a risk factor for childhood and adolescence migraine

BACKGROUND

Caffeine consumption is a risk factor for chronic daily headache but few studies have addressed relationships between pediatric patient caffeine levels and headache severity. We examined associations between serum and urine caffeine levels and headache severity in childhood and adolescent migraine cases.

METHODS

Levels of caffeine and caffeine metabolites in serum and urine samples were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The Wilcoxon rank-sum test was used for comparisons of age, sleep time, headache severity, caffeine consumption, and caffeine detection. Spearman's rank correlation coefficient (ρ) was calculated for associations. Correlations where ρ ≥ 0.3 and differences where p < 0.05 were considered statistically significant.

RESULTS

Of the 40 patients studied, 34 declared caffeine consumption and six declared no caffeine consumption. These two groups did not differ significantly in any of the above clinical parameters. Liquid chromatography-tandem mass spectrometry analysis of both serum and urine samples revealed nine caffeine-negative (level <0.0625 μM) and 31 caffeine-positive cases. The Headache Impact Test-6 (HIT-6) score was higher (p = 0.033) for the caffeine-positive group versus the caffeine-negative group. Caffeine was detected by LC-MS/MS in the serum and/or urine of three of the six patients who declared no caffeine consumption. No significant correlations were observed among age, sleep times, headache severity score, or levels of caffeine and caffeine metabolites.

CONCLUSION

Thirty one of 40 (77.5%) cases of childhood/ adolescence migraine showed serum and urine caffeine positivity based on LC-MS/MS. The HIT-6 score, a measure of headache severity, was significantly higher for caffeine-positive versus caffeine-negative cases. Symptoms of childhood/adolescence migraine were exacerbated by caffeine consumption.

The Effects of Frequent Coffee Drinking on Female-Dominated Healthcare Workers Experiencing Musculoskeletal Pain and a Lack of Sleep

Previous research has demonstrated that chronic diseases can occur due to musculoskeletal (MS) pain and poor sleep. It is also worth noting that the caffeine in coffee can reduce overall sleep duration, efficiency, and quality. Thus, the present study examines the effects of frequent coffee drinking (two cups per day) on individuals experiencing MS pain and a lack of sleep during the COVID-19 period. This observational and cross-sectional study recruited 1615 individuals who completed the self-reported (Nordic musculoskeletal) questionnaire. Long-term, frequent coffee drinking and a sleep duration of less than 6 h per day were significantly associated with neck and shoulder pain among healthy individuals. The mediation model demonstrated that the shorter sleep duration and drinking multiple cups of coffee per day had a two-way relationship that worsened such pain over the long term. Specifically, individuals who experienced such pain frequently drank multiple cups of coffee per day, which, in turn, shortened their sleep durations. In summary, long-term coffee drinking creates a vicious cycle between MS pain and sleep duration. Therefore, the amount of coffee should be fewer than two cups per day for individuals who sleep less than 6 h per day or suffer from MS pain, especially neck and shoulder pain.

Combined Exposure to Chronic Sleep Deprivation and Caffeine Potentiates Behavioural Deficits by Altering Neurochemical Profile and Synaptophysin Expression in Long-Evans Rats

Using the Unpredictable Chronic Sleep Deprivation (UCSD) paradigm we developed, the combined effects of chronic sleep deprivation and high caffeine intake on prefrontal cortical synaptophysin expression, neurochemical profiles, and behavioural outcomes in Long-Evans rats were evaluated. The combination of chronic sleep deprivation and high-dose caffeine treatment produced varying degrees of behavioural impairments, depletion of antioxidants, serotonin, and an upregulation of acetylcholinesterase (AChE) activity in the prefrontal cortex. An immunohistochemical assessment revealed a reduction in synaptophysin protein expression in the prefrontal cortex following exposure to high-dose caffeine and chronic sleep deprivation. Overall, our findings support the advocacy for adequate sleep for optimal mental performance as a high intake of caffeine to attenuate the effects of sleep deprivation that may alter the neurochemical profile and synaptic plasticity in the prefrontal cortex, significantly increasing the risk of neuropsychiatric/degenerative disorders.

