Study found children who had ongoing shorter sleep at time points between 6 months and 7 years old were associated with depression between 13 and 22 years old
Children who experience persistent sleep issues throughout their younger years may have a greater risk of developing depression in adolescence, a new study suggests.
Led by Dr Isabel Morales-Muñoz at the University of Birmingham, research published in European Child & Adolescent Psychiatry found that persistent shorter sleep, affecting 2% of a long-term cohort of children, led to around twice the risk of developing depression between the ages of 13 and 22.
The research team, supported by our Biomedical Research Centre worked with a large long-term dataset of 15,589 young people born in the South West of the UK and controlled for factors including socioeconomic and parental health factors. The dataset was then broken down for those that had provided information about sleep duration during childhood, and participants who had taken a mental health survey between 12-22. Of the wider group of participants, 8,771 had been surveyed and around 80% (n=5411) had the lowest level of depressive symptoms, while 4.5% (n=308) had ‘persistent’ higher depression symptoms.
Among 1,756 participants with full information on sleep and depressive symptoms in adolescence, the children who were regularly getting ‘persistent shorter nighttime sleep’ as a lowest of four quartiles had higher rates of depression. The team calculated the likelihood (odds ratio) that persistent short sleep would lead to depression of 1.99 – meaning that the odds of developing depression, albeit small, was twice as likely.
Dr Isabel Morales-Muñoz, from the University of Birmingham and lead author of the study, said: “We found that the small numbers of children who had persistently shorter sleep across childhood saw some increased risk of developing depression during adolescence. A doubling of odds might sound like a lot, but we saw that persistent sleep issues only affected a small number of children who took part in the study and that there was still only a small percentage of children who went onto experience persistent depressive symptoms.
“Sleep is also an element of childhood that is possible to improve without needing medical interventions, and efforts to address persistent poor sleep during childhood will have a host of benefits including addressing any potential mental health risks.”
For example, measures to improve childhood sleep include implementing earlier and consistent bedtimes, reducing screen time before bed, encouraging physical activity during the day, and creating a calm sleep environment. Educating families about healthy sleep habits can also help prevent ongoing sleep difficulties and support mental wellbeing. However, access to the conditions needed for good-quality sleep is not equal or always possible, with factors such as housing, