Increased Health Risk in Subjects with High Self-Reported Seasonality

Background: Seasonal variations in mood and behaviour, termed seasonality, are commonly reported in the general population. As a part of a large cross-sectional health survey in Hordaland, Norway, we investigated the relationship between seasonality, objective health measurements and health behaviours. Methodology/Principal Findings: A total of 11,545 subjects between 40–44 years old participated, completing the Global Seasonality Score, measuring seasonality. Waist/hip circumference, BMI and blood pressure were measured, and blood samples were analyzed for total cholesterol, HDL cholesterol, triglycerides and glucose. Subjects also completed a questionnaire on miscellaneous health behaviours (exercise, smoking, alcohol consumption). Hierarchical linear regression analyses were used to investigate associations between seasonality and objective health measurements, while binary logistic regression was used for analysing associations between seasonality and health behaviours. Analyses were adjusted for sociodemographic factors, month of questionnaire completion and sleep duration. Seasonality was positively associated with high waist-hip-ratio, BMI, triglyceride levels, and in men high total cholesterol. Seasonality was negatively associated with HDL cholesterol. In women seasonality was negatively associated with prevalence of exercise and positively associated with daily cigarette smoking. Conclusions/Significance: High seasonality was associated with objective health risk factors and in women also with health behaviours associated with an increased risk for cardiovascular disease

Associations between night work and anxiety, depression, insomnia, sleepiness and fatigue in a sample of Norwegian nurses.

BACKGROUND: Night work has been reported to be associated with various mental disorders and complaints. We investigated relationships between night work and anxiety, depression, insomnia, sleepiness and fatigue among Norwegian nurses. METHODS: The study design was cross-sectional, based on validated self-assessment questionnaires. A total of 5400 nurses were invited to participate in a health survey through the Norwegian Nurses' Organization, whereof 2059 agreed to participate (response rate 38.1%). Nurses completed a questionnaire containing items on demographic variables (gender, age, years of experience as a nurse, marital status and children living at home), work schedule, anxiety/depression (Hospital Anxiety and Depression Scale), insomnia (Bergen Insomnia Scale), sleepiness (Epworth Sleepiness Scale) and fatigue (Fatigue Questionnaire). They were also asked to report number of night shifts in the last 12 months (NNL). First, the parameters were compared between nurses i) never working nights, ii) currently working nights, and iii) previously working nights, using binary logistic regression analyses. Subsequently, a cumulative approach was used investigating associations between NNL with the continuous scores on the same dependent variables in hierarchical multiple regression analyses. RESULTS: Nurses with current night work were more often categorized with insomnia (OR = 1.48, 95% CI = 1.10-1.99) and chronic fatigue (OR = 1.78, 95% CI = 1.02-3.11) than nurses with no night work experience. Previous night work experience was also associated with insomnia (OR = 1.45, 95% CI = 1.04-2.02). NNL was not associated with any parameters in the regression analyses. CONCLUSION: Nurses with current or previous night work reported more insomnia than nurses without any night work experience, and current night work was also associated with chronic fatigue. Anxiety, depression and sleepiness were not associated with night work, and no cumulative effect of night shifts during the last 12 months was found on any parameters

The impact of the Global Seasonality Score on objective health risk factors.

<p>Hierarchic linear regression model controlled for month of questionnaire completion, marital status, income, education, living area and sleep duration (n = 11,544).</p><p>β: Standardized regression coefficient; NS: not significant.</p><p>*p<.05;</p><p>***p<.001.</p

Objective health measurements and health behaviours in different seasonality groups (n = 11,545).

<p>Means are compared by using ANOVA for normally distributed data and Kruskal-Wallis for non-normally distributed data. Standard Deviations are shown in parentheses.</p><p>GSS  =  Global Seasonality Score.</p>a<p>Kruskal-Wallis statistics.</p>b<p>ANOVA statistics.</p>c<p>Post-Hoc analysis (using Least Squares Difference and 0.05 significance level) were reported as follows: 1- Significant difference between the GSS <8 and GSS 8–10 groups, 2- Significant difference between the GSS <8 and GSS ≥11 groups and 3- Significant difference between the GSS 8–10 and GSS ≥11 groups.</p

The impact of High seasonality on health behaviours.

<p>Logistic regression analysis using Global Seasonality Score (GSS) as the predictor variable and objective health risk factors/health behaviours as criterion variables (n = 11,544). The analyses are adjusted for annual income, education, marital status, month of completing the questionnaire, urban/rural residence and sleep duration.</p><p>CI: Confidence Interval.</p><p>*P<0.05.</p><p>**P<0.01.</p

Effect of season on the associations between high seasonality and objective health risk factors.

<p>Analysis of variance using objective health measurements as dependent variables and seasonality group, season and the interaction term seasonality group*season as independent variables. Only significant effects are shown.</p><p><b>GSS = Global Seasonality Score.</b></p

Prevalence of objective health risk factors associated with cardiovascular disease in different seasonality groups.

<p>Each chart has prevalence of health risks on the vertical axis and seasonality group on the horizontal axis, and results for men and women are shown separately. GSS = Global Seasonality Score. Vertical lines depict the 95% Confidence intervals.</p

Demographic characteristics of nurses with different night work status (no night work experience, current night work, previous night work).

<p>The results are reported as mean values with 95% confidence intervals in parentheses.</p><p>HADS = Hospital Anxiety and Depression Scale.</p><p>FQ = Fatigue Questionnaire.</p