Precision caffeine therapy for apnea of prematurity and circadian rhythms: New possibilities open up

Caffeine is the globally consumed psychoactive substance and the drug of choice for the treatment of apnea of prematurity (AOP), but its therapeutic effects are highly variable among preterm infants. Many of the molecular underpinnings of the marked individual response have remained elusive yet. Interestingly, the significant association between Clock gene polymorphisms and the response to caffeine therapy offers an opportunity to advance our understanding of potential mechanistic pathways. In this review, we delineate the functions and mechanisms of human circadian rhythms. An up-to-date advance of the formation and ontogeny of human circadian rhythms during the perinatal period are concisely discussed. Specially, we summarize and discuss the characteristics of circadian rhythms in preterm infants. Second, we discuss the role of caffeine consumption on the circadian rhythms in animal models and human, especially in neonates and preterm infants. Finally, we postulate how circadian-based therapeutic initiatives could open new possibilities to promote precision caffeine therapy for the AOP management in preterm infants.

Caffeine-Induced Sleep Restriction Alters the Gut Microbiome and Fecal Metabolic Profiles in Mice

Insufficient sleep is becoming increasingly common and contributes to many health issues. To combat sleepiness, caffeine is consumed daily worldwide. Thus, caffeine consumption and sleep restriction often occur in succession. The gut microbiome can be rapidly affected by either one's sleep status or caffeine intake, whereas the synergistic effects of a persistent caffeine-induced sleep restriction remain unclear. In this study, we investigated the impact of a chronic caffeine-induced sleep restriction on the gut microbiome and its metabolic profiles in mice. Our results revealed that the proportion of Firmicutes and Bacteroidetes was not altered, while the abundance of Proteobacteria and Actinobacteria was significantly decreased. In addition, the content of the lipids was abundant and significantly increased. A pathway analysis of the differential metabolites suggested that numerous metabolic pathways were affected, and the glycerophospholipid metabolism was most significantly altered. Combined analysis revealed that the metabolism was significantly affected by variations in the abundance and function of the intestinal microorganisms and was closely relevant to Proteobacteria and Actinobacteria. In conclusion, a long-term caffeine-induced sleep restriction affected the diversity and composition of the intestinal microbiota in mice, and substantially altered the metabolic profiles of the gut microbiome. This may represent a novel mechanism by which an unhealthy lifestyle such as mistimed coffee breaks lead to or exacerbates disease.

Determinants of natural adult sleep: An umbrella review

BACKGROUND

Sleep has a major impact on health, which makes it a relevant topic for research and health practitioners. Research on sleep determinants, i.e. factors that positively or negatively influence sleep, is fragmented.

OBJECTIVE

The purpose of this umbrella review is to provide an overview of the current evidence on determinants of natural adult sleep.

METHODS

A comprehensive literature search was performed on determinants of sleep. Reviews and meta-analyses on natural adult sleep were included. Six electronic databases (PubMed, WoS, Embase, CINAHL, PsycInfo and Cochrane) were used for the search, last accessed September 2021. The quality of the selected articles was assessed using the AMSTAR2 tool. Results were categorized in four main categories: biological, behavioral, environmental and personal/socio-economical determinants.

RESULTS

In total 93 reviews and meta-analyses resulted in a total of 30 identified determinants. The impact of each determinant differs per individual and per situation. Each determinant was found to affect different sleep parameters and the relationship with sleep is influenced by both generic and specific moderators.

DISCUSSION

A comprehensive overview on relevant sleep determinants provides a practical and scientifically based starting point to identify relevant intervention approaches to secure or improve individual sleep quality. The difference in aggregation level of the determinants and in measurement methods are the major limitations of this umbrella review. Extending existing generic sleep hygiene rules with an overview of all types of potential determinants will enhance the awareness of the complexity and can be used to improve the effect of sleep interventions in health promotion.

TRIAL REGISTRATION

The umbrella review was registered with PROSPERO (registration ID CRD42020149648) https://www.google.com/search?client=firefox-b-d&q=CRD42020149648.

The association of 1-year weight loss from bariatric surgery and self-reported sleep: a prospective cohort

OBJECTIVE

This study examined the association of weight loss following bariatric surgery with self-reported sleep quality after accounting for other sleep-related factors.

METHODS

Participants were from the Bariatric Experience Long Term (BELONG) study. Participants completed a survey up to 6 months before surgery and approximately 1 year after surgery. The Pittsburgh Sleep Quality Index (PSQI) was used to measure sleep quality. One-year percentage total weight loss (%TWL) was determined from electronic medical records. Covariates included demographics, Charlson Comorbidity Index, geocoded variables to assess neighborhood quality, and physical activity. The authors assessed the association between %TWL at 1 year and PSQI component scores with separate cumulative logit models.

