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BACKGROUND Previous studies have only investigated how symptom presentation and socio-demographic factors influence care-seeking for low back pain (LBP). However, the influence of health and lifestyle factors remains unclear, and the potential confounding effects of aggregated familial factors (including genetics and the early shared environment) has not been considered extensively. METHODS A cross-sectional analysis was performed on 1605 twins enrolled in the Murcia Twin Registry (Spain). The outcome was seeking medical care for LBP and various self-reported demographic, health and lifestyle factors were considered predictors. All variables except sleep quality and diabetes were collected in 2013, which were cross-referenced from 2009 to 2010. A multivariate logistic regression model was performed on the total sample, followed by a co-twin case-control analysis. RESULTS The only significant factor found to increase the odds of seeking medical care for LBP without being affected by familial factors was poor sleep quality (total sample OR = 1.58, 95%CI 1.24-2.01; case-control OR = 1.75, 95%CI 1.14-2.69). The factors that were associated with reduced odds of seeking medical care for LBP and not confounded by familial factors were male sex (case-control OR = 0.55, 95%CI 0.33-0.93), alcohol intake (case-control OR = 0.90, 95%CI 0.82-0.99) and a history of diabetes (case-control OR = 0.50, 95%CI 0.25-0.97). No other factors significantly influenced medical care-seeking for LBP. CONCLUSIONS People reporting poor sleep quality are more likely to seek medical care for LBP in the long term, with this relationship being independent from aggregated familial factors. Conversely, males, people reporting higher alcohol intake, and people with a history of diabetes are less likely to seek medical care for LBP. SIGNIFICANCE This is the first study investigating the factors that influence seeking medical care for LBP, while adjusting for the influence of familial factors using a co-twin control design. Poor sleep quality is associated with seeking medical care for LBP in the long term and does not appear to be confounded by familial factors. Early screening for indicators of poor sleep quality and appropriate referral to interventions for improving sleep quality or reducing pain in sleep may improve LBP management.

BackgroundSleep apnea is one of the most common sleep disorders and it is related to multiple negative health consequences. Previous studies have shown that sleep apnea is influenced by genetic factors. However, studies have not investigated the genetic and environmental influences of symptoms of sleep apnea in young adults. Furthermore, the underpinnings of the relationship between apnea symptoms and internalizing/externalizing problems are unknown. The objectives of this study were to estimate the magnitude of: (1) genetic and environmental influences on self-reported apnea symptoms; (2) the relationship between self-reported apnea symptoms and internalizing/externalizing traits; (3) genetic and environmental influences on the associations between self-reported apnea symptoms, internalizing behaviors and externalizing behaviors.MethodsIn a twin/sibling study, univariate and multivariate models were fitted to estimate both individual variance and sources of covariance between symptoms of sleep apnea and internalizing/externalizing behaviors.ResultsOur results show that genetic influences account for 40% of the variance in sleep apnea symptoms. Moreover, there are modest associations between depression, anxiety and externalizing behaviors with apnea symptoms (ranging from r = 0.22–0.29). However, the origins of these associations differ. For example, whereas most of the covariation between symptoms of depression and sleep apnea can be explained by genes (95%), there was a larger role for the environment (53%) in the association between symptoms of anxiety and sleep apnea.ConclusionsGenetic factors explain a significant proportion of variance in symptoms of apnea and most of the covariance with depression.

Study Objectives Twin studies have provided data about the relative weight of genetic and environmental factors on sleep variables over the last few decades. However, heritability is a non-intuitive concept and it is often misunderstood even amongst the scientific community. This study aimed to analyze: (1) understanding of the meaning of heritability of insomnia; (2) the accuracy of estimations of heritability in the general population regarding three sleep traits (sleep duration, sleep quality and insomnia); (3) perceptions of the effectiveness of different treatments for insomnia depending on how the disorder is presented (i.e. having an environmental or genetic etiology) and whether the subject’s estimate of genetic influence on sleep traits impacted beliefs about the effectiveness of different treatments. Methods Participants (N = 3658) completed a survey which included: questions about general genetic knowledge; a specific question about the meaning of heritability; estimates of heritability of three different sleep traits; and the effectiveness of different treatments for insomnia depending on how the etiology of this condition was presented. Results Fewer than 25% of the participants selected the correct description of the heritability of insomnia. Almost half of the sample incorrectly believed that heritability refers to the chance of passing a disorder onto their children. We also found that participants provided different estimates for the effectiveness of different treatments depending on the presumed etiology of the disorder. Conclusion Most people do not have accurate knowledge about the concept of heritability. People’s assumptions about the etiology of a disorder may influence which treatments they consider most effective. J.J.M-V. was supported by predoctoral scholarship (19814/FPI/15) of the Fundación Seneca. This work was supported by Russian Foundation for Basic Research Grant No. 18-29-14071.

