Continuity and Change of Delayed Sleep Phase From Adolescence to Early Adulthood

BACKGROUND AND OBJECTIVES The developmental trajectories and stability of delayed sleep phase (DSP) are poorly known. We investigated how behavioral and psychiatric characteristics, circadian thermoregulation, and the amount and intensity of physical activity (PA) were associated with the continuity of DSP from late adolescence to early adulthood. METHODS We created a population-based longitudinal study in which 1374 adolescents (mean age, 16.8 years; SD, 0.6; 66% girls) self-reported their sleep and psychiatric and behavioral symptoms at timepoint 1 (T1). A DSP-weighted subsample at T2 (7 months from T1; N = 315) and at T3 (19 months from T1; N = 207) provided sleep, PA (GENEActiv actigraphy, 8 days and nights), and skin temperature data (iButton 1922L thermologgers; 3 days and nights) twice. RESULTS Cluster analysis indicated 2 behavioral profiles underlying DSP: 1 pointing to game addiction alone and the other to widely spread behavioral challenges. The stability of DSP was 70%, such that poor self-control, attention-deficit hyperactivity disorder symptoms, and alcohol use together accounted for 18%. Alcohol use and poor self-control accounted for 16% of the emergence of DSP over time. Circadian thermoregulation or the duration or intensity of PA did not associate with the continuity of DSP. CONCLUSIONS DSP is a highly stable condition from late adolescence to early adulthood. Behavioral challenges related to self-control, attention-deficit hyperactivity disorder symptoms, and alcohol use underlie the trajectories of DSP over time. The outcomes emphasize behavioral over the potential physiological components of DSP measured in this study and give clear directions to develop new interventional targets to overcome DSP.