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Associations between sleep duration, insomnia, depression, anxiety and registry-based school grades: A longitudinal study among high-school students

Picture of Linn Nyjordet Evanger

Linn Nyjordet Evanger

I am a PhD candidate at the University of Bergen, Norway. My PhD focuses on associations between adolescents’ sleep patterns, mental health, school performance, and school start times. More on Research Gate.

Sleep Duration, Insomnia, Mental Health and School Grades

Written Interview

What was your motivation for doing this study? 

We know that inadequate sleep duration on school nights is common in adolescent cohorts globally, assumably due to a biologically based delay in their circadian timing which interacts with various psychological, social, and environmental changes. Adolescence also often marks the debut of clinical sleep disorders, including insomnia. Several previous studies have shown that adolescents with shorter sleep duration and insomnia often have poorer school grades, but few have explored these associations longitudinally. The motivation behind this study was to enhance the understanding of how inadequate sleep patterns may affect adolescents’ learning potentials and -outcomes over time, by using a longitudinal study design.  

What were the aims of your study?  

The primary aim was to investigate whether sleep duration and insomnia at baseline were associated with objective school performance over time among older adolescents. We also wanted to explore whether these potential associations remained when controlling for the adolescents’ depression- and anxiety levels.  

Who did you recruit for this study and how did you collect the data? 

All first-year high school students in two counties in Western Norway were initially invited to the study by their school staff in 2019. Self-reported data on sleep patterns and mental health were collected through a web-based survey. Responders of the 2019 survey were re-invited in 2021. The students were asked about their typical sleep habits on weekdays, including when they usually went to bed, nocturnal awakenings, and wake-up times. The survey also asked about symptoms of insomnia, depression, and anxiety. Grade point averages (GPAs) for each school year were collected through the county administrations for students consenting to this. We chose to only include students born in 2002 to eliminate any potential age-related effects. In total, 1092 students were included in our final longitudinal sample.  

What were your main findings? 

Shorter sleep duration and insomnia in the first year of high school were both associated with poorer GPA in the third year of high school when we controlled for the students’ initial GPAs. These associations remained significant when we controlled for symptoms of depression, anxiety, and sex.  

Did you have any surprising or unexpected findings? 

I was surprised that when the associations between sleep duration, insomnia, and GPA were controlled for levels of anxiety and depression, neither anxiety nor depression at baseline were significant predictors of GPA over time. Otherwise, the results were mostly expected. 

What were the biggest challenges doing this study? 

It is always challenging working with large datasets. The biggest challenge was perhaps determining which students to be included or not, as the large sample size also meant high diversity. For example, some studied part-time, and the number of courses each student had taken varied. Furthermore, we know that characteristics related to students’ school- and class environment may affect school grades and wanted to take this into consideration. The data were therefore analysed using linear mixed models.   

What are the implications for what you have found? 

The longitudinal design suggests that students with shorter sleep duration and insomnia have poorer academic outcomes over time. However, as the study was observational, we cannot draw causal conclusions, as the associations may have been affected by factors other than the ones investigated.  

What do you think are the next studies that are needed?  

I would say more studies on the associations between sleep patterns, school performance, and school start times.  

Recent publications from ESRS members

  1. Constantino et al (2025)The bright and dark side of blue-enriched light on sleep and activity in older adults. Geroscience
  2. Reis et al (2025)Sleep and circadian rhythms in delayed sleep-wake phase disorder: Phenotypic differences between patients with and without comorbid depression. Journal Sleep Research
  3. Mariño et al (2025), Audiovisual analysis of the diagnostic video polysomnography in patients with isolated REM sleep behavior disorder, J Neurol.
  4. Tafelmeier et al (2025), Time course of hospitalizations in patients with heart failure and chronic obstructive pulmonary disease around sleep-
    disordered-breathing diagnosis, Sleep Breath.
  5. Pellegrini et al (2025), Behind Closed Eyes: Understanding Nightmares in Children and Adolescents with Autism Spectrum Disorder – A Systematic Review. Neurosci Biobehav Rev.
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