Despite much attention on digital media use and young peoples' sleep, the literature on digital media and its impact on sleep in older adolescents and young adults remains to be synthesized. We conducted a systematic review of studies including young people aged 16-25 years. We searched Medline, Web of Science, and CINAHL for observational studies, identifying 60 studies. These studies were assessed for methodological quality. Only studies rated as moderate or high-quality studies were included (n = 42). A narrative synthesis summarized the impact of digital media use on eight sleep outcomes: Bedtime; Sleep onset latency or problems falling asleep; Sleep duration; Early awakening; Sleep disturbance; Daytime tiredness and function; Sleep deficits; Sleep quality. In summary, digital media use was associated to shorter sleep duration and poorer sleep quality. These associations were found for general screen use and use of mobile phone, computer, internet, and social media, but not for television, game console, and tablet use. Most studies investigating bedtime or nighttime use found associations to poor sleep outcomes. Later bedtime and daytime tiredness were associated with mobile phone use at night. Additional research is warranted to draw solid conclusions about the causal direction and to understand the underlying mechanisms.

Background: Sleep is essential for child and adolescent health and well-being. There is an increasing interest in whether electronic media use affects children and young adolescents’ sleep. Prior reviews have focused on a school-aged population. Moreover, it is crucial that research continuously addresses the processes of technology and media use and the implication on sleep. This systematic review examines the evidence of electronic media use related to sleep among 0–15-year-olds. Methods: Searches were carried out in four databases (CINAHL, Web of Science, EMBASE, and Medline). Inclusion criteria included age ≤ 15 years, and intervention, cohort, or cross-sectional studies from western countries. Methodological quality was rated using the Quality Assessment Tool for Quantitative Studies by two independent reviewers. Data was extracted using a standardized data extraction form. Synthesis was done by summarizing results across studies by age groups of 0–5, 6–12, and 13–15 years within four sleep domains: Bedtime and sleep onset; Sleep quality; Sleep duration; Daytime tiredness. Results: The search identified 10,719 unique studies, of which 109 fulfilled inclusion and exclusion criteria and were assessed for methodological quality. In total, 49 studies were included in the review. The study designs were randomized controlled trials (n = 3), quasi-experimental studies (n = 2), prospective cohort studies (n = 15), and cross-sectional studies (n = 29). Evidence for an association between electronic media use and sleep duration was identified, with stronger evidence for 6–15-years-olds than 0–5-year-olds. The evidence for a relationship between electronic media use and other sleep outcomes was more inconclusive. However, for 6–12-year-old children, there was evidence for associations of electronic media use with delayed bedtime and poor sleep quality. For 13–15-year-olds, there was evidence for associations between screen time and problems falling asleep, and between social media use and poor sleep quality. Conclusions: Overall, electronic media use was generally associated with shorter sleep duration in children and adolescents. Studies with stronger research design and of higher quality are needed to draw solid conclusions about electronic media’s impact on other sleep outcomes. Public awareness and interventions could be promoted about the potential negative impact on children’s sleep of electronic media devices that are used excessively and close to bedtime.

Objectives Occupational workload has been associated with an increased risk of osteoarthritis (OA), but only little research has been conducted among female workers. The objective of this study was to analyse if men and women in farming, construction or healthcare work have increased risk of developing OA of the hip or knee. Methods A follow-up study based on register data of the whole Danish working population in the period 1981 to 2006 followed up for hip or knee OA during 1996 to 2006. Cumulative years in occupation were calculated for assessment of dose–response relationship. Gender-specific analyses were carried out with Cox regression models using age as timescale and adjusting for calendar period, income, unemployment and previous knee injury, and done separately for hip and knee OA. Results Male floor layers and bricklayers and male and female healthcare assistants had the highest risks of knee OA, and farmers had the highest risk of hip OA. Male farmers had increased risk of hip OA already after 1–5 years in occupation (HR, 1.63) and a dose–response-related risk of hip OA (HR up to 4.22). Generally, the risk of OA increased with cumulative years in the occupation in both men and women. Conclusions Occupations with heavy physical workload present a strong risk for hip and knee OA in both men and women, and the risks increase with cumulative years in occupation and noticeable hip OA among male farmers.

Background: Mental health represents an important public health issue, and mental health problems have been linked to school dropout. This study aimed to identify mental health groups of high school students using both positive and negative aspects of mental health and to examine whether these mental health groups longitudinally predict school dropout. Methods: We conducted latent class analysis using the Danish National Youth Study 2014 (n = 60,526; mean 17.9 years) to identify clustering of mental health (11 items covering positive and negative aspects of emotional wellbeing and functioning in daily life), separately by sex. The relationship with subsequent school dropout was examined using logistic regression models, adjusted for age, ethnicity and socioeconomic status. Information on dropout status was obtained through educational registers. Results: School dropout rates was highest among first-year students. Four mental health groups were identified: Flourishing (females: 38%, males: 55%), moderate mental health (females: 15%, males: 20%), emotionally challenged (females: 28%, males: 15%) and languishing (females: 19%, males: 10%). Compared to the flourishing group, adjusted odds ratio (AOR) for dropout were 3.43 (95% CI: 2.98, 3.95), 1.73 (95% CI: 1.45, 2.06) and 1.76 (95% CI: 1.52, 2.04) in the languishing, moderate mentally healthy and emotional challenged females. Results in males were comparable. Conclusions: Mental health in high school students cluster together in four categories among both males and females. Students who are languishing, emotionally challenged or moderate mentally healthy have about 1.5-fold to threefold higher risk of dropping out of high school compared with flourishing students. Universal mental health interventions may be a promising strategy, particularly in the first year of high school where most students drop out of school.