Habitual Caffeine Consumption Research Articles

Caffeine Intake Alters Recovery Sleep after Sleep Deprivation.

Caffeine is a well-known psychostimulant reputed to alleviate the deleterious effects of sleep deprivation. Nevertheless, caffeine can alter sleep duration and quality, particularly during recovery sleep. We evaluated the effects of acute caffeine intake on the duration and quality of recovery sleep following total sleep deprivation (TSD), taking into account daily caffeine consumption. Forty-one participants performed a double-blind, crossover TSD protocol (38 h of continuous wakefulness) with acute caffeine or placebo. Caffeine (2.5 mg/kg) or placebo was administered twice during continuous wakefulness (last treatment 6.5 h before bedtime for the recovery night). Polysomnographic measurements were recorded using a connected headband. TSD was associated with a rebound in total sleep time (TST) on the recovery night (+110.2 ± 23.2 min, p < 0.001). Caffeine intake decreased this recovery TST (-30.2 ± 8.2 min p = 0.02) and the N3 sleep stage duration (-35.6 ± 23.2 min, p < 0.01). Caffeine intake altered recovery sleep continuity (increased number of long awakenings), stability (higher stage transition frequency), and organization (less time spent in complete sleep cycle) and decreased the delta power spectral density during NREM sleep. On the recovery night, habitual daily caffeine consumption was negatively correlated with TST in caffeine and placebo conditions and positively correlated with wake after sleep onset (WASO) duration and with the frequency of long (>2 min) awakenings in the caffeine condition only. Acute caffeine intake during TSD affects nighttime recovery sleep, with an interaction with daily consumption. These results may influence advice on caffeine intake for night-shift workers. (NCT03859882).

Habitual Coffee, Tea, and Caffeine Consumption, Circulating Metabolites, and the Risk of Cardiometabolic Multimorbidity.

Cardiometabolic multimorbidity (CM) is an increasing public health concern. Previous observational studies have suggested inverse associations between coffee, tea, and caffeine intake and risks of individual cardiometabolic diseases; however, their associations with CM and related biological markers are unknown. This prospective study involved 172 315 (for caffeine analysis) and 188 091 (tea and coffee analysis) participants free of any cardiometabolic diseases at baseline from the UK Biobank; 168 metabolites were measured among 88 204 and 96 393 participants. CM was defined as the coexistence of at least 2 of the following conditions: type 2 diabetes, coronary heart disease, and stroke. Nonlinear inverse associations of coffee, tea, and caffeine intake with the risk of new-onset CM were observed. Compared with nonconsumers or consumers of less than 100 mg caffeine per day, consumers of moderate amount of coffee (3 drinks/d) or caffeine (200-300 mg/d) had the lowest risk for new-onset CM, with respective hazard ratios (95% CIs) of 0.519 (0.417-0.647) and 0.593 (0.499-0.704). Multistate models revealed that moderate coffee or caffeine intake was inversely associated with risks of almost all developmental stages of CM, including transitions from a disease-free state to single cardiometabolic diseases and subsequently to CM. A total of 80 to 97 metabolites, such as lipid components within very low-density lipoprotein, histidine, and glycoprotein acetyls, were identified to be associated with both coffee, tea, or caffeine intake and incident CM. Habitual coffee or caffeine intake, especially at a moderate level, was associated with a lower risk of new-onset CM and could play important roles in almost all transition phases of CM development. Future studies are warranted to validate the implicated metabolic biomarkers underlying the relation between coffee, tea, and caffeine intake and CM.

Acute caffeine administration impaired spatial working memory in habitual coffee/tea drinkers: A randomized, placebo-controlled, double-blind study

BackgroundAlthough coffee consumption is widespread worldwide, a recent study showed that acute intake of caffeine negatively affects working memory (WM) performance on n-back tasks among habitual caffeine consumers. However, there is a scarcity of double-blind, placebo-controlled studies that assess the spatial WM (SWM) effects of caffeine using spatial span tasks. Therefore, the present study aimed examine the effects of acute caffeine administration (200 mg, PO) on SWM and verbal WM (VWM) among habitual caffeine consumers. MethodsThe effects of caffeine on working memory (WM) was evaluated through the administration of backward digit span and spatial span tasks under a delay-dependent condition (0, 4, 8, and 6 s) in a randomized, double-blind, placebo-controlled study involving 18 healthy participants. This data is derived from our previous published study. The total scores obtained and the maximum scores achieved were the primary outcome variables of the study. ResultsCaffeine had a significant impact on SWM (maximum obtained, p = 0.013; for total scored, p = 0.007) in a delay-independent manner. However, there were no significant main effects of caffeine on VWM (p = 0.82 for maximum obtained, p = 0.56 for total scored). ConclusionOverall, the present findings contradict the commonly held belief that caffeine improves cognitive performance and suggest that acute administration of caffeine may impair SWM in habitual coffee/tea drinkers. Clinical Trial Registration NumberCT-2018-CTN-02561 (Therapeutic Goods Administration Clinical Trial Registry) and ACTRN12618001292268 (The Australian New Zealand Clinical Trials Registry)

