Associations between nutritional adequacy and insomnia symptoms in Japanese men and women aged 18-69 years: a cross-sectional study

The Prevalence of Insomnia Disorder in the General Population: A Meta-Analysis

Insomnia disorder is a significant public health issue, but the prevalence estimates vary widely. We performed a meta-analysis aiming to pool prevalence rates in studies (1) carried out in the general population (2) using a true random sample (3) and using a diagnostic interview, DSM based self-report questions, or a questionnaire with a cut-off established against the DSM criteria. A literature search (in PubMed, Embase, APA PsycInfo) was performed up to April 2024. Two independent reviewers assessed title and abstracts (n = 6732), full-text manuscripts (n = 621) and extracted the data of the 47 included studies. Prevalence rates were pooled using a three-level hierarchical random-effects model, stratified by diagnosis type and adjusted for gender distribution and mean sample age. The pooled prevalence of all studies using an interview to establish the DSM criteria was 12.4% (95% CI: 9.0-16.8%), and of self-report questions assessing the DSM diagnosis 16.3% (95% CI: 11.3%-23.0%). There were 27 studies using different insomnia questionnaires with different cut-offs (prevalence range 7.5%-32.3%). The prevalences differed significantly across regions and high quality studies yielded a lower prevalence rates than lower quality studies. This meta-analysis confirms that insomnia is a common disorder with a prevalence of 12.4 as the most accurate estimate. It also shows the need for standardised ways of assessing insomnia. We think the golden standard is using standardised structured clinical interviews. However, if this is not feasible, we recommend using well validated questionnaires such as the Sleep Condition Indicator or the Insomnia Severity Index. Trial Registration: PROSPERO CRD42023402745.

The Association Between Dietary Vitamin C and Sleep Disorders: A Cohort Study Based on UK Biobank

Objective: Approximately 30% of adults globally suffer from sleep disorders. However, there are few longitudinal studies on the association between dietary vitamin C and sleep disorders. This study aimed to investigate the association between dietary vitamin C intake and various types of sleep disorders, including sleep apnea and insomnia. Methods: We enrolled 68,221 participants from the UK Biobank. Dietary vitamin C intake was assessed using a 24 h dietary recall questionnaire. We employed a Cox regression model to assess the association between dietary vitamin C and sleep disorders and used restricted cubic spline models to investigate potential nonlinear relationships. Stratified and sensitivity analyses were also conducted to validate the findings. Results: The results indicated that vitamin C intake at the Q4 level (132.88-191.51 mg/d) was significantly associated with a reduced risk of sleep disorders, with an HR (95% CI) of 0.78 (0.65-0.94), and against sleep apnea, with an HR (95% CI) of 0.75 (0.62-0.92). The protective effect persisted significant in stratified analyses of men and those aged ≤ 60 years; the results were consistent in the sensitivity analyses. Conclusions: Our findings suggest that sufficient dietary vitamin C intake may help to prevent sleep disorders.

Dietary patterns and insomnia symptoms: A systematic review and meta-analysis

We aimed to systematically review and synthesize the available evidence regarding the link between dietary patterns and insomnia symptoms among the general population using observational studies. We reviewed 16,455 references, of which 37 studies met inclusion criteria with a total sample size of 591,223. There was a significant association of the Mediterranean diet (OR: 0.86; 95 % CI, 0.79, 0.93; P < 0.001; I2 = 32.68 %), a high-quality diet (OR: 0.66; 95 % CI, 0.48, 0.90; P = 0.010; I2 = 84.62 %), and an empirically-derived healthy dietary pattern (OR: 0.91; 95 % CI, 0.85, 0.98; P = 0.010; I2 = 57.14 %) with a decreased risk of insomnia symptoms. Moreover, the dietary glycemic index (OR: 1.16; 95 % CI, 1.08, 1.25; P < 0.001; I2 = 0.0 %), the dietary glycemic load (OR: 1.10; 95 % CI, 1.01, 1.20; P = 0.032; I2 = 74.36 %), and an empirically-derived unhealthy dietary pattern (OR: 1.20; 95 % CI, 1.01, 1.42; P = 0.040; I2 = 68.38 %) were linked with a higher risk of insomnia symptoms. Most individual studies were of good quality (NOS) but provided very low certainty of evidence (GRADE). Consistent data reveals that following healthy diets is associated with decreased insomnia symptoms prevalence, while adherence to an unhealthy pattern is associated with an increased prevalence of insomnia symptoms.

Association between vitamin C in serum and trouble sleeping based on NHANES 2017-2018

Vitamin C is an important micronutrient for human. Association between vitamin C and trouble sleeping was less studied. Therefore, the purpose of this study was to investigate the possible link between vitamin C in serum and trouble sleeping. The cross-sectional data was derived from the National Health and Nutrition Examination Survey (NHANES, 2017-2018). Trouble sleeping was measured by asking participants: "Have you ever told doctor had trouble sleeping". Responses to this question was "yes" or "no". vitamin C in serum was obtained by measuring the serum samples. We used multivariable binary logistic regressions to examine the possible link between vitamin C in serum and trouble sleeping, and then a subgroup analysis was performed. Moreover, the non-linear relationship between vitamin C in serum and trouble sleeping was further detected using a restricted cubic spline (RCS) model. A total of 3227 participants were included in the study. After adjusting all potential confounders, the results of multivariable logistic regression showed the significant negative association between vitamin C in serum and trouble sleeping(OR = 0.816; 95% CI:0.669 ~ 0.995). The significant inverse association was also found in female(OR = 0.713; 95% CI:0.546 ~ 0.931), age ≤ 65 years(OR = 0.773; 95% CI:0.600 ~ 0.996), and in participants with high cholesterol level(OR = 0.738; 95% CI:0.548 ~ 0.994). In addition, the RCS model demonstrated the significant non-linear relationship between vitamin C in serum and trouble sleeping (P value of nonlinear = 0.010). Our study demonstrates the significant negative association between vitamin C in serum and trouble sleeping.

Nutrient Intake from Voluntary Fortified Foods and Dietary Supplements in Japanese Consumers: A Cross-Sectional Online Survey

Consuming voluntary fortified foods (vFFs) and dietary supplements (DSs) is one method for addressing micronutrient inadequacy, but their efficacy is unclear. This study explored the use of vFFs and DSs, and the role of package labels. We conducted a nationwide online survey of 4933 Japanese adults in 2020. The use of vFFs and DSs was 23.3%. The reported vFFs were cereal products (n = 370), milk products/milk substitutes (n = 229), and one-shot drinks (n = 144). Vitamins, calcium, and iron were the main micronutrients added to the vFFs. Most users consumed vitamins C and B from vFFs and/or DSs, and females also consumed iron. The median intake of vitamins B6 and C, selenium, and zinc (plus vitamin B2 and copper in females) exceeded 50% of the respective estimated average requirement values. Approximately 60-70% of the users referred to nutrition labels. However, only a small percent of the respondents clearly understood the nutrient content. To address insufficient nutrient intake, the use of vFFs and DSs may be a good alternative; however, consumer education on the use of vFFs/DSs and package labels needs to be implemented before encouraging their use.

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.

Associations of serum zinc, copper, and selenium with sleep disorders in the American adults: Data from NHANES 2011-2016

BACKGROUND

Even though various studies have been conducted to investigate the relationship between trace metals and sleep, few epidemiological studies have evaluated the relationship between trace metals and sleep disorders in American adults.

OBJECTIVE

This study intended to evaluate the associations of serum zinc (Zn), copper (Cu), selenium (Se), Zn/Cu, Zn/Se, and Cu/Se ratios with sleep disorders in American adults.

METHODS

We conducted a cross-sectional analysis of 3660 adults aged ≥18 years old who participated in the National Health and Nutrition Examination Survey (NHANES) 2011-2016. Binary logistic regression was employed to calculate the odds ratio (OR) and 95 % confidence interval (CI) of either serum trace metals or serum trace metals ratios with risks among sleep disorder phenotypes. The restricted cubic spline (RCS) model was additionally utilized to check the dose-response relationships between serum trace metals, serum trace metals ratios, and sleep disorders.

RESULTS

Logistic regression demonstrated that higher serum Zn (OR: 0.70, 95 % CI: 0.51-0.97, p = 0.035), Zn/Cu (OR: 0.62, 95 % CI: 0.45-0.87, p = 0.007), and Zn/Se (OR: 0.68, 95 % CI: 0.49-0.95, p = 0.025) were related to a decreased likelihood of self-reported sleep disorders, and dose-response relationships were detected by the RCS models, after adjustment for sociodemographic, behavioral, and health characteristics. No associations between serum Cu, Se, Cu/Se, and sleep disorders were observed. The findings in the sensitivity analyses were consistent with these results.

CONCLUSION

Our study revealed that serum Zn, Zn/Cu, and Zn/Se were inversely associated with the risk of self-reported sleep disorders in US adults.

The impact of insomnia on frailty and the hallmarks of aging

Throughout the course of life, there are age-related changes in sleep. Despite these normal changes, there is a high percentage of older adults that report sleep dissatisfaction with a high pervasiveness of chronic insomnia, the most common sleep disorder worldwide, with its prevalence being expected to continuously increase due to the growing rates of aging and obesity. This can have different adverse health outcomes, especially by promoting both physical and cognitive decline, which ultimately may aggravate frailty in older adults. Moreover, age-related frailty and sleep dysfunction may have a common mechanism related to the hallmarks of cellular aging. Cellular aging was categorized into nine hallmarks, such as DNA damage, telomere attrition and epigenetic changes. In the context of geriatric and chronic insomnia research, this review aims at discussing the current evidence from both animal models and human cohorts addressing the link between chronic insomnia, the hallmarks of aging and their impact on frailty. Moreover, the most recent research about the putative effect of insomnia therapeutic approaches on hallmarks of aging will be also highlighted.

Factors associated with insomnia in older adult outpatients vary by gender: a cross-sectional study

Background

Insomnia is a common sleep disturbance in older adults and is associated with many poor health outcomes. This study aimed to explore factors associated with insomnia in older adult outpatient clinics, and to further analyze the influence of gender on factors associated with insomnia.

Methods

This cross-sectional study was conducted in the outpatient clinics of a tertiary hospital in Southern Taiwan from July to September 2018. A total of 400 consecutive subjects aged 60 years or older were recruited. Insomnia was defined as a score of ≥6 points on the Athens Insomnia Scale (AIS). Socio-demographics, health behaviors and clinical data were collected by face-to-face interview. Multivariable logistic regression was adopted for statistical analysis of the entire sample and stratified by gender.

Results

Participants’ mean age was 74.74 ± 8.54 years, and the majority (93%) had more than one chronic disease. The prevalence of insomnia accounted for 30% (120/400) of all subjects, with males 22.9% (46/201) and females 37.2% (74/199). Gender, appetite, exercise, depressive symptoms, and sleep-related conditions such as short sleep duration, sleeping pills usage, medium-high risk of obstructive sleep apnea (OSA) and restless leg syndrome (RLS) were factors associated with insomnia in older adults. Exercise, sleeping pills usage, and RLS were independently associated with insomnia only in men, while appetite and medium-high risk of OSA were associated with insomnia in women only. In addition, after further adjusting for covariates, prevalence of the insomnia-related symptoms such as sleep induction, total sleep duration, sleep quality and sleepiness during the day was significantly higher in females than in males.

Conclusions

Insomnia symptoms are highly prevalent among older adults, predominantly females. Significant differences are found between genders in factors associated with insomnia and insomnia-related symptoms. Understanding gender differences may help clinicians to modify associated factors when managing older adults with insomnia.