The last decades have witnessed a sudden increase in myopia incidence among youngsters that have been related to modern lifestyle along with the use of emerging technologies affecting visual exposure. Increasing exposures to known risk factors for myopia, such as time spent indoors, close-distance work, or low-light conditions are thought to be responsible for this public health issue. In most cases, development of myopia is secondary to a vitreous chamber enlargement, although the related mechanisms and the potential interaction between central and peripheral retinal area remain unclear. For a better understanding, we performed a classical twin study where objective refractive error along 70° of horizontal retinal arc was measured in 100 twin pairs of university students, 78% of which showed manifest myopia. We found the variance of shared environmental origin (range 0.34 to 0.67) explained most of the objective refractive error variance within central 42° of the retina (22° temporal to 19° nasal), whereas additive genetic variance (range 0.34 to 0.76) was predominant in the peripheral retinal areas measured. In this sample of millennial university students, with a large prevalence of myopia, environmental exposures were mostly responsible for inter-individual variation in the retinal horizontal area surrounding the macula, while their relative weight on phenotypic variance was gradually descending, and replaced by the variance of genetic origin, towards the retinal periphery. This study was supported by MyFUN (Myopia Fundamental Understanding Needed): European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 675137.

Background The use of technology and social media among adolescents is an increasingly prevalent phenomenon. However, there is a paucity of evidence on the relationship between frequency of use of electronic devices and social media and sleep-onset difficulties among the Italian population. Objective The aim of this study is to investigate the association between the use of technology and social media, including Facebook and YouTube, and sleep-onset difficulties among adolescents from Lombardy, the most populous region in Italy. Methods The relationship between use of technology and social media and sleep-onset difficulties was investigated. Data came from the 2013-2014 wave of the Health Behavior in School-aged Children survey, a school-based cross-sectional study conducted on 3172 adolescents aged 11 to 15 years in Northern Italy. Information was collected on difficulties in falling asleep over the last 6 months. We estimated the odds ratios (ORs) for sleep-onset difficulties and corresponding 95% CIs using logistic regression models after adjustment for major potential confounders. Results The percentage of adolescents with sleep-onset difficulties was 34.3% (1081/3151) overall, 29.7% (483/1625) in boys and 39.2% (598/1526) in girls. It was 30.3% (356/1176) in 11-year-olds, 36.2% (389/1074) in 13-year-olds, and 37.3% (336/901) in 15-year-olds. Sleep-onset difficulties were more frequent among adolescents with higher use of electronic devices, for general use (OR 1.50 for highest vs lowest tertile of use; 95% CI 1.21-1.85), use for playing games (OR 1.35; 95% CI 1.11-1.64), use of online social networks (OR 1.40 for always vs never or rarely; 95% CI 1.09-1.81), and YouTube (OR 2.00; 95% CI 1.50-2.66). Conclusions This study adds novel information about the relationship between sleep-onset difficulties and technology and social media in a representative sample of school-aged children from a geographical location that has not been included in studies of this type previously. Exposure to screen-based devices and online social media is significantly associated with adolescent sleep-onset difficulties. Interventions to create a well-coordinated parent- and school-centered strategy, thereby increasing awareness on the unfavorable effect of evolving technologies on sleep among adolescents, are needed.

Nonpharmacological treatment of insomnia in older persons has been associated with reduced insomnia symptoms and increased psychological wellbeing. This systematic review and meta-analysis examined whether nonpharmacological interventions can promote wellbeing indicators in older persons who experience insomnia symptoms and investigated the components of these interventions. Twenty studies met inclusion criteria. Psychological wellbeing outcomes included symptoms of depression, anxiety, mental health-related quality of life, and fatigue. Interventions significantly reduced depression and fatigue symptoms in most of the studies that included these outcomes. Findings of our qualitative analysis suggest that mindfulness-based interventions in particular can potentially reduce depression symptoms in older persons with insomnia symptoms. Meta-analyses of studies that included psychological wellbeing outcomes showed small-medium weighted mean effects indicating reductions in symptoms of depression, anxiety, and fatigue. The results suggest that nonpharmacological interventions for older persons with insomnia symptoms can potentially reduce depression and fatigue symptoms and highlight interventions that may be particularly valuable for this purpose.