Utilizing Bladder Diaries to Prevent Unnecessary Treatment in Patients With Storage Dysfunction: A Retrospective Study.

Introduction A frequency volume chart (FVC) or bladder diary (BD) is used to diagnose lower urinary tract symptoms and to determine the effectiveness of treatment. In outpatient practice, patients who use an FVC or BD may experience improvement in storage symptoms and not desire further treatment. The aim of this study was to determine the characteristics of patients who did not desire treatment after BD recording and to assess the changes in storage symptoms after BD recording. Methods This was a retrospective study. Patients who completed a three-day BD record were included. The patients were divided into two groups: those whose symptoms improved after using a BD and no longer desired treatment, and those who desired treatment. We compared endpoints including patient background, BD, Overactive Bladder Symptom Score (OABSS), and International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF) score. Results We recruited 79 patients. Four patients were excluded (two were minors and two due to cognitive impairment). Thus, 75 patients were included in the analysis. Of these, 27 (36.0%) did not desire treatment for storage symptoms after BD recording. Compared with the group of patients who desired treatment, those who did not desire treatment had significantly lower daytime and nighttime frequency and number of leaks recorded in their BD, and there were fewer patients with nocturia and habitual caffeine consumption. Baseline OABSSand ICIQ-UI SFscores were lower and there were no significant changes in storage symptoms after BD recording. The cut-off value for the baseline total score of OABSSthat did not desire treatment for storage symptoms after BD recording was 6 points. Conclusion In this study, 36.0% of patients no longer desired treatment for storage symptoms after using a BD. These patients initially exhibited a normal daily urinary frequency and mild storage symptoms. These findings suggest that among patients presenting to the outpatient clinic with storage symptoms, those with mild symptom severity and a total OABSSof 6 points or less may be able to avoid unnecessary treatment through BD recording.

The Effects of Caffeine on Blood Platelets and the Cardiovascular System through Adenosine Receptors.

Caffeine is the most popular and widely consumed behaviourally active substance in the world. This review describes the influence of caffeine on the cardiovascular system, with a special focus on blood platelets. For many years, caffeine was thought to have a negative effect on the cardiovascular system mainly due to increasing blood pressure. However, more recent data suggest that habitual caffeine consumption may reduce the risk of cardiovascular disease and hypertension. This could be a significant finding as cardiovascular disease is the leading cause of death worldwide. Caffeine is known to inhibit A1 adenosine receptors, through which it is believed to modulate inter alia coronary blood flow, total peripheral resistance, diuresis, and heart rate. It has been shown that coffee possesses antiplatelet activity, but depending on the dose and the term of its use, caffeine may stimulate or inhibit platelet reactivity. Also, chronic exposure to caffeine may sensitize or upregulate the adenosine receptors in platelets causing increased cAMP accumulation and anti-aggregatory effects and decrease calcium levels elicited by AR agonists. The search for new, selective, and safe AR agonists is one of the new strategies for improving antiplatelet therapy involving targeting multiple pathways of platelet activation. Therefore, this review examines the AR-dependent impact of caffeine on blood platelets in the presence of adenosine receptor agonists.

Relationship of sociodemographic and clinical characteristics to mechanical restraint used in a psychiatric hospital in Spain.