Is there a relationship between the ketogenic diet and sleep disorders?

Sleep disorders are very often underestimated and, consequently, not treated with due priority. Common sleep disorders include insomnia disorders, sleep-related breathing disorders, central disorders of hypersomnolence, circadian rhythm sleep-wake disorders, sleep-related movement disorders, parasomnias, and other sleep disorders. The ketogenic diet (KD) is rich in fat, low in carbohydrates (CHO), and adequate in protein. The KD has shown several applications in treating medical conditions, such as epilepsy, neurodegenerative disorders, obesity with its comorbidities, and sleep disorders, with encouraging results. Therefore, the purpose of this review is to address the primary sleep disorders and their respective standard therapeutic approaches, analyse the effect of ketone bodies (KBs) on sleep homeostasis, and the effects of KD on sleep disorders and in particular on obstructive sleep apnoea (OSA) syndrome. The goal is to summarise the evidence existing up to now on the subject, to provide a starting point for further investigations.

Association of Hours of Paid Work with Dietary Intake and Quality in Japanese Married Women: A Cross-Sectional Study

This study investigated the association of hours of paid work with dietary intake and diet quality among Japanese married women. This cross-sectional study was a secondary analysis of a nationwide population survey in 2013. The analytic sample included 644 married women aged 20–59 years. The participants were categorized into five groups according to hours of paid work per week: 0 (housewives), 1–14, 15–34, 35–42, and ≥43 h. Dietary intake was assessed by a self-administered diet history questionnaire. The Nutrient-Rich Food Index 9.3 (NRF9.3) was used to measure the dietary quality. The association of hours of paid work with dietary intake and NRF9.3 score was assessed using a multivariable general linear regression analysis with adjustments for confounders. Hours of paid work were associated with a higher intake of rice and lower intake of vegetables, potatoes, soy products, and seaweeds and nutrients including protein, dietary fiber, and most vitamins and minerals. Hours of paid work were negatively associated with the NRF9.3 score. This study showed that Japanese married women engaging in paid work, especially those who work long hours, have less healthy diets. Efforts to improve the dietary intake of married women with paid work might be needed.

The Role of Vitamin C in Two Distinct Physiological States: Physical Activity and Sleep

This paper is a literature overview of the complex relationship between vitamin C and two opposing physiological states, physical activity and sleep. The evidence suggests a clinically important bidirectional association between these two phenomena mediated by different physiological mechanisms. With this in mind, and knowing that both states share a connection with oxidative stress, we discuss the existing body of evidence to answer the question of whether vitamin C supplementation can be beneficial in the context of sleep health and key aspects of physical activity, such as performance, metabolic changes, and antioxidant function. We analyze the effect of ascorbic acid on the main sleep components, sleep duration and quality, focusing on the most common disorders: insomnia, obstructive sleep apnea, and restless legs syndrome. Deeper understanding of those interactions has implications for both public health and clinical practice.

Cultural and life style practices associated with low inflammatory physiology in Japanese adults

Japan is an exceptionally healthy East Asian country with extended longevity. In addition, the typical levels of several proinflammatory proteins, including both C-reactive protein (CRP) and interleukin-6 (IL-6), are often reported to be low when compared to American and European populations. This analysis determined if blood levels of CRP and IL-6 were associated with 4 cultural practices reflective of Japanese behavior and customs -- drinking tea, eating seafood, consuming vegetables, and partaking in relaxing baths regularly - among 382 adults living in Tokyo. Regression models controlled for demographic factors, adiposity (BMI), physical exercise, smoking, alcohol use, and chronic illness (e.g., diabetes). Consuming a Japanese diet was associated with significantly lower CRP and IL-6 levels. More frequent bathing was associated with lower IL-6, but not specifically predictive of low CRP. This study has confirmed prior evidence for low inflammatory activity in Japanese adults and its association with several behavioral practices common in Japan.