RESULTS

There were 997 participants in the analytic cohort. Participants were 86.2% women, 37.0% Hispanic, and 13.7% Black adults. Mean one-year %TWL was 26.3 (SD 8.7). Each 1% increase in %TWL was associated with a 3% better daytime dysfunction score (odds ratio = 1.03; 95% CI: 1.02-1.05) and a 2% better sleep quality score (odds ratio = 1.02; 95% CI: 1.00-1.03). No significant differences were found for the other PSQI components.

CONCLUSIONS

Weight loss from bariatric surgery was associated with better self-reported sleep at 1 year. For people undergoing bariatric surgery, there may be an added benefit of better sleep.

A study on the changes in life habits, mental health, and sleep quality of college students due to COVID-19

BACKGROUND: In early 2020, the coronavirus 2019 (COVID-19) pandemic necessitated changes in social behavior to prevent its spread, including holding online classes, implementing social distancing, and allowing employees to telecommute. However, these changes have had a negative impact on people’s sleep patterns and mental health, particularly for college students. OBJECTIVE: This study investigated the relationship between mental health and sleep quality according to the changes in lifestyle of college students in the periods before and after COVID-19. METHODS: The study subjects were 164 college students from Korea who had both face-to-face and non-face-to-face college experiences before and after COVID-19. The experiment was conducted using a Google survey, and the participants were recruited from the college community. The general features and lifestyle habits for the individuals were assessed using the AUDIT-K, Delphi method, KGHQ (General Mental Health Scale), and PSQI-K (Pittsburg Sleep Quality Index). RESULTS: The KGHQ and PSQI scores increased with the spread of COVID-19, which means that the mental health and sleep quality of college students deteriorated. 11 categories of variables were further investigated to evaluate changes in lifestyle, and the results indicate significant changes in the number of private meetings per week, monthly drinking, outdoor activity time, electronic device usage time, weekly food delivery, weekly late-night snacks, daily snacks, and daily coffee intake and no significant changes in exercise, smoking, and fast food intake. CONCLUSION: COVID-19 caused many changes in the lifestyle of college students, which adversely affected mental health and sleep.

The Impact of Dietary Factors on the Sleep of Athletically Trained Populations: A Systematic Review

Many athletic populations report poor sleep, especially during intensive training and competition periods. Recently, diet has been shown to significantly affect sleep in general populations; however, little is known about the effect diet has on the sleep of athletically trained populations. With sleep critical for optimal recovery and sports performance, this systematic review aimed to evaluate the evidence demonstrating that dietary factors influence the sleep of athletically trained populations. Four electronic databases were searched from inception to May 2022, with primary research articles included if they contained a dietary factor(s), an outcome measure of sleep or sleepiness, and participants could be identified as ‘athletically trained’. Thirty-five studies were included, with 21 studies assessed as positive quality, 13 as neutral, and one as negative. Sleep or sleepiness was measured objectively in 46% of studies (n = 16). The review showed that evening (≥5 p.m.) caffeine intakes >2 mg·kg−1 body mass decreased sleep duration and sleep efficiency, and increased sleep latency and wake after sleep onset. Evening consumption of high glycaemic index carbohydrates and protein high in tryptophan may reduce sleep latency. Although promising, more research is required before the impact of probiotics, cherry juice, and beetroot juice on the sleep of athletes can be resolved. Athletic populations experiencing sleep difficulties should be screened for caffeine use and trial dietary strategies (e.g., evening consumption of high GI carbohydrates) to improve sleep.

The magical smell and taste: Can coffee be good to patients with cardiometabolic disease?

Coffee is a beverage consumed globally. Although few studies have indicated adverse effects, it is typically a beneficial health-promoting agent in a range of diseases, including depression, diabetes, cardiovascular disease, and obesity. Coffee is rich in caffeine, antioxidants, and phenolic compounds, which can modulate the composition of the gut microbiota and mitigate both inflammation and oxidative stress, common features of the burden of lifestyle diseases. This review will discuss the possible benefits of coffee on complications present in patients with diabetes, cardiovascular disease and chronic kidney disease, outwith the social and emotional benefits attributed to caffeine consumption.

Coffee and tea consumption, patient-reported, and clinical outcomes in a longitudinal study of patients with breast cancer

Background

Higher consumption of coffee and tea has been associated with improved health outcomes in the general population and improved breast cancer (BC) prognosis. This study investigated patterns of coffee and tea consumption and association with patient‐reported outcomes (PROs) and clinical outcomes among survivors of BC.

Methods

The authors included survivors of stage I–III BC enrolled in the CANTO cohort (NCT01993498) that provided post‐treatment assessment of coffee and tea consumption from years 1 to 4 after diagnosis. Group‐based trajectory modeling clustered patients according to daily consumption of coffee and tea. Multivariable mixed models and Cox models examined associations between consumption, PROs and clinical outcomes.

Results

Among 3788 patients, the authors identified four stable patterns of consumption: “Low” (25.8%), “Moderate” (37.6%), “High” (25.3%), and “Very high” (11.3%), corresponding to <1, 2, 3, and ≥ 4 cups of coffee and/or tea per day. Patients in the “Very high” group (vs. “Low”), were more likely to be younger, smokers, with higher monthly income and education. PROs and survival outcomes were similar across the four groups.

Conclusions

Over one in three survivors of BC reported high or very high consumption of coffee and/or tea. The authors found no association between higher consumption of coffee and/or tea, worse PROs and clinical outcomes.

More than 30% of survivors of breast cancer report high post‐diagnostic consumption of coffee and tea. In this study, the authors did not find any detrimental association between higher consumption of coffee and tea and patient‐reported or clinical outcomes.

Association between coffee consumption and periodontal diseases: a systematic review and meta-analysis

BACKGROUND

Several studies have demonstrated association between coffee consumption and periodontal diseases. However, no systematic review and meta-analysis was performed. Therefore, we performed a systematic review and meta-analysis to evaluate the association between coffee intake and periodontitis.

METHODS

We defined PICO statement as "Do coffee drinkers have a higher association of periodontitis or tooth loss than non-coffee drinkers?". We searched for articles using the Embase and Medline databases. The odds ratio was used as an effect measure to evaluate the association between coffee and periodontitis We divided coffee intake doses into three groups: no intake (≤ 0.03 cups/day), low intake (0.03 < x < 1 cups/day), and high intake (≥ 1 cup/day). Cohort and cross-sectional studies were eligible for inclusion in this study. The Newcastle-Ottawa scale was used to qualitatively assess the risk of bias. The degree of heterogeneity between studies was quantified using I² statistics.

RESULTS

Six articles were analysed, including two cohort studies and four cross-sectional studies. The pooled unadjusted odds ratios of periodontitis were 1.14 (0.93-1.39), 1.05 (0.73-1.52), 1.03 (0.91-1.16) and 1.10 (0.84-1.45) in the 4 meta-analyses (coffee drinker vs. non-coffee drinker, high intake vs. low intake, low intake vs. no intake, high intake vs. no intake), respectively.

CONCLUSION

This is the first meta-analysis to investigate the relationship between coffee consumption and periodontitis. There was no relationship between coffee consumption and periodontitis. Further studies are required to assess whether a relationship between coffee consumption and periodontitis exists or not. PROSPERO registration number: CRD42022301341.

Sleep and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery, and Mental Health: An Update

Sleep health is an important consideration for athletic performance. Athletes are at high risk of insufficient sleep duration, poor sleep quality, daytime sleepiness and fatigue, suboptimal sleep schedules, irregular sleep schedules, and sleep and circadian disorders. These issues likely have an impact on athletic performance via several domains. Sleep loss and/or poor sleep quality can impair muscular strength, speed, and other aspects of physical performance. Sleep issues can also increase risk of concussions and other injuries and impair recovery after injury. Cognitive performance is also impacted in several domains, including vigilance, learning and memory, decision making, and creativity.

Acute Sleep Deprivation Impairs Motor Inhibition in Table Tennis Athletes: An ERP Study