Coercive measures have been applied in mental health fields throughout history, denying people with mental illness the ability to decide, even though there is increasing evidence that these measures bring few benefits to these individuals. The objective of this study was to analyse the sociodemographic and clinical characteristics most likely associated with the use of mechanical restraints (MRs) in psychiatric hospital settings. This was a descriptive, comparative and analytical cross-sectional study in people with mental disorders who were hospitalized in two hospitals in the Autonomous Valencian Community (Spain). We included a total of 91 participants who completed the Scale to Assess Unawareness of Mental Disorder (SUMD), Positive and Negative Syndrome Scale (PANSS), Barrat's Impulsiveness Scale and the Hamilton Anxiety Scale. The results we collected indicated that the patients most likely to be mechanically restrained were younger people with less awareness of their symptoms and disease, previous admissions to a psychiatric hospital and cohabitation with parents and/or family. In addition, having been admitted involuntarily, previously having had MRs applied, presenting more positive psychotic symptoms and habitual caffeine consumption all predicted the use of MRs. The variables that were able to predict MR were involuntary admission, previous use of MR, the presence of positive psychotic symptoms and caffeine consumption. Evaluation of the sociodemographic and clinical characteristics of patients can help health professionals, especially nurses, to recognize patients who are at risk of requiring MR. This allows mental health practitioners to take these factors into account during interventions or when implementing programmes designed to reduce the use of coercive measures in psychiatric hospital settings. What problem did the study address? Coercive measures have been applied in mental health fields throughout history, with no benefits to these patients. What were the main findings? There are studies that relate some variables to MR in psychiatric settings, but we have been able to find variables capable of predicting MR such as involuntary admission, previous use of MR, the presence of positive psychotic symptoms and caffeine consumption. Where and on whom will the research have an impact? The findings of this study allow for the reduction of MRs in psychiatric units. The sociodemographic and clinical characteristics found to be related to MR will help professionals identify when a patient is admitted in order to use specific interventions aimed at preventing the use of MRs during admission. This is the first study to indicate a relationship between caffeine consumption and the use of MRs. Further studies will be necessary to verify if controlled caffeine supplementation during admission to psychiatric units could become an additional strategy contributing to preventing the application of MR specifically in individuals who habitually consume coffee or caffeine-containing beverages daily. We have adhered to relevant EQUATOR guidelines using the STROBE reporting method. No patient or public contribution.

Habitual Caffeine Use Is Associated With Heightened Cortisol Reactivity to Lab-Based Stress in Two Samples.

Habitual caffeine consumption protects against depression but through unclear mechanisms. Although habitual caffeine use predicts cortisol release in response to other acute stressors (e.g., exercise), this is less examined with lab-based psychosocial stress in healthy adults. Furthermore, caffeine-induced cortisol increases may mask theory-predicted cortisol blunting to robust stress in people with elevated depression risk. In two samples, we tested whether acute (same-day) and habitual caffeine use would predict greater cortisol reactivity to lab-based stress, and whether caffeine would "mask" the effect of a depression risk factor, trait rumination, on blunted cortisol reactivity. In sample 1, N = 128 emerging adults completed one of three Trier Social Stress Test conditions: nonevaluative control, ambiguously evaluative intermediate, or explicit negative evaluative. In sample 2, N = 148 emerging adults completed either a control or negative evaluative condition. In both samples, multilevel growth curve modeling indicated that habitual caffeine use ( t = -1.99, p = .048; t = -2.73, p = .007, samples 1 and 2, respectively) but not acute caffeine use predicted heightened cortisol reactivity as a function of condition. In sample 1, the relationship between condition, rumination, and blunted cortisol was evident only in caffeine nonusers, which differed from users ( t = 2.82, p = .005), but in sample 2, the predicted blunting pattern was evident regardless of caffeine use. The results provide evidence that habitual caffeine use is associated with greater cortisol release under psychosocial lab-based stress and may mask the influence of psychosocial variables; future research should examine whether habitual caffeine-induced cortisol release has behaviorally activating effects that protect against depression.

Common questions and misconceptions about caffeine supplementation: what does the scientific evidence really show?

Caffeine is a popular ergogenic aid that has a plethora of evidence highlighting its positive effects. A Google Scholar search using the keywords "caffeine" and "exercise" yields over 200,000 results, emphasizing the extensive research on this topic. However, despite the vast amount of available data, it is intriguing that uncertainties persist regarding the effectiveness and safety of caffeine. These include but are not limited to: 1. Does caffeine dehydrate you at rest? 2. Does caffeine dehydrate you during exercise? 3. Does caffeine promote the loss of body fat? 4. Does habitual caffeine consumption influence the performance response to acute caffeine supplementation? 5. Does caffeine affect upper vs. lower body performance/strength differently? 6. Is there a relationship between caffeine and depression? 7. Can too much caffeine kill you? 8. Are there sex differences regarding caffeine's effects? 9. Does caffeine work for everyone? 10. Does caffeine cause heart problems? 11. Does caffeine promote the loss of bone mineral? 12. Should pregnant women avoid caffeine? 13. Is caffeine addictive? 14. Does waiting 1.5-2.0 hours after waking to consume caffeine help you avoid the afternoon "crash?" To answer these questions, we performed an evidence-based scientific evaluation of the literature regarding caffeine supplementation.

