Search

PURPOSE:Insufficient and poor sleep patterns are common among adolescents worldwide. Up to now, the evidence on adolescent sleep has been mostly informed by country-specific studies that used different measures and age groups, making direct comparisons difficult. Cross-national data on adolescent sleep that could inform nations and international discussions are lacking. We examined the sleep patterns of adolescents across 24 countries and by gender, age, and affluence groups. METHODS:We obtained sleep data on 165,793 adolescents (mean age 13.5 years; 50.5% girls) in 24 European and North American countries from the recent cross-sectional Health Behaviour in School-aged Children surveys (2013-2014 and 2017-2018). For each country, we calculated the age-standardized mean in sleep duration, timing, and consistency and the proportions meeting sleep recommendations on school and nonschool days from self-reported bedtimes and wake times. We conducted stratified analyses by gender, age, and family affluence group. RESULTS:Adolescent sleep patterns varied cross-nationally. The average sleep duration ranged between 7:47 and 9:07 hours on school days and between 9:31 and 10:22 hours on nonschool days, and the proportion of adolescents meeting sleep recommendations ranged between 32% and 86% on school days and between 79% and 92% on nonschool days. Sleep patterns by gender and affluence groups were largely similar, but older adolescents slept less and went to bed later on school days than younger adolescents in all countries. CONCLUSIONS:The sleep patterns of adolescents vary across countries and sociodemographic groups. Insufficient sleep on school days is common in many countries. Public health and policy efforts to promote healthy adolescent sleep are encouraged.

1. 1. Water vapor sorption studies on a series of ion-exchange resins are presented. The systems investigated include sulfonic acid cation-exchange resins of various degrees of cross-linking, a carboxylic acid resin, and a quaternary ammonium anion-exchange resin. 2. 2. Some direct calorimetric measurements of heats of sorption are presented. Free energies, heats of sorption, and entropies are calculated. 3. 3. The sorption behavior of sulfonic acid resins is compared with that of sulfuric acid. It is concluded that the sulfonic acid groups are osmotically inactive. For the sulfonic acid resins, variations in sorption with ionic state are discussed and interpreted. The partial molal volumes of the hydrated resin systems are studied. 4. 4. The behavior of the cross-linked polystyrene sulfonic acid resins is discussed from the point of view of simple, strong electrolytes in aqueous media. This interpretation is valid for the range 0–75% relative humidity; the influence of cross-linking makes itself felt above this point.