Children with obesity have poorer circadian health as assessed by a global circadian health score.

BACKGROUND: Circadian health refers to individuals' well-being and balance in terms of their circadian rhythm. It is influenced by external cues. In adults, a close relationship between circadian-related alterations and obesity has been described. However, studies in children are scarce, and circadian health and its association with obesity have not been evaluated globally. We aimed to assess whether circadian health differed between children with and without obesity as determined by a global circadian score (GCS) in a school-age population. METHODS: Four hundred and thirty-two children (7-12 years) were recruited in Spain. Non-invasive tools were used to calculate the GCS: (1) 7-day rhythm of wrist temperature (T), activity (A), position (P), an integrative variable that combines T, A, and P (TAP); (2) cortisol; and (3) 7-day food and sleep records. Body mass index, body fat percentage, waist circumference (WC), melatonin concentration, and cardiometabolic marker levels were determined. RESULTS: Circadian health, as assessed by the GCS, differed among children with obesity, overweight, and normal weight, with poorer circadian health among children with obesity. Children with obesity and abdominal obesity had 3.54 and 2.39 greater odds of having poor circadian health, respectively, than did those with normal weight or low WC. The percentage of rhythmicity, a marker of the robustness of the TAP rhythm, and the amplitude, both components of the GCS, decreased with increasing obesity. Different lifestyle behaviors were involved in the association between circadian health and obesity, particularly protein intake (P = 0.024), physical activity level (P = 0.076) and chronotype (P = 0.029). CONCLUSIONS: The GCS can capture the relationship between circadian health and obesity in school-age children. Protein intake, physical activity level, and chronotype were involved in this association. Early intervention based on improving circadian health may help to prevent childhood obesity.

Blunted rest-activity rhythms link to higher body mass index and inflammatory markers in children.

STUDY OBJECTIVES: Disturbances of rest-activity rhythms are associated with higher body mass index (BMI) in adults. Whether such relationship exists in children is unclear. We aimed to examine cross-sectional associations of rest-activity rhythm characteristics with BMI z-score and obesity-related inflammatory markers in school-age children. METHODS: Participants included 411 healthy children (mean ± SD age 10.1 ± 1.3 years, 50.8% girls) from a Mediterranean area of Spain who wore wrist accelerometers for 7 consecutive days. Metrics of rest-activity rhythm were derived using both parametric and nonparametric approaches. Obesity-related inflammatory markers were measured in saliva (n = 121). RESULTS: In a multivariable-adjusted model, higher BMI z-score is associated with less robust 24-h rest-activity rhythms as represented by lower relative amplitude (-0.16 [95% CI -0.29, -0.02] per SD, p = 0.02). The association between BMI z-score and relative amplitude persisted with additional adjustment for sleep duration, and attenuated after adjustment for daytime activity level. Less robust rest-activity rhythms were related to increased levels of several salivary pro-inflammatory markers, including C-reactive protein, which is inversely associated with relative amplitude (-32.6% [-47.8%, -12.9%] per SD), independently of BMI z-score, sleep duration, and daytime activity level. CONCLUSION: Blunted rest-activity rhythms are associated with higher BMI z-score and salivary pro-inflammatory markers already at an early age. The association with BMI z-score seem to be independent of sleep duration, and those with pro-inflammatory markers further independent of BMI z-score and daytime activity. Novel intervention targets at an early age based on improving the strength of rest-activity rhythms may help to prevent childhood obesity and related inflammation. CLINICAL TRIALS REGISTRATION: NCT02895282.

Late Eating Is Associated with Obesity, Inflammatory Markers and Circadian-Related Disturbances in School-Aged Children.

Late eating has been shown to promote metabolic dysregulation and to be associated with obesity in adults. However, few studies have explored this association in children. We compared the presence of obesity, metabolic alterations and circadian-related disturbances between school-aged children who were early dinner eaters (EDE) or late dinner eaters (LDE). School-age children (n = 397; 8-12 years; mean BMI (range): 19.4 kg/m2 (11.6-35.1); 30.5% overweight/obesity) from Spain were classified into EDE and LDE, according to dinner timing (Median: 21:07). Seven-day-dietary-records were used to assess food-timing and composition. Non-invasive tools were used to collect metabolic biomarkers (saliva), sleep and circadian-related variables (body-temperature and actigraphy). Compared to EDE, LDE were more likely to be overweight/obese [OR: 2.1 (CI: 1.33, 3.31); p = 0.002], and had higher waist-circumference and inflammatory markers, such as IL-6 (1.6-fold) (p = 0.036)) and CRP (1.4-fold) than EDE (p = 0.009). LDE had alterations in the daily patterns of: (a) body-temperature, with a phase delay of 26 min (p = 0.002), and a reduced amplitude (LDE = 0.028 (0.001) and EDE = 0.030 (0.001) (Mean (SEM); p = 0.039); (b) cortisol, with a reduced amplitude (LDE = 0.94 (0.02) and EDE = 1.00 (0.02); p = 0.035). This study represents a significant step towards the understanding of novel aspects in the timing of food intake in children.

Evening types have social jet lag and metabolic alterations in school-age children.

Chronotype has been mostly assessed with subjective scales. Objective assessment has been undertaken with actigraphy, although problems may occur in classifying chronotype. The aims of the study were to assess chronotype in school-age children using a novel integrative measurement (TAP) derived from non-invasive assessments of wrist temperature (T) physical activity (A) and body position (P) and to explore associations between chronotype, sleep disturbances, and metabolic components. Four-hundred-thirty-two children of 8-12 years were recruited from a Mediterranean area of Spain. Measurements were: (a) Chronotype objectively (7-day-rhythms of TAP) and subjectively measured (Munich-chronotype-self-reported questionnaire); (b) sleep rhythms and light exposition; (c) 7-day-diaries of food intake; (d) anthropometry and metabolic parameters; (e) academic scores. TAP acrophase was able to assess eveningness. As compared to more morning-types, more evening-types displayed lower amplitude in temperature rhythms, increased physical activity in the evening, delayed sleep and midpoint of intake and had more frequent social jet lag (P < 0.05). More evening-types had higher light intensity at 2 h before sleep and lower melatonin values (01:00 h). Eveningness associated with higher BMI and metabolic risk (higher values of insulin, glucose, triglycerides and cholesterol). Evening-types presented better grades in art. In conclusion, more evening-types, as objectively assessed, presented sleep alterations, social jet lag, obesity and higher metabolic risk.

Saliva as a non-invasive tool for assessment of metabolic and inflammatory biomarkers in children.

BACKGROUND & AIMS: Epidemiological studies in school-age children are challenging, particularly those that aim to analyse metabolic markers on blood samples obtained via invasive and stressful procedures. The objective of this paper is to evaluate the use of saliva, as a non-invasive tool in epidemiological studies performed in school-age children, to capture metabolic changes associated with body mass index (BMI), dietary characteristics and physical activity in both boys and girls. METHODS: This is an observational study in which healthy children of ages between 8 and 12 years (n = 129, 60 girls and 69 boys) from three schools in a Mediterranean area of Spain were included. A panel of biomarkers was measured in serum and saliva and correlated with BMI, dietary characteristics and physical activity. RESULTS: Significant positive correlation between serum and salivary levels were detected for CRP (r = 0.770) in all included children, and boys (r = 0.805) and girls (r = 0.775) separately (P < 0.001, in all cases) and for insulin in girls (r = 0.442; P < 0.05). Among all studied salivary biomarkers, insulin was significantly correlated with the three factors studied: positively with BMI and negatively with dietary characteristics (intake and composition) and physical activity (P < 0.05). Obesity and diet composition were both positively associated to pro-inflammatory biomarkers, CRP and IL1b; while diet composition shared with physical activity levels the correlation with IL6 (positive with energy, fat, carbohydrate and saturated fatty acid intake, and negative with cholesterol intake and average physical activity in boys), NGF and glucose (in both cases correlations were negative with diet composition and physical activity variables) (P < 0.05, in all cases). Sex differences were detected in serum glucose and TNFα. CONCLUSIONS: Biomarkers in saliva are able to capture differences in BMI, dietary characteristics and physical activity levels in school-age children. Saliva may potentially constitute a useful non-invasive and stress-free tool to evaluate metabolic markers of inflammation and/or metabolism related to BMI and lifestyle in a sex-dependent manner.

Circadian health differs between boys and girls as assessed by non-invasive tools in school-aged children.

BACKGROUND & AIMS: Assessment of circadian health is confined to adults. However, understanding circadian status of school-aged children is necessary due to its health implications. The aim was to develop 1) a protocol to assess circadian function in school-aged children by combining the best non-invasive tools previously validated in adults; 2) a score to capture circadian function in children including food timing. This protocol will allow to explore gender differences and to compare the circadian function of school-aged children with adults from the same Mediterranean area. METHODS: Healthy children (8-12 y) from 3 schools in a Mediterranean area of Spain were recruited (n = 248; 125 males and 123 females). Several non-invasive tools were used: a) 7-day-diaries of food timing and food intake, physical-activity and sleep, b) Munich-chronotype-self-reported-questionnaire; c) cortisol and melatonin saliva determinations; d) 7-day-rhythms of wrist temperature (T), activity (A), position (P) and the integrative variable TAP e) 7-day-light exposure. RESULTS: We have constructed the first school-aged children population for the assessment of circadian function (ONTIME-Jr) and a new circadian score has been developed. Among circadian-related measures, TAP was the most suitable and reliable to determine circadian system characteristics. Circadian function was better in girls than in boys [circadian score (AU) Mean ± SD (girls, 1216 ± 153 vs. 1159 ± 173 boys, P = 0.012)], and also in school-aged children than in adults from the same Mediterranean area (Circadian-Function-Index: children 0.47 ± 0.06 vs. adults 0.45 ± 0.06 P = 0.001). CONCLUSIONS: A new protocol, including TAP and food timing, demonstrated to be reliable in assessing circadian function in children. These non-invasive techniques provide the wherewithal for paediatricians to assess circadian function in clinical practice. TRIAL REGISTRATION: Chronobiology and childhood obesity (ONTIME-Jr: Obesity, Nutrigenetics, Timing and Mediterranean, Junior). ClinicalTrials.gov ID: NCT02895282, October 2014.