Acute effects of energy drink on arterial stiffness and endothelial function in young male bodybuilders with habitual caffeine consumption

Elite bodybuilders consume energy drink (ED) immediately before or during strength training. However, the effects of ED on cardiovascular responses have not been fully understood. In this study, the carotid-femoral pulse wave velocity (cfPWV) and flow-mediated dilation (FMD), which are indices of arterial stiffness and endothelial function in response to acute ED consumption, were examined. Forty-five young men (30.0 ± 3.9 years) were investigated: sedentary (CON, n = 15), physically active (PA, n = 15), and bodybuilders (BD, n = 15). After they consumed commercial ED, their vascular function was analyzed at the following time points: pre, post, 30 min and 60 min. At baseline, the age, height and systolic and diastolic blood pressure of the groups did not significantly differ; conversely, their weight, body mass index, lean mass, fat percent and grip strengths significantly differed (p &lt; 0.05). After ED consumption, central and peripheral blood pressure markedly increased in the PA and CON groups (p &lt; 0.05) but not in the BD group. cfPWV, augmentation index and wave reflection were not different among the groups and did not change at any time point (p &gt; 0.05). However, FMD notably differed among the groups after ED consumption. The FMD of the BD group increased sharply and significantly after ED consumption at post-time points (pre, 6.5% ± 1.7%; post, 13.1% ± 2.6%; 30 min, 10.7% ± 2.9%; 60 min, 8.9% ± 2.4%, p = 0.001). The FMD markedly increased after ED consumption in the PA group (p = 0.004), but it did not change in the CON group (p &gt; 0.05). ED consumption acutely triggered the increase in endothelial function in the BD and PA groups. Therefore, these findings helped elucidate the distinct cardiovascular responses to ED intake among different populations with varying physical activity or training levels.

Genome-wide Association Study of Caffeine Consumption Using Coriell Personalized Medicine Collaborative Data

More than 90% of Americans consume caffeine daily, but the amount consumed varies widely. Previous studies have shown that genes related to caffeine metabolism and receptor binding may influence caffeine consumption. A better understanding of the relationship between genotype and caffeine consumption has the potential to inform mechanisms of this common dietary behavior. We performed a genome-wide association study (GWAS) of self-reported consumption data combining a wide range of caffeinated beverages including coffee, tea, soda, and energy drinks in the Coriell Personalized Medicine Collaborative (N=2,830) using a generalized linear model. Our analysis identified several candidate loci implicated in caffeine consumption. One previously identified SNP associated with caffeine consumption and replicated in the current study, rs2472297 (P-value=3.8x10-6), is located in an intergenic region between CYP1A1 and CYP1A2 (the gene that encodes the enzyme primarily responsible for caffeine metabolism), and has been associated with caffeine consumption in prior studies. Our results further support follow-up functional studies focused on the role of CYP1A1 and CYP1A2 on caffeine consumption habits, metabolism, and health status and outcomes.

Prevalence of caffeine-dependent students in the electromechanical engineering program at Universidad Technical Equinoctial

Caffeine consumption is a common practice among university students to cope with academic demands. This study aimed to determine the prevalence of caffeine-dependent students in the Electromechanical Engineering program at the Technical University Equinoccial of Ecuador. A non-experimental and descriptive design was used. Surveys were conducted with 156 students to assess their caffeine consumption habits, product preferences, and knowledge of its effects. The results indicated that 40.4% of the students consume caffeine daily, and 84.6% have a low level of knowledge about its consequences. The prevalence of consumption was higher among men, although women showed a higher tendency in percentage terms. The study concludes the need to implement educational and awareness strategies on responsible caffeine consumption and its health risks, and thus an educational and preventive proposal is made to the institution subject of this study