Excellent response inhibition is the basis for outstanding competitive athletic performance, and sleep may be an important factor affecting athletes’ response inhibition. This study investigates the effect of sleep deprivation on athletes’ response inhibition, and its differentiating effect on non-athlete controls’ performance, with the aim of helping athletes effectively improve their response inhibition ability through sleep pattern manipulation. Behavioral and event-related potential (ERP) data were collected from 36 participants (16 table tennis athletes and 20 general college students) after 36 h of sleep deprivation using ERP techniques and a stop-signal task. Sleep deprivation’s different effects on response inhibition in the two groups were explored through repeated-measures ANOVA. Behavioral data showed that in a baseline state, stop-signal response time was significantly faster in table tennis athletes than in non-athlete controls, and appeared significantly longer after sleep deprivation in both groups. ERP results showed that at baseline state, N2, ERN, and P3 amplitudes were lower in table tennis athletes than in non-athlete controls, and corresponding significant decreases were observed in non-athlete controls after 36 h of sleep deprivation. Table tennis athletes showed a decrease in P3 amplitude and no significant difference in N2 and ERN amplitudes, after 36 h of sleep deprivation compared to the baseline state. Compared to non-athlete controls, table tennis athletes had better response inhibition, and the adverse effects of sleep deprivation on response inhibition occurred mainly in the later top-down motor inhibition process rather than in earlier automated conflict detection and monitoring.

The moderating role of gender in the association between quality of social relationships and sleep

To determine whether the association between perceived social support or strain in close relationships and sleep outcomes varies by gender. Participants were selected from the Biomarker projects of either the MIDUS II or MIDUS Refresher study if they were in a married-or married-like relationship and shared a bed with their partner (N = 989). A subsample also participated in a seven-day sleep study (n = 282). Perceived social support and strain from partner, family, and friends were examined by self-report questionnaires. We used the Pittsburgh Sleep Quality Index, sleep daily diary, and actigraphy to measure both subjective and objective sleep. Social support and strain were both associated with sleep outcomes. Specifically, higher social support was associated with fewer daily reports of light sleep and feeling more rested in the morning, while higher social strain was associated with higher clinical sleep disturbance. For women, but not men, social support was significantly associated with lower daily sleep disturbance while perceived social strain was significantly associated with higher daily sleep disturbance, lighter sleep, feeling less rested in the morning, lower sleep efficiency, and longer sleep onset latency. Mainly among women, social support and strain are associated with an important transdiagnostic health outcome-sleep-which may have implications for a wide range of health disparities. Interpersonal stressors may increase health risks differently for women compared to men and one mechanism that may link social relationships to long-term health outcomes is sleep.

The gut microbiota-bile acid axis links the positive association between chronic insomnia and cardiometabolic diseases

Evidence from human cohorts indicates that chronic insomnia is associated with higher risk of cardiometabolic diseases (CMD), yet whether gut microbiota plays a role is unclear. Here, in a longitudinal cohort (n = 1809), we find that the gut microbiota-bile acid axis may link the positive association between chronic insomnia and CMD. Ruminococcaceae UCG-002 and Ruminococcaceae UCG-003 are the main genera mediating the positive association between chronic insomnia and CMD. These results are also observed in an independent cross-sectional cohort (n = 6122). The inverse associations between those gut microbial biomarkers and CMD are mediated by certain bile acids (isolithocholic acid, muro cholic acid and nor cholic acid). Habitual tea consumption is prospectively associated with the identified gut microbiota and bile acids in an opposite direction compared with chronic insomnia. Our work suggests that microbiota-bile acid axis may be a potential intervention target for reducing the impact of chronic insomnia on cardiometabolic health.

Chronic insomnia is associated with cardiometabolic diseases. Here, in two clinical cohorts (n = 7,931), authors show that gut microbiota-bile acid axis may be an intervention target to attenuate the impact of chronic insomnia on cardiometabolic health.

Long-Term Effect of a Single Dose of Caffeine on Sleep, the Sleep EEG and Neuronal Activity in the Peduncular Part of the Lateral Hypothalamus under Constant Dark Conditions

Background: Caffeine is a central nervous system stimulant that influences both the sleep–wake cycle and the circadian clock and is known to influence neuronal activity in the lateral hypothalamus, an important area involved in sleep–wake regulation. Light is a strong zeitgeber and it is known to interact with the effect of caffeine on the sleep–wake cycle. We therefore wanted to investigate the long-term effects of a single dose of caffeine under constant dark conditions. Methods: We performed long-term (2 days) electroencephalogram (EEG)/electromyogram recordings combined with multi-unit neuronal activity recordings in the peduncular part of the lateral hypothalamus (PLH) under constant darkness in Brown Norway rats, and investigated the effect of a single caffeine treatment (15 mg/kg) or saline control given 1 h after the onset of the endogenous rest phase. Results: After a reduction in sleep and an increase in waking and activity in the first hours after administration, also on the second recording day after caffeine administration, rapid eye movement (REM) sleep was still reduced. Analysis of the EEG showed that power density in the theta range during waking and REM sleep was increased for at least two days. Neuronal activity in PLH was also increased for two days after the treatment, particularly during non-rapid eye movement sleep. Conclusion: Surprisingly, the data reveal long-term effects of a single dose of caffeine on vigilance states, EEG, and neuronal activity in the PLH. The absence of a light–dark cycle may have enabled the expression of these long-term changes. It therefore may be that caffeine, or its metabolites, have a stronger and longer lasting influence, particularly on the expression of REM sleep, than acknowledged until now.

Adenosine, caffeine, and sleep-wake regulation: state of the science and perspectives

For hundreds of years, mankind has been influencing its sleep and waking state through the adenosinergic system. For ~100 years now, systematic research has been performed, first started by testing the effects of different dosages of caffeine on sleep and waking behaviour. About 70 years ago, adenosine itself entered the picture as a possible ligand of the receptors where caffeine hooks on as an antagonist to reduce sleepiness. Since the scientific demonstration that this is indeed the case, progress has been fast. Today, adenosine is widely accepted as an endogenous sleep‐regulatory substance. In this review, we discuss the current state of the science in model organisms and humans on the working mechanisms of adenosine and caffeine on sleep. We critically investigate the evidence for a direct involvement in sleep homeostatic mechanisms and whether the effects of caffeine on sleep differ between acute intake and chronic consumption. In addition, we review the more recent evidence that adenosine levels may also influence the functioning of the circadian clock and address the question of whether sleep homeostasis and the circadian clock may interact through adenosinergic signalling. In the final section, we discuss the perspectives of possible clinical applications of the accumulated knowledge over the last century that may improve sleep‐related disorders. We conclude our review by highlighting some open questions that need to be answered, to better understand how adenosine and caffeine exactly regulate and influence sleep.

Self-reported sleep and circadian characteristics predict alcohol and cannabis use: A longitudinal analysis of the National Consortium on Alcohol and Neurodevelopment in Adolescence Study

BACKGROUND

Growing evidence indicates that sleep characteristics predict future substance use and related problems. However, most prior studies assessed a limited range of sleep characteristics, studied a narrow age span, and included few follow-up assessments. Here, we used six annual assessments from the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) study, which spans adolescence and young adulthood with an accelerated longitudinal design, to examine whether multiple sleep characteristics in any year predict alcohol and cannabis use the following year.

METHODS

The sample included 831 NCANDA participants (423 females; baseline age 12-21 years). Sleep variables included circadian preference, sleep quality, daytime sleepiness, the timing of midsleep (weekday/weekend), and sleep duration (weekday/weekend). Using generalized linear mixed models (logistic for cannabis; ordinal for binge severity), we tested whether each repeatedly measured sleep characteristic (years 0-4) predicted substance use (alcohol binge severity or cannabis use) the following year (years 1-5), covarying for age, sex, race, visit, parental education, and previous year's substance use.

RESULTS

Greater eveningness, more daytime sleepiness, later weekend sleep timing, and shorter sleep duration (weekday/weekend) all predicted more severe alcohol binge drinking the following year. Only greater eveningness predicted a greater likelihood of any cannabis use the following year. Post-hoc stratified exploratory analyses indicated that some associations (e.g., greater eveningness and shorter weekend sleep duration) predicted binge severity only in female participants, and that middle/high school versus post-high school adolescents were more vulnerable to sleep-related risk for cannabis use.

CONCLUSIONS

Our findings support the relevance of multiple sleep/circadian characteristics in the risk for future alcohol binge severity and cannabis use. Preliminary findings suggest that these risk factors vary based on developmental stage and sex. Results underscore a need for greater attention to sleep/circadian characteristics as potential risk factors for substance use in youth and may inform new avenues to prevention and intervention.

The Impact of Lockdowns on Caffeine Consumption: A Systematic Review of the Evidence

The Coronavirus disease 2019 (COVID-19) has been characterized by the World Health Organization as a pandemic in March 2020 and the lockdown measures that were implemented in an effort to limit the transmission of the virus affected the daily life of many people in all over the world. The aim of this systematic review was to investigate the changes during/after the lockdowns in caffeine consumption by coffee and energy drinks. A systematic literature search was conducted in three databases (PubMed, Embase, Web of Science) up to 31 December 2021 and out of 19,511 studies found and 12,885 screened, 16 studies were included according to eligibility criteria. Results regarding coffee consumption showed that a significant part of individuals decreased their consumption and in five studies an increase was reported, including women and seniors >60 years old. Energy drinks were also consumed less during the lockdown compared to the pre-lockdown time. Attention should be given for menopausal women where an increase in coffee consumption was found which could impair bone density, but further research is needed in order to make safe conclusions.

Caffeine Intake among Undergraduate Students: Sex Differences, Sources, Motivations, and Associations with Smoking Status and Self-Reported Sleep Quality

Due to its stimulatory effects, caffeine is one of the most frequently consumed mood and behavior altering drugs. University students report using caffeine-containing products to enhance mood and performance or for a desire of alertness. The current study investigated caffeine consumption in university undergraduate students, and associations with smoking status, alcohol and cannabis consumption, fruit and vegetable consumption, and sleep quality. Motivations for caffeine intake were also ascertained. A total of 886 undergraduates aged 18−25 years from the University of the Balearic Islands participated in a cross-sectional survey. Caffeine was consumed by 91.1% of participants. Caffeine consumers were more likely to be female, smokers, and alcohol and cannabis consumers. Coffee was found to be the main source of caffeine intake in both men and women (48.9% of total caffeine intake). Higher percentages of women consumed coffee (56.4 vs. 42.1%, p = 0.01) and tea (40.3 vs. 19.8%, p < 0.001), whereas a higher percentage of men consumed energy drinks (18.0 vs. 7.4%, p < 0.001). Main motivations for caffeine intake were those related to cognitive enhancement. Caffeine intake was associated with poorer subjective sleep quality (p < 0.001). In conclusion, undergraduate students that were female and smokers reported higher caffeine intakes. Coffee was found as the main caffeine contributor, with higher contributions of tea in women and energy drinks in men. Universities should consider the implementation of health campaigns and educational programs to educate students of the risks of high caffeine consumption together with associated behaviors such as smoking, alcohol consumption and poor sleep quality to physical health and academic performance.

Prevalence of caffeine consumers, daily caffeine consumption, and factors associated with caffeine use among active duty United States military personnel

Background

Although representative data on caffeine intake in Americans are available, these data do not include US service members (SMs). The few previous investigations in military personnel largely involve convenience samples. This cross-sectional study examined prevalence of caffeine consumers, daily caffeine consumption, and factors associated with caffeine use among United States active duty military service members (SMs).

Methods

A stratified random sample of SMs were asked to complete an on-line questionnaire on their personal characteristics and consumption of caffeinated products (exclusive of dietary supplements). Eighteen percent (n = 26,680) of successfully contacted SMs (n = 146,365) completed the questionnaire.

Results

Overall, 87% reported consuming caffeinated products ≥1 time/week. Mean ± standard error per-capita consumption (all participants) was 218 ± 2 and 167 ± 3 mg/day for men and women, respectively. Caffeine consumers ingested 243 ± 2 mg/day (251 ± 2 mg/day men, 195 ± 3 mg/day women). On a body-weight basis, men and women consumed respectively similar caffeine amounts (2.93 vs 2.85 mg/day/kg; p = 0.12). Among individual caffeinated products, coffee had the highest use (68%), followed by sodas (42%), teas (29%), energy drinks (29%) and gums/candy/medications (4%). In multivariable logistic regression, characteristics independently associated with caffeine use (≥1 time/week) included female gender, older age, white race/ethnicity, higher body mass index, tobacco use or former use, greater alcohol intake, and higher enlisted or officer rank.

Conclusion

Compared to National Health and Nutrition Examination Survey data, daily caffeine consumption (mg/day) by SMs was higher, perhaps reflecting higher mental and physical occupational demands on SMs.

The neurophysiologic basis of the human sleep–wake cycle and the physiopathology of the circadian clock: a narrative review