Resumen Los diseños genéticamente informativos, y en particular los estudios de gemelos, constituyen la metodología más utilizada para analizar la contribución relativa de los factores genéticos y ambientales a la variabilidad interindividual. Básicamente, consisten en comparar el grado de similitud, con respecto a una característica o rasgo determinado, entre gemelos monocigóticos y dicigóticos. Además de la clásica estimación de heredabilidad, este tipo de registros permite una amplia variedad de análisis únicos por las características de la muestra. El Registro de Gemelos de Murcia es un registro de base poblacional centrado en el análisis de conductas relacionadas con la salud. Las prevalencias de problemas de salud observadas son comparables a las de otras muestras de referencia de ámbito regional y estatal, lo que avala su representatividad. En conjunto, sus características facilitan el desarrollo de diversas modalidades de investigación, además de diseños genéticamente informativos y la colaboración con distintas iniciativas y consorcios.

Research has emphasized the genetic basis of individual differences in body mass index (BMI); however, genetic factors cannot explain the rapid rise of obesity. Eating behaviors have been stipulated to be the behavioral expression of genetic risk in an obesogenic environment. In this study, we decompose variation and covariation between three key eating behaviors and BMI in a sample of 698 participants, consisting of 167 monozygotic, 150 dizygotic complete same-sex female twins and 64 incomplete pairs from a population-based twin registry in the southeast of Spain, The Murcia Twin Registry. Phenotypes were emotional eating, uncontrolled eating and cognitive restraint, measured by the Three Factor Eating Questionnaire and objectively measured BMI. Variation in eating behaviors was driven by nonshared environmental factors (range: 56%−65%), whereas shared environmental and genetic factors were secondary. All three eating behaviors were correlated with BMI (r = .19–.25). Nonshared environmental factors explained the covariations (Emotional eating–Uncontrolled eating: rE = .54, 95% CI [.43, .64]; BMI–Cognitive restraint: rE = .15, 95% CI [.01, .28]). In contrast to BMI, individual differences in eating behaviors are mostly explained by nonshared environmental factors, which also accounted for the phenotypic correlation between eating behaviors and BMI. Due to the sample size, analyses were underpowered to detect contributions of additive genetic or shared environmental factors to variation and covariation of the phenotypes. Although more research is granted, these results support that eating behaviors could be viable intervention targets to help individuals maintain a healthy weight. The Murcia Twin Registry is being funded by Seneca Foundation — Regional Agency for Science and Technology, Murcia, Spain (grants 03082/PHCS/05, 08633/PHCS/08, 15302/PHCS/10 and 19479/PI/14) and the Spanish Ministry of Science and Innovation (PSI2009–11560 and PSI2014-56680-R). Dr Herle is funded by fellowship from the Medical Research Council UK (MR/T027843/1). A/Prof Colodro-Conde is supported by a QIMR Berghofer fellowship.

The Murcia Twin Registry (MTR) is the only population-based registry in Spain. Created in 2006, the registry has been growing more than a decade to become one of the references for twin research in the Mediterranean region. The MTR database currently comprises 3545 adult participants born between 1940 and 1977. It also holds a recently launched satellite registry of university students (N = 204). Along five waves of data collection, the registry has gathered questionnaire and anthropometric data, as well as biological samples. The MTR keeps its main research focus on health and health-related behaviors from a public health perspective. This includes lifestyle, health promotion, quality of life or environmental conditions. Future short-term development points to the expansion of the biobank and the continuation of the collection of longitudinal data.

Study Objectives There is a well-established association between poor sleep quality and internalizing traits. This relationship has previously been studied using a twin design. However, when it comes to adolescence, there is a paucity of twin studies that have investigated this relationship, despite the importance of this developmental stage for both the development of poor sleep quality and internalizing symptoms. Additionally, anxiety sensitivity, which is commonly associated with poor sleep quality, has not been studied in this context. Our objective was to estimate genetic and environmental influences on the relationships between insomnia, poor sleep quality, and internalizing symptoms in adolescence. Methods Insomnia, poor sleep quality, depression, anxiety, and anxiety sensitivity traits were measured in a sample of 5111 twin pairs from the Twins Early Development Study, born between 1994 and 1996 (mean age 16.32 years [SD = 0.68]). Results A moderate proportion of the variance for the different variables (.29–.42) was explained by genetic factors. Associations between sleep and internalizing variables were moderate (r = .34–.46) and there was a large genetic overlap between these variables (rA= .51–.73). Conclusion This study adds novel information by showing that there are large genetic correlations between sleep disturbances and internalizing symptoms in adolescence.

Twin studies have consistently found that genetic factors explain a substantial proportion of the variance for insomnia. However, studies vary widely in their heritability estimates. Therefore, this meta-analysis aimed to: 1) Estimate the mean heritability of insomnia; 2) Assess heterogeneity among twin studies of insomnia; and 3) Search and analyse characteristics of the studies (moderator variables) that may explain heterogeneity among estimates. For this purpose, separate meta-analyses were carried out for MZ and DZ correlations and for heritability estimates by assuming random-effects models. Thirteen independent samples were included in this meta-analysis. The heterogeneity index for heritability estimates was significant in both best fitting models (I2 = 98.77, P < .0001) and full models (I2 = 97.80, P < .0001). MZ correlations were higher (0.37; 95%CI: 0.31,.43) than DZ correlations (0.15; 95%CI: 0.12,.18). A mean heritability of 0.39 (95%CI: 0.32,.44) was found for insomnia. These results highlight the role of genetic factors in explaining differences among the population on insomnia and Emphasize heterogeneity among studies. Further research is needed to identify variables that could explain this heterogeneity.

Background Although the influence of genetics on chronic low back pain (LBP) has been previously examined, few studies have investigated whether the impact of genetic factors on LBP depends on how the condition is assessed. Methods We investigated the contribution of genetics and environment on chronic LBP: lifetime prevalence, pain intensity (recent and worst) and activity limitation (anytime and recent) in a cross-sectional study with 1,598 adult twins. All twins answered a self-reported questionnaire about health-related questions. We conducted classic twin analyses using structural equation models to estimate the genetic and environmental influences in LBP phenotypes. Results We found a heritability of 26% (95%CI: 0.09-0.42) for lifetime chronic LBP; 36% (95%CI: 0.18-0.52) and 25% (95%CI: 0.03-0.46) for activity limitation due to chronic LBP, related to lifetime and most recent episode, respectively; and heritability of 35% (95%CI: 0.11-0.55) for pain intensity associated with the most recent episode. Genetics showed no significant influence in pain intensity experienced during the worst LBP episode. Conclusions Genetic factors appear to significantly contribute to the variance in chronic LBP including lifetime chronic LBP, activity limitation and pain intensity associated with more recent episodes of LBP, but not for pain intensity associated with people's report of the worst pain episode. Heritability estimates was fairly similar across different LBP outcomes in a population-based twin sample, and not dependent on how it is assessed or experienced. However, we could not detect any significant heritability for a report of intensity experienced during the worst LBP episode experienced. Significance Heritability estimates were similar for different low back pain definitions, and therefore not dependent on how chronic low back pain is experienced or assessed, in the same population-based sample.

Study objectives: Sleep quality is associated with health throughout the life span, which is particularly salient in middle-age and older adulthood. Sleep quality appears to be influenced by both genetic and environmental factors. However, there is still limited information about genetic influences on sleep quality in middle-aged adults, and particularly in those from certain geographical locations. We estimated the magnitude of genetic and environmental influences on sleep quality in a representative sample of middle-aged Spanish twins. Methods: The sample comprised 2150 individuals born between 1939 and 1966, who participate in the Murcia Twin Registry. In order to estimate the heritability of sleep quality variables we performed univariate analyses for the global score on the Pittsburgh sleep quality index and for each of its components. Results: We found moderate but significant heritability (34%) for sleep quality. The genetic variance of the components of the Pittsburgh index ranged from 30% to 45%, except for sleep efficiency for which no genetic influence could be detected. In summary, there was a moderate genetic influence on most dimensions of sleep quality in a sample of adult male and female twins. Shared environment influences were not found. Conclusions: This study adds new information regarding the underlying determinants of sleep quality by providing heritability estimates in a middle-aged population-based representative sample from a geographical location that has not been included in studies of this type previously. This could provide a reference point for future research regarding sleep research in middle-age.

Summary Background & aims While environmental factors are presumed to be primary drivers of food timing, preliminary evidence suggests that genetics may be an additional determinant. The aim was to explore the relative contribution of genetics and environmental factors to variation in the timing of food intake in a Spanish twin population. Because chronotype, bedtime and wake time are related to food timing, covariance with food timing was further assessed. Methods In this observational study, 53 pairs of adult (mean (SD) = 52 (6.03) years) female twins (28 monozygotic; 25 dizygotic) were recruited from the Murcia Twin Register. Zygosity was determined by DNA-testing. Timing of the three main meals of the day was assessed via 7-day dietary records, and the midpoint of food intake was computed by calculating the midpoint between breakfast and dinner times. Chronotype, bedtime and wake time were self-reported. Heritability of food timing and related traits were estimated by comparing monozygotic and dizygotic twin correlations and fitting genetic structural equation models to measured variables. Results We observed genetic influences for food timing, with highest heritability for the midpoint of food intake (64%) in an overweight/obese population (BMI = 26.01 ± 3.77). Genetic factors contributed to a higher degree to the timing of breakfast (56%) than the timing of lunch (38%) or dinner (n.s.). Similarly, heritability estimates were larger in related behavioral traits earlier on in the day (i.e. wake time, (55%)), than those later on in the day (i.e. bedtime, (38%)). Bivariate analyses revealed a significant genetic overlap between food timing and bedtime and chronotype (rG between 0.78 and 0.91). Conclusions Genetic influences appear to account for a significant proportion of the variability in food timing, particularly breakfast. Thus, interventions related to food timing may be more effective when targeting afternoon/evening traits, such as lunch or dinner times. Furthermore, our data suggest shared genetic architecture underlying food timing and phenotypically related traits. Clinical trial NCT03059576 . https://clinicaltrials.gov/ct2/show/NCT03059576 .

The aim of the study was to estimate the extent to which the co-occurrence of poor sleep quality and low back pain is due to the same genetic and/or environmental risk factors or due to a causal association.Cross-sectional data on sleep quality (Pittsburgh Sleep Quality index) and low back pain were collected in a population-based sample of adult twins (N = 2134) registered with the Murcia Twin Registry. Bivariate analysis and structural equation modeling were used.The phenotypic correlation between sleep quality and low back pain was 0.23 (95% confidence interval [CI] = 0.17-0.28). The best-fitting bivariate model included additive genetic and unique environmental factors. Genetic factors accounted for 26% (95% CI = 10-40) and 34% (95% CI = 25-43) of the variability of low back pain and sleep quality, respectively. The correlation between the genetic factors underlying each trait was rG of 0.33 (95% CI = 0.03-0.66), and this overlap of genetic factors explained 42.5% of the phenotypic correlation. On the other hand, nonshared environmental factors of each variable were only fairly correlated rE of 0.19 (95% CI = 0.06-0.31), although this overlap explained 57.5% of the phenotypic correlation. In addition, twins in monozygotic pairs with poorer sleep quality presented more often with low back pain than their co-twins (ρ^ = 0.25, p.0001).The data are compatible with a causal effect of sleep quality on low back pain (or the reverse effect), because the correlations between the genetic and unique environmental factors for each trait were significant and there was a significant correlation between the monozygotic twins' difference scores. Apart from environmental factors that affect both characteristics, there are many individual-specific events that influence low back pain but differ from those influencing sleep quality.

Objective Sleep quality has a significant impact on health and quality of life and is affected, among other factors, by age and sex. However, the prevalence of problems in this area in the general population is not well known. Therefore, our objective was to study the prevalence and main characteristics of sleep quality in an adult population sample. Methods 2,144 subjects aged between 43 and 71 years belonging to the Murcia (Spain) Twin Registry. Sleep quality was measured by self-report through the Pittsburgh Sleep Quality Index (PSQI). Logistic regression models were used to analyse the results. Results The prevalence of poor sleep quality stands at 38.2%. Univariate logistic regression analyses showed that women were almost twice as likely as men (OR: 1.88; 95% confidence interval [95%CI]: 1.54 to 2.28) to have poor quality of sleep. Age was directly and significantly associated with a low quality of sleep (OR: 1.05; 95%CI: 1.03 to 1.06). Conclusions The prevalence of poor sleep quality is high among adults, especially women. There is a direct relationship between age and deterioration in the quality of sleep. This relationship also appears to be more consistent in women.

Summary There is a consistent relationship between body mass index and sleep quality. However, the directionality and possible confounding factors of this relationship are unclear. Our aim is to confirm the association between sleep quality and body mass index, independent of possible genetic confounding, as well as to provide some indirect inferences about the directionality of this association. The co-twin study design was used to analyse the body mass index–sleep relationship in a sample of 2150 twins. We selected two parallel sub-samples of twins discordant for body mass index (n = 430 pairs), or discordant for sleep quality (n = 316 pairs). Sleep quality and body mass index showed an inverse relationship (b = 0.056, P = 0.032) in the global sample. When twins discordant for body mass index were selected, this association maintained a similar effect size and statistical significance, at all levels of the case–control analysis (all discordant pairs b = 0.173, P