Associating night-shift work with lifetime use of sleep medication and sleep quality in a cohort of female nurses.

Night-shift workers often sleep at moments, not in sync with their circadian rhythm. Though the acute effects of night-shift work on sleep quality directly after a night shift are well described, less is known about the chronic effects of night-shift work on sleep. We associated ever-working night shifts and recently working night shifts (<4 wk) with lifetime use of sleep medication and melatonin, self-reported average sleep duration and sleep quality over the 4 wk preceding inclusion (measured using the Medical Outcomes Study Sleep scale). We explored trends in sleep outcomes with average frequency of night shifts per week, tenure of night-shift works in years, and time since last performed night work. This research was conducted within the Nightingale study which is a Dutch cohort study of 59,947 female registered nurses aged 18 to 65. Working night shifts was not associated with self-reported nonoptimal sleep length and sleep quality. However, we observed higher odds of lifetime use of sleep medication for nurses who ever-worked night shifts (OR 1.24; 95% CI 1.13, 1.35) and who recently worked night shifts (OR 1.13; 95% CI 1.05, 1.22); with night-shift work frequency and tenure being associated with lifetime use of sleep medication (P-value for trend < 0.001 for both). Odds for melatonin use were elevated for nurses who ever worked night shifts (OR 1.55; 95% CI 1.40, 1.71) and recently worked night shifts (OR 1.72; 95% CI 1.59, 1,86). The findings of this study have practical implications for healthcare organizations that employ nurses working night shifts. The observed associations between night-shift work and increased lifetime use of prescribed sleep medication and melatonin highlight the need for targeted support and interventions to address the potential long-term sleep problems faced by these nurses.

Single-item chronotype is associated with dim light melatonin onset in lymphoma survivors with fatigue.

Chronotype is frequently assessed in human observational studies using various morningness-eveningness questionnaires. An alternative single-item chronotype question has been proposed for its reduced administration time and its accessibility to all types of populations. We investigated whether this single-item chronotype is associated with dim light melatonin onset, the "gold standard" for estimating the endogenous circadian phase. We used data from a randomised trial in 166 (non-)Hodgkin lymphoma survivors with cancer-related fatigue. All participants completed a questionnaire, including a single-item chronotype question. A subsample of 47 participants also provided saliva samples before sleep onset for melatonin measurement. Using multiple linear regression, we examined whether chronotype based on a single question was associated with dim light melatonin onset. The subsample of 47 participants had a mean age of 44.6 years. The mean (SD) dim light melatonin onset was at 8:42 (1:19) p.m. and the most common chronotype was more evening than morning person (29.2%). A gradual increase in dim light melatonin onset with later chronotype (i.e. evening preference) was observed, with a mean ranging from 7:45 p.m. in definite morning persons to 9:16 p.m. in definite evening persons. Our study shows that single-item chronotype is associated with dim light melatonin onset as a marker of the endogenous circadian phase of fatigued lymphoma survivors. This type of chronotype assessment can therefore be a useful alternative for more extensive morningness-eveningness questionnaires.

Pubertal Timing and Cardiometabolic Markers at Age 16 Years.

OBJECTIVE: To examine the association between pubertal timing and cardiometabolic markers among adolescents. STUDY DESIGN: We used data from Dutch adolescents participating in a birth cohort study. The study population for the current study consisted of 799 adolescents of whom data were available for at least 1 of the exposure variables (pubertal timing and/or age at menarche) and any of the cardiometabolic markers (waist circumference, cholesterol, blood pressure [BP], glycated hemoglobin) measured at age 16 years. Adolescents self-reported pubertal development at ages 11, 14, and 16 years. We categorized participants with early (84 girls, 88 boys), intermediate (240 girls, 211 boys), or late pubertal timing (89 girls, 85 boys). We estimated differences in cardiometabolic markers using linear regression analysis. RESULTS: Girls with early pubertal timing had 1.54 cm larger waist circumference (95% CI .05; 3.03) and 3.98 mm Hg higher systolic BP (95% CI 1.69; 6.27) at age 16 years than girls with intermediate pubertal timing. The association with systolic BP remained after adjusting for childhood body mass index (BMI) (age 8 years) but attenuated after adjusting for BMI in adolescence (age 16 years). Boys with early pubertal timing had 0.79 mmol/mol lower glycated hemoglobin (95%CI -1.38; -0.20) than boys with intermediate pubertal timing. CONCLUSIONS: Girls with early pubertal timing had unfavorable BP levels at age 16 years, independent of BMI in childhood. Girls and boys with late pubertal timing had a tendency for lower waist circumference, but no differences in other cardiometabolic markers. Late pubertal timing does not appear to be a risk factor for unfavorable cardiometabolic markers in adolescence.

Musculoskeletal complaints while growing up from age 11 to age 14: the PIAMA birth cohort study.

For musculoskeletal complaints (MSCs) among adults, several risk factors are known, but the most important determinant is an earlier episode of MSCs. Research has shifted to younger ages, showing a high prevalence of MSCs among children and adolescents. Our purpose was to evaluate the prevalence of MSCs among those growing up from age 11 to 14 and to explore the role of several sociodemographic, growth and development, psychosocial, and lifestyle factors. Data collected at age 11 (n = 2651) and age 14 (n = 2522) in the ongoing Dutch Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study were used. Analyses included multiple logistic regression analyses using stepwise backward selection. The 1-year prevalence of any MSCs for at least 1 month increased from 15.8% at age 11 to 24.4% at age 14, and this was also found for upper extremity complaints (from 4.7% to 7.6%), back complaints (from 2.7% to 9.3%), and lower extremity complaints (from 11.9% to 14.7%). More MSCs were found among girls, those with sports injuries, those with sleeping problems, and those with daytime tiredness, although complaints at age 11 were by far the most important factor associated with MSCs at age 14 for all pain sites. This study showed that MSC is already common at an early age and that already at age 14 the factor with the strongest association is an earlier episode of MSCs. Sleeping problems and tiredness may also play a role in the early development of MSCs, either as determinant or as a consequence.

Family history of myocardial infarction, stroke and diabetes and cardiometabolic markers in children.

AIMS/HYPOTHESIS: Despite the overlap in occurrence of cardiovascular disease (CVD) and type 2 diabetes and their risk factors, family history of these diseases has not yet been investigated simultaneously in relation to cardiometabolic markers in offspring. We examined how a family history of CVD and/or diabetes relates to cardiometabolic markers in offspring, and to what extent these diseases independently contribute to cardiometabolic markers. METHODS: We used data from 1,374 12-year-old children and their parents participating in a birth cohort study in the Netherlands. Family history of CVD (myocardial infarction [MI] and stroke) and diabetes were reported by the parents. Children were classified as 'no', 'moderate' or 'strong' family history, based on early/late onset of disease in parents and grandparents. Cardiometabolic markers were measured at 12 years of age: waist circumference, cholesterol, blood pressure and HbA1c. RESULTS: Compared with those with no family history, children with a strong family history of MI and/or stroke and/or diabetes (29% of the study population) had 0.13 mmol/l higher total cholesterol (TC) (95% CI 0.03, 0.23) and 0.18 higher TC/HDL-cholesterol (HDLC) ratio (95% CI 0.04, 0.32). A strong family history of MI or diabetes was independently associated with unfavourable cardiometabolic markers specific to those diseases. These associations remained after adjusting for BMI. Children with a moderate family history had no unfavourable cardiometabolic markers. CONCLUSIONS/INTERPRETATION: One-third of the children had a strong family history of CVD and/or diabetes. These children had higher TC levels and TC/HDLC ratios than children with no family history. A strong family history of MI or diabetes was independently associated with unfavourable cardiometabolic markers specific to those diseases.

Time in bed, sleep quality and associations with cardiometabolic markers in children: the Prevention and Incidence of Asthma and Mite Allergy birth cohort study.

We investigated associations of time in bed and multiple sleep quality characteristics with cardiometabolic markers in children. Data from the prevention and incidence of asthma and mite allergy study, a population-based prospective birth-cohort study started in 1996-1997 in the Netherlands, were analysed. In total 1481 children aged 11-12 years completed a questionnaire (including questions on sleep) and underwent a medical examination. We measured body mass index, waist circumference, total- and high-density lipoprotein cholesterol, blood pressure and glycated haemoglobin. Results showed that in girls, some sleep characteristics were related to anthropometrics (body mass index, waist circumference) and cholesterol. Girls who had a long time in bed (11-12.5 h) had 0.16 lower body mass index z-score (95% confidence interval -0.31; -0.01) and 0.99 cm smaller waist circumference (95% confidence interval -2.01; -0.13) compared with girls who spent 10-10.5 h in bed. Girls who went to bed late and rose early had 0.16 mm higher total cholesterol (95% confidence interval 0.01; 0.31) and 0.08 mm higher high-density lipoprotein cholesterol (95% confidence interval 0.01; 0.14) than 'early to bed/early rise' girls. Girls with night-time awakenings had 0.14 mm higher total cholesterol (95% confidence interval 0.03; 0.25) than girls without night-time awakenings. Girls who felt sleepy/tired ≥1 day per week had 0.10 mm lower high-density lipoprotein cholesterol (95% confidence interval -0.16; -0.04) and 0.17 mm higher total cholesterol/high-density lipoprotein cholesterol ratio (95% confidence interval 0.02; 0.32) than girls who did not feel sleepy. No associations were found for boys. Sleep characteristics were not related to blood pressure and glycated haemoglobin, and effect sizes of the associations in girls were small. Therefore, we consider it premature to propose that improved sleep could reduce cardiovascular risk during childhood.

Adherence to the WHO's healthy diet indicator and overall cancer risk in the EPIC-NL cohort.

BACKGROUND: A healthy dietary pattern defined by international recommendations of the World Health Organisation (WHO) has been shown to reduce overall mortality risk. It is unknown whether this healthy dietary pattern is associated with overall cancer incidence. DESIGN: In total 35,355 men and women within the Dutch European Prospective Investigation into Cancer and Nutrition-cohort were followed for cancer occurrence. Diet was assessed through a validated food-frequency questionnaire. We computed a dietary score for all participants based on the seven WHO dietary guidelines for the prevention of chronic diseases (Healthy Diet Indicator (HDI)). We used the existing HDI score based on the 1990 WHO guidelines, and adapted it to meet with the 2002 WHO guidelines. Multivariate-adjusted Cox proportional hazards analysis was used to examine the association between adherence to the HDI and subsequent overall cancer risk. RESULTS: A number of 3,007 new cancers were identified during a mean follow-up of 12.7 years. Adherence to the HDI was not associated with a reduced overall cancer risk. The hazard ratio (HR) of overall cancer associated with a one-point increment of the HDI was 0.96 (95% CI 0.89-1.03) in men, and 1.00 (95% CI 0.96-1.04) in women. Adherence to the HDI was not associated with smoking-related cancer ((HR men: 0.94 (95% CI 0.84-1.04); HR women: 1.00 (95% CI 0.94-1.07)), or alcohol-related cancer ((HR men: 1.02 (95% CI 0.87-1.20); HR women: 1.03 (95% CI 0.98-1.08)). CONCLUSIONS: Greater adherence to the WHO's Healthy Diet Indicator, a dietary pattern for prevention of chronic diseases, was not associated with reduced overall, smoking-related or alcohol-related cancer risk in men or women.

Plasma-serum cholesterol differences in children and use of measurements from different specimens.

BACKGROUND: We aimed to assess absolute plasma-serum differences and differences in ranking of total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), and TC/HDLC ratio in children. METHODS: We analysed data of 412 children participating in a Dutch birth cohort. TC, HDLC, and TC/HDLC ratio were determined in plasma at age 8 and 12 years and in serum at age 12 years. RESULTS: Compared to serum, plasma TC at age 12 years was 0.07 mmol/l lower (95% CI -0.08 to -0.06), plasma HDLC was 0.06 mmol/l higher (95% CI 0.05-0.07), and plasma TC/HDLC ratio was 0.19 lower (95% CI -0.20 to -0.17) (p < 0.0001). Intraclass correlation coefficients (ICCs) for ranking of TC, HDLC, and TC/HDLC ratio at age 12 years were 0.970, 0.745, and 0.979, respectively. ICCs for ranking of 8- to 12-year change of TC, HDLC, and TC/HDLC ratio were 0.971, 0.957, and 0.955, respectively. CONCLUSIONS: Cholesterol was systematically different in plasma and serum, and use of plasma would result in a more favourable lipid profile of children (lower TC, higher HDLC, and lower TC/HDLC ratio). Nevertheless, consistency in ranking of children according to plasma or serum cholesterol concentrations was very high. Age-related change in cholesterol can be validly assessed by ranking the difference between serum concentrations at one age and plasma concentrations at another age.