The objectives of this review were to explain the neurologic processes that control the human sleep–wake cycle as well as the pathophysiology of the human circadian clock. Non-rapid eye movement and rapid eye movement sleep are the two main phases of sleep. When triggered by circadian input from the anterior hypothalamus and sleep–wake homeostatic information from endogenous chemical signals (example, adenosine), the ventrolateral preoptic nucleus initiates the onset of sleep. Arousal in which there is a conscious monitoring of the surroundings and the ability to respond to external stimuli is known as wakefulness. It contrasts the state of sleep, in which receptivity to external stimuli is reduced. The higher the synchronous firing rates of cerebral cortex neurons, the longer the brain has been awake. Sleep–wake disturbances induced by endogenous circadian system disruptions or desynchronization between internal and external sleep–wake cycles are known as circadian rhythm sleep–wake disorder (CRSWD). Patients with CRSWD usually report chronic daytime drowsiness and/or insomnia, which interferes with their activities. CRSWD is diagnosed based on the results of some functional evaluations, which include measuring the circadian phase using core body temperature, melatonin secretion timing, sleep diaries, actigraphy, and subjective experiences (example, using the Morningness–Eveningness Questionnaire). CRSWD is classified as a dyssomnia in the second edition of the International Classification of Sleep Disorders, with six subtypes: advanced sleep phase, delayed sleep phase, irregular sleep–wake, free running, jet lag, and shift work types. CRSWD can be temporary (due to jet lag, shift work, or illness) or chronic (due to delayed sleep–wake phase disorder, advanced sleep–wake phase disorder, non-24-h sleep–wake disorder, or irregular sleep–wake rhythm disorder). The inability to fall asleep and wake up at the desired time is a common symptom of all CRSWDs.

Recent advances in the utilization of tea active ingredients to regulate sleep through neuroendocrine pathway, immune system and intestinal microbiota

Sleep disorders have received widespread attention nowadays, which have been promoted by the accelerated pace of life, unhealthy diets and lack of exercise in modern society. The chemical medications to improve sleep has shown serious side effects and risks with high costs. Therefore, it is urgent to develop efficient nutraceuticals from natural sources to ensure sleep quality as a sustainable strategy. As the second most consumed beverage worldwide, the health-promoting effects of tea have long been widely recognized. However, the modulatory effect of teas on sleep disorders has received much less attention. Tea contains various natural sleep-modulating active ingredients such as L-theanine (LTA), caffeine, tea polyphenols (TPP), tea pigments, tea polysaccharides (TPS) and γ-aminobutyric acid (GABA). This review focuses on the potential influence and main regulating mechanisms of different tea active ingredients on sleep, including being absorbed by the small intestine and then cross the blood-brain barrier to act on neurons in the brain as neurotransmitters, manipulating the immune system and further affect sleep-wake cycle by regulating the levels of cytokines, and controlling the gut microbes to maintain the homeostasis of circadian rhythm. Current research progress and limitations are summarized and several future development directions are also proposed. This review hopes to provide new insights into the future elucidation of the sleep-regulating mechanisms of different teas and their natural active ingredients and the development of tea-based functional foods for alleviating sleep disorders. HighlightsNatural sleep-modulating active ingredients in tea have been summarized.Influences of drinking tea or tea active ingredients on sleep are reviewed.Three main regulating mechanisms of tea active ingredients on sleep are explained.The associations among nervous system, immune system and intestinal microbiota are investigated.The potential of developing delivery carriers for tea active ingredients is proposed.

Maladaptive coping mechanisms of sleep

ABSTRACT

Patients with insomnia have been shown to use many maladaptive coping mechanisms. This article examines the effect of such coping mechanisms on sleep quality by reviewing results of polysomnography and the Epworth Sleepiness Scale among 137 patients. The study showed that sleep quality was affected by these mechanisms.

Assessment of sick building syndrome using visual analog scales

BACKGROUND

Despite there is no recommendations for assessing symptoms of sick building syndrome, the use of visual analog scales (VAS) seems attractive and appropriate. We aimed to demonstrate the benefits of using VAS for evaluating subjective symptoms of sick building syndrome.

METHOD

We compared an exposed group to a control group with a one-year follow-up. To assess chronology of symptoms, employees were asked to complete four VAS at different times: after vacations (time 1), beginning of the week-beginning of the day (time 2), beginning of the week-end of the day (time 3), and end of the week-end of the day (time 4). Measurements were repeated before and after ventilation work for the exposed group and at the same time in the control group without intervention. Confounding factors were assessed.

RESULTS

We included 36 employees (21 in the exposed group and 15 in the control group). Both groups were comparable. Prior to ventilation work, the exposed group had more subjective symptoms than the control group with a chronology of symptoms. After ventilation work, symptoms did not differ between groups, and most symptoms decreased within the exposed group.

PRACTICAL IMPLICATION

The use of VAS provided reliable data for assessing sick building syndrome and showed a dose-response relationship between occupational exposure and symptoms.