ASSOCIATION BETWEEN CAFFEINE, ANXIETY AND THE OCCURRENCE OF APHTHOUS STOMATITIS IN THE ARMENIAN ETHNICITY

Abstract Introduction: Aphthous stomatitis is a recurring oral ulceration condition that affects a significant proportion of the population. While several factors have been proposed to contribute to its occurrence, the link between caffeine consumption, anxiety levels, and the development of aphthous stomatitis remains unknown. This survey-based study aimed to understand the association between coffee, anxiety, and the development of aphthous stomatitis in this specific demographic, which can provide useful insights for medical management as well as preventive strategies. Material and methods: A structured online questionnaire was distributed via various social media platforms targeting a sample of the Armenian population. The questionnaire collected information on participants’ demographics, coffee use patterns, anxiety levels as measured by perceived stress scales, and the occurrence of aphthous stomatitis. Statistical analyses, including Kendall’s tau, were carried out to investigate the relationships. Results: The results revealed a significant negative association between caffeine consumption and the occurrence of aphthous stomatitis among Armenian individuals Kendall’s tau-b (τb) correlation - 240* (p&lt;0.05). Participants who reported regular caffeine consumption, such as coffee, tea, and energy drinks, had a lesser prevalence of aphthous stomatitis than non-consumers. Furthermore, Armenians in the survey showed that the majority (83.5%) had a low to moderate stress level. Conclusion: The data we collected in our research indicate that the prevalence of Recurrent Aphthous Stomatitis in the Armenian ethnicity was infrequent; over half of the participants didn’t report Recurrent Aphthous Stomatitis in the past 12 months. Which may correlate to their caffeine consumption habits, which can lead to stress reduction.

Secondary School Students and Caffeine: Consumption Habits, Motivations, and Experiences.

Adolescents may be particularly vulnerable to the effects of caffeine due to a lack of tolerance, their small size, changing brain physiology, and increasing independence. Concerns about adolescent caffeine consumption relate to potentially serious physiological and psychological effects following consumption. Motivations driving caffeine intake are not well understood among adolescents but are important to understand to reduce harmful behavioural patterns. This study explored caffeine consumption habits (sources, amount, frequency) of New Zealand adolescents; and factors motivating caffeine consumption and avoidance. The previously validated caffeine consumption habits questionnaire (CaffCo) was completed by 216 participants (15-18 years), with most (94.9%) consuming at least one caffeinated product daily. Chocolate, coffee, tea, and kola drinks were the most consumed sources. The median caffeine intake was 68 mg·day-1. Gender (boy) and being employed influenced the source, but not the quantity of caffeine consumed. One-fifth (21.2%) of adolescents consumed more than the recommended European Food Safety Authority (EFSA) safe level (3 mg·kg-1·day-1). Taste, energy, and temperature were the main motivators for consumption, and increased energy, excitement, restlessness, and sleep disturbances were reported effects following caffeine consumption. This study provides information on caffeinated product consumption among New Zealand adolescents, some of whom consumed caffeine above the EFSA safe level. Public health initiatives directed at adolescents may be important to reduce potential caffeine-related harm.

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.

Caffeine and Team ball performances: A Mini-Review

Background: Caffeine is the most consumed psychoactive substance globally, second only to water in beverage consumption. Its impact on athletic performance, particularly in team sports, has been a subject of growing research interest. This review focuses on recent studies investigating caffeine's influence on various aspects of team ball sports performance. Objectives: This mini-review aimed to (i) synthesize current research findings on caffeine supplementation in team sports, considering different doses, forms, and its effects across genders and (ii) to highlight key considerations for optimal caffeine use in these sports. Methods: THIS mini-review examined recent studies on caffeine's effects in team ball sports, analyzing variables such as supplementation strategies, habitual consumption, gender, washout periods, individual responses, and supplement forms (capsules or powders). The focus is on studies that have used caffeine doses ranging from 3 to 6 mg·kg -1, administered 60 minutes before competition. Results: Findings suggest beneficial effects of caffeine ingestion (3 to 6 mg·kg-1) in enhancing technical and physical aspects of team ball sports. However, results vary based on factors like the supplementation strategy, individual caffeine consumption habits, and gender. Most research has focused on single-dose effects, revealing a lack of comprehensive, gender-specific guidelines for caffeine's optimal use in team sports. Conclusion: While caffeine supplementation shows promise in enhancing team sports performance, there is a need for more comprehensive research, especially regarding gender-specific effects and optimal consumption strategies. Current evidence points to the potential benefits of caffeine in morning competitions or training sessions but indicates possible detrimental effects in afternoon or evening settings. Further research is needed to develop robust guidelines for caffeine use in team sports, considering dosage, timing, form, and differential gender effects.

Assessment of caffeine consumption behavior among Jazan University students in the south of Saudi Arabia: A cross-sectional study

Caffeine is a central nervous system stimulant. High consumption levels of caffeine can lead to intoxication and serious side effects. Saudi Arabia is witnessing a rise in the commercialization and consumption of caffeine. Young adults such as university students may exhibit high levels of caffeine consumption. This investigation aims to assess caffeine consumption habits among a sample of Jazan University students in the south of Saudi Arabia. This study was a cross-sectional investigation that utilized multistage sampling to recruit the students. Data was collected via a self-administered questionnaire that measured student demographics, their frequency of consuming caffeine-containing food, portion sizes, and patterns of consumption during different times of the day. Caffeine consumption levels were estimated based on a cutoff point of 400 mg per day. A chi-squared test was used to investigate the association between levels of caffeine consumption and measured study characteristics. A sample of 964 students was recruited with a mean age of 21.8 years. The most frequently consumed product among the recruited students was coffee (32%), followed by chocolate bars (16%) and soft drinks (12%). The median total consumed caffeine amount was 185 mg per day. 194 (20%) students of the sample exceeded the recommended level of daily caffeine consumption (>400 mg/day). Among the measured demographics, only the year of study was associated with caffeine consumption (P value of .003), suggesting that students in their earlier years of university are likely to exceed the recommended daily consumption of caffeine in comparison with those who are in their later years of study. Our investigation identified high levels of caffeine consumption among some students. The findings imply the need to enhance the awareness of students who exceed the recommended daily intake of caffeine regarding the harmful impacts of caffeine toxicity.

Variability of caffeine content in green and roasted Coffea arabica regarding the origin, post-harvest processing, and altitude, and overview of recommended daily allowance

Caffeine content is a crucial attribute of coffee. Its concentration and thus maximum cups of Coffea arabica from Africa, Asia, Central America, and South America from different altitudes of growing areas, altitude, and process using different post-harvest processing (dry, wet, and pulped natural). Our results suggest that geographical origin might affect the alkaloid concentration in C. arabica. The caffeine concentration pattern in green samples was as follows: Central America > South America > Asia > Africa. Altitude affected the concentrations, lowlands > midlands > highlands, however, not significantly. Given caffeine is thermostable, the medium roasting process did not affect the concentration of caffeine directly, but a small increase was observed. Scientific opinion on the safety of habitual caffeine consumption of up to 400 mg per day does not raise safety concerns for non-pregnant adults. A cup (7 g coffee in 120 mL of water) was used for recalculation. Results suggest that mostly highlands and midlands coffee from Africa reached levels of caffeine that might be consumed in more than 5.5 cups a day.

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.

The characteristics of caffeine intake in Croatian university students

Abstract Background Excessive caffeine intake combined with increasing numbers and availability of caffeine-containing products in modern societies are causes for concern. University students may be at increased risk of excessive caffeine consumption due to seeking caffeinated products with well-known wakefulness effects and cognitive benefits. This study aimed to highlight the characteristics of caffeine consumption among Croatian university students. Methods This cross-sectional questionnaire study was conducted from May 2020 to April 2021 period. A validated, anonymous questionnaire that contained questions regarding demographic data, data about caffeine consumption habits, and its sources was self-administered via an online link to a cross-faculty representative student sample of the University of Osijek in Eastern Croatia. Results The study sample included 1197 subjects with, median age of 22 years (interquartile range 21-24), 24.1% males, and 75.9% females. The median caffeine intake was 512.0 mg/day (interquartile range 228.0-972.0). The higher caffeine intake was observed in part-time students (p = 0.026), students who were preparing for exams during the participation in this study (p = 0.010), and students who smoked cigarettes (p &amp;lt; 0.001). There was a poor positive correlation between the amount of caffeine intake and academic success connected with caffeine consumption (rs = 0.225; p &amp;lt; 0.001). There were fair positive correlations between the amount of caffeine intake and caffeine consumption because of the avoidance of the withdrawal symptoms (rs = 0.490; p &amp;lt; 0.001) and between the amount of caffeine intake and knowledge of the impact of caffeine consumption on the occurrence of social conflicts (rs = 0.349; p &amp;lt; 0.001). Conclusions The study revealed high caffeine intake among Croatian university students. The implementation of specific preventive measures directed toward the protection of students’ health from adverse health effects related to caffeine is needed. Key messages • Croatian university students have displayed high caffeine intake in their everyday life. • There is a need for the implementation of specific preventive measures directed toward the protection of students’ health from adverse health effects related to caffeine consumption.

Reply to Zhang and Chen’s Comment on “Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine”

Reply to Zhang and Chen’s Comment on “Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine”