Is social jetlag similar to travel-induced jetlag? Results of a validation study.

Social jetlag (SJL) is defined as the misalignment between the biological clocks and the social clock imposed by work and social constraints. In order to accomplish the workdays duties, people tend to not respect the internally sleep-wake cycle during the week, often using alarm clock to wake-up, which would lead to a chronic form of travel-induced jetlag. This circadian misalignment has been found to be associated with increased health risk and health-impairing behaviors. In this cross-sectional study, we aimed to explore whether the SJL is a valid concept for the travel-induced jetlag symptoms, as well as what is the cutoff point with best parameters for defining the presence of SJL, in a sample of undergraduate students of a university in Southern Brazil. We assessed SJL by the Munich ChronoType Questionnaire (MCTQ) and defined the concept as the difference between the midsleep point on free days and the midsleep point on classes days. The gold standard was defined as having at least one travel-induced jetlag symptom (fatigue, sleepiness or difficulty concentrating). Relative SJL, sensitivity and specificity were calculated for different cutoff points, plotted on ROC curves. A total of 452 students with complete sleep information were included in the analysis. The relative SJL mean was 2 h 23 min (SD = 1 h 24 min; range -3 h to 7 h 58 min) and 63.7% of the students had ≥2 h of relative SJL. All the tested cutoff points of the instrument had low sensitivity and specificity values, covering a small area under the ROC curve (0.487). The best parameters were for the cutoff point ≥2 h, with 63.4% sensitivity and 35.9% specificity. SJL did not revealed to be a valid concept for the studied sample comparing it to travel-induced jetlag symptomatology. One possible explanation for the lack of validity of our results regards the fact that SJL may not have the same apparent wide-term effects as the travel-induced jetlag. Then, the symptoms of SJL do not well represent the symptoms of travel-induced jetlag.

[Analysis on the current situation of insufficient sleep and its association with physical exercise among Chinese Han students aged 9-18 years, in 2014].

Objective: To describe the situation of insufficient sleep and the association between insufficient sleep and physical exercise, among Chinese Han students aged 9-18 years. Methods: We selected 172 197 Chinese Han students aged 9-18 years from the project 2014 Chinese National Survey on Students Constitution and Health. The average sleep duration per day of less than 9 h for children aged 9-12 years and of less than 8 h for adolescents aged 13-18 years, were defined as insufficient sleep. We described the distribution of sleep duration and the prevalence rates of insufficient sleep for each subgroup. Logistic regression models were established to assess the association between insufficient sleep and physical exercise. Results: In 2014, 6.6%, 30.8%, 26.3%, 20.8%, 13.8% and 1.8% of the Chinese Han students self-reported sleep duration were <6, 6-, 7-, 8- and ≥10 h, respectively. The overall prevalence rate of insufficient sleep was 77.2%, with 75.8% for boys and 78.6% for girls. No gender disparity was found at each 9-11 age groups. However, in the 12-18 age groups, the prevalence rates for girls were significantly higher than that for boys. The prevalence rates of insufficient sleep for primary school, middle school and high school students were66.6%, 74.1% and 93.8%, respectively. Rates were increasing with age for children aged 9-12 years and adolescents aged 13-18 years respectively. The three provinces with the lowest prevalence rates of insufficient sleep were Zhejiang (68.8%), Jiangsu (66.7%) and Shaanxi (65.2%). Data from the logistic regression models revealed that, when comparing to those students with only exercise of <0.5 h per day, the exercise hours of 0.5-1 h (OR=0.72, 95%CI: 0.69-0.74) or ≥1 h (OR=0.46, 95%CI: 0.44-0.47) per day seemed as protective factors for insufficient sleep. When compared with physical exercise frequency <2 times per week, the 2 times (OR=0.82, 95%CI: 0.78-0.86) or >2 times (OR=0.65, 95%CI: 0.62-0.68) frequencies also appeared as protective. Conclusions: The prevalence rate of insufficient sleep prevailing among students aged 9-18 years was high, in China. Our data called for setting up effective measures to deal with this situation.

Analysis on the current situation of insufficient sleep and its association with physical exercise among Chinese Han students aged 9-18 years, in 2014 / 中华流行病学杂志

Objective To describe the situation of insufficient sleep and the association between insufficient sleep and physical exercise,among Chinese Han students aged 9-18 years.Methods We selected 172 197 Chinese Han students aged 9-18 years from the project 2014 Chinese National Survey on Students Constitution and Health.The average sleep duration per day of less than 9 h for children aged 9-12 years and of less than 8 h for adolescents aged 13-18 years,were defined as insufficient sleep.We described the distribution of sleep duration and the prevalence rates of insufficient sleep for each subgroup.Logistic regression models were established to assess the association between insufficient sleep and physical exercise.Results In 2014,6.6％,30.8％,26.3％,20.8％,13.8％ and 1.8％ of the Chinese Han students self-reported sleep duration were ＜6,6-,7-,8-and ≥ 10 h,respectively.The overall prevalence rate of insufficient sleep was 77.2％,with 75.8％ for boys and 78.6％ for girls.No gender disparity was found at each 9-11 age groups.However,in the 12-18 age groups,the prevalence rates for girls were significantly higher than that for boys.The prevalence rates of insufficient sleep for primary school,middle school and high school students were 66.6％,74.1％ and 93.8％,respectively.Rates were increasing with age for children aged 9-12 years and adolescents aged 13-18 years respectively.The three provinces with the lowest prevalence rates of insufficient sleep were Zhejiang (68.8％),Jiangsu (66.7％) and Shaanxi (65.2％).Data from the logistic regression models revealed that,when comparing to those students with only exercise of ＜0.5 h per day,the exercise hours of 0.5-1 h (OR=0.72,95％ CI:0.69-0.74) or ≥1 h (OR=0.46,95％ CI:0.44-0.47) per day seemed as protective factors for insufficient sleep.When compared with physicalexercise frequency ＜2 times per week,the 2 times (OR=0.82,95％CI:0.78-0.86) or ＞2 times (OR=0.65,95％CI:0.62-0.68) frequencies also appeared as protective.Conclusions The prevalence rate of insufficient sleep prevailing among students aged 9-18 years was high,in China.Our data called for setting up effective measures to deal with this situation.

Analysis on the current situation of insufficient sleep and its association with physical exercise among Chinese Han students aged 9-18 years, in 2014 / 中华流行病学杂志

Objective To describe the situation of insufficient sleep and the association between insufficient sleep and physical exercise,among Chinese Han students aged 9-18 years.Methods We selected 172 197 Chinese Han students aged 9-18 years from the project 2014 Chinese National Survey on Students Constitution and Health.The average sleep duration per day of less than 9 h for children aged 9-12 years and of less than 8 h for adolescents aged 13-18 years,were defined as insufficient sleep.We described the distribution of sleep duration and the prevalence rates of insufficient sleep for each subgroup.Logistic regression models were established to assess the association between insufficient sleep and physical exercise.Results In 2014,6.6％,30.8％,26.3％,20.8％,13.8％ and 1.8％ of the Chinese Han students self-reported sleep duration were ＜6,6-,7-,8-and ≥ 10 h,respectively.The overall prevalence rate of insufficient sleep was 77.2％,with 75.8％ for boys and 78.6％ for girls.No gender disparity was found at each 9-11 age groups.However,in the 12-18 age groups,the prevalence rates for girls were significantly higher than that for boys.The prevalence rates of insufficient sleep for primary school,middle school and high school students were 66.6％,74.1％ and 93.8％,respectively.Rates were increasing with age for children aged 9-12 years and adolescents aged 13-18 years respectively.The three provinces with the lowest prevalence rates of insufficient sleep were Zhejiang (68.8％),Jiangsu (66.7％) and Shaanxi (65.2％).Data from the logistic regression models revealed that,when comparing to those students with only exercise of ＜0.5 h per day,the exercise hours of 0.5-1 h (OR=0.72,95％ CI:0.69-0.74) or ≥1 h (OR=0.46,95％ CI:0.44-0.47) per day seemed as protective factors for insufficient sleep.When compared with physicalexercise frequency ＜2 times per week,the 2 times (OR=0.82,95％CI:0.78-0.86) or ＞2 times (OR=0.65,95％CI:0.62-0.68) frequencies also appeared as protective.Conclusions The prevalence rate of insufficient sleep prevailing among students aged 9-18 years was high,in China.Our data called for setting up effective measures to deal with this situation.