IMPORTANCE The long-term association between sleep duration and mental health in children is currently unknown. OBJECTIVE To investigate the prospective associations between sleep duration and symptoms of emotional and behavioral disorders at ages 6, 8, 10, and 12 years. DESIGN, SETTING, AND PARTICIPANTS This population-based cohort study obtained data from the Trondheim Early Secure Study in Trondheim, Norway. A representative, stratified random sample of children born between January 1, 2003, and December 31, 2004, were invited to participate.

Background: The rate of various anxiety disorders in early childhood and whether they continue into middle childhood or adolescence is not known. We therefore report on the prevalence and stability of DSM-5-defined anxiety disorders and their symptoms, capturing the period from preschool to adolescence. Methods: By means of interviewer-based clinical interviews, anxiety was measured in a sample of Norwegian children at six measurement points from age 4 to 14 (n = 1,041). To adjust for time-invariant factors, we applied random intercept cross-lagged panel models (RI-CLPMs) capturing within-person changes. Results: Nearly 10% (95% CI = 7.29, 12.63) had an anxiety disorder at some timepoint. Specific phobia was the most prevalent disorder in early and middle childhood, whereas generalized anxiety disorder (GAD) increased in prevalence and became the most common anxiety disorder at age 14 (4.51%, 95% CI = 2.78, 6.23). When time-invariant confounding was adjusted for, homotypic continuity in anxiety symptoms typically first emerged in late middle childhood or adolescence. Even so, such within-person analyses revealed a heterotypic path from increased number of early childhood symptoms of specific phobia to increased number of GAD symptoms in middle childhood (B = .41, 95% CI = .06, .75). Increased separation anxiety in middle childhood predicted increased symptoms of GAD in adolescence (B = .38, 95% CI = .14, .62), and vice versa (B = .05, 95% CI = .00, .09). Only minor gender differences were revealed. Conclusions: Anxiety disorders are prevalent in childhood. In early childhood, anxiety symptoms generally do not predict later anxiety symptoms. In middle childhood, however, such symptoms are less likely to vanish, indicating this developmental period to be particularly important for preventive and treatment efforts.

Background The term ‘stability’ has different meanings, and its implications for the etiology, prevention, and treatment of depression vary accordingly. Here, we identify five types of stability in childhood depression, many undetermined due to a lack of research or inconsistent findings. Methods Children and parents (n = 1,042) drawn from two birth cohorts in Trondheim, Norway, were followed biennially from ages 4–14 years. Symptoms of major depressive disorder (MDD) and dysthymia were assessed with the Preschool Age Psychiatric Assessment (only parents) and the Child and Adolescent Psychiatric Assessment (age 8 onwards). Results (a) Stability of form: Most symptoms increased in frequency. The symptoms’ importance (according to factor loadings) was stable across childhood but increased from ages 12–14, indicating that MDD became more coherent. (b) Stability at the group level: The number of symptoms of dysthymia increased slightly until age 12, and the number of symptoms of MDD and dysthymia increased sharply between ages 12–14. (c) Stability relative to the group (i.e., ‘rank‐order’) was modest to moderate and increased from ages 12–14. (d) Stability relative to oneself (i.e., intraclass correlations) was stronger than stability relative to the group and increased from age 12–14. (e) Stability of within‐person changes: At all ages, decreases or increases in the number of symptoms forecasted similar changes two years later, but more strongly so between ages 12–14. Conclusions Across childhood, while most symptoms of MDD and dysthymia become more frequent, they are equally important. The transition to adolescence is a particularly vulnerable period: The depression construct becomes more coherent, stability increases, the level of depression increases, and such an increase predicts further escalation. Even so, intervention at any time during childhood may have lasting effects on reducing child and adolescent depression.

Background It is well established that reduced sleep has detrimental effects on school-aged children’s functioning, but the prevalence and stability of objectively measured insufficient sleep throughout childhood is unknown. Methods A sample of 799 children was followed biennially with 24-h 7-day accelerometer (hip-placed) measurements from ages 6 to 12 years. Insufficient sleep was conceptualized as sleeping <7 h on average (AIS) and as the number of nights with <7 h of sleep (NNIS). Results The prevalence of AIS ranged from 1.1% to 13.6%. Of those without AIS, 15.1–64.5% had >1 NNIS. At ages 6–10 years, NNIS was higher on weekend nights, but at age 12 years NNIS was lower on weekends (18.1%) compared to weekdays (23.4%). The stability of AIS was low from ages 6 to 8 years and from 8 to 10 years, but increased from age 10 to 12 years, whereas NNIS evidenced higher stability, increasing sharply through late middle childhood. Conclusions The prevalence of AIS was low during the preschool and early school years but increased toward preadolescence. The 2-year stability of insufficient sleep was very low when conceptualized as AIS and moderate when defined as NNIS, hence NNIS might be more sensitive than AIS. Insufficient sleep appears transient in middle childhood and thus might not warrant intervention unless it fosters impairment and endures.

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