Adolescents’ trajectories of depression and anxiety symptoms prior to and during the COVID-19 pandemic and their association with healthy sleep patterns

www.nature.com/scientificreports OPEN Adolescents’ trajectories of depression and anxiety symptoms prior to and during the COVID‑19 pandemic and their association with healthy sleep patterns Serena Bauducco 1,2*, Lauren A. Gardner 3, Scarlett Smout 3, Katrina E. Champion 3, Cath Chapman 3, Amanda Gamble 4, Maree Teesson 3, Michael Gradisar 5,6 & Nicola C. Newton 3 The COVID-19 pandemic has seen a rise in anxiety and depression among adolescents. This study aimed to investigate the longitudinal associations between sleep and mental health among a large sample of Australian adolescents and examine whether healthy sleep patterns were protective of mental health in the context of the COVID-19 pandemic. We used three waves of longitudinal control group data from the Health4Life cluster-randomized trial (N = 2781, baseline Mage = 12.6, SD = 0.51; 47% boys and 1.4% ‘prefer not to say’). Latent class growth analyses across the 2 years period identified four trajectories of depressive symptoms: low-stable (64.3%), average-increasing (19.2%), high-decreasing (7.1%), moderate-increasing (9.4%), and three anxiety symptom trajectories: lowstable (74.8%), average-increasing (11.6%), high-decreasing (13.6%). We compared the trajectories on sociodemographic and sleep characteristics. Adolescents in low-risk trajectories were more likely to be boys and to report shorter sleep latency and wake after sleep onset, longer sleep duration, less sleepiness, and earlier chronotype. Where mental health improved or worsened, sleep patterns changed in the same direction. The subgroups analyses uncovered two important findings: (1) the majority of adolescents in the sample maintained good mental health and sleep habits (low-stable trajectories), (2) adolescents with worsening mental health also reported worsening sleep patterns and vice versa in the improving mental health trajectories. These distinct patterns of sleep and mental health would not be seen using mean-centred statistical approaches. Mental disorders are the leading cause of disability among young people aged up to 24 years worldwide, accounting for one quarter of all years lived with disability1. In Australia, mental disorders make up three of the five leading causes of burden of disease among those aged 12–24 years2 and cost the economy approximately $200–220 billion yearly3. The COVID-19 pandemic has caused disruptions to all facets of adolescent development and exacerbated mental health issues such as depression, anxiety and self h arm4–7. Examining modifiable factors that were protective of mental health throughout this global crisis can offer insights on targets for prevention and early intervention, especially since improving the mental health of young people is a critical public health priority8. There is growing evidence that sleep is a key modifiable factor associated with mental h ealth9–14. Human sleep is primarily under biological control, governed by the well-supported two-process model of s leep15,16. The first process is sleep homeostatis, whereby pressure to sleep builds across the waking day and evening and dissipates 1 Flinders University, Adelaide, Australia. 2Center for Health and Medical Psychology, Örebro University, Fakultetsgatan 1, 701 82 Örebro, Sweden. 3The Matilda Centre for Research in Mental Health and Substance Use, The University of Sydney, Sydney, Australia. 4The Woolcock Institute, Macquarie University, Sydney, Australia. 5WINK Sleep Pty Ltd, Adelaide, Australia. 6Sleep Cycle AB, Gothenburg, Sweden. *email: Scientific Reports | (2024) 14:10764 | https://doi.org/10.1038/s41598-024-60974-y 1 Vol.:(0123456789) www.nature.com/scientificreports/ during sleep. As adolescents develop, their ability to build sleep pressure in the evening declines, resulting in increased alertness in the evening. This inevitably results in a delay in the onset of sleep (i.e., a longer sleep onset latency)16. The second process—the circadian rhythm—is a cycle of sleep and wake across the 24 h day, and is of particular relevance during adolescence. From about age 10 to 20 years, the timing of the circadian rhythm delays, resulting in a later onset of sleep in the evening, and a later rise time (when allowed to sleep-in)16. However, 5 out of 7 days of the week, adolescents are prevented from sleeping at their natural circadian times as they need to wake relatively early to prepare for, travel to, and attend school17. This inevitably results in a restriction of sleep across the school week (i.e., shortened total sleep time) and weekend catch-up, which leads to irregular sleep and pepetuates weekday sleep debt17. Multiple studies have shown that poor sleep during paediatric development can increase the odds of developing anxiety and depression, with two mechanisms implicated9. First, the restriction of sleep (less total sleep time) has been shown to dampen positive mood and hinder one’s next-day emotion regulation9. Second, an extended sleep onset latency is proposed to create an ideal environment for repetitive negative thinking (i.e., worry and rumination), which has been linked to both depression and anxiety in young people. An extended sleep onset latency is common among later chronotypes, which may be a predisposing factor for the development of depression and anxiety symptoms18. Conversely, a healthy sleep profile (particularly short sleep onset latency—between 5 and 30 min19, sufficient total sleep time—between 8 and 10 h20, and less daytime sleepiness) is associated with increased mental resilience (i.e., lower symptoms of anxiety and depression)21,22. Therefore, sleep is an important risk-/protective factor for the development of mental ill-health. During the COVID-19 pandemic, mental resilience was tested on a global scale, and many adolescents experienced heightened p sychopathology4–7. Sleep was also impacted, potentially relating to heightened stress and restrictions on movement and closure of schools; however, evidence as to whether healthy sleep improved or worsened has been m ixed23–25. Surprisingly, one longitudinal study found that the prevalence of depressive symptoms, anxiety symptoms and sleep problems was higher before, compared to during and after, the pandemic26. While studies focusing on average changes are informative, they might miss for whom changes occur. Did all adolescents experience worse sleep and mental health? Were adolescents with healthy sleep patterns more resilient? For example, later c hronotype26,27, shorter sleep d uration27 and insomnia s ymptoms28 were associated with higher risk for adolescents’ mental ill-health during the pandemic. Identifying subgroups of adolescents at lower risk for mental ill-health during the pandemic, and thoroughly examining protective sleep characteristics, can inform key targets for prevention and early interventions in this population. Previous studies, however, have examined changes across their entire samples, and have examined only a few i (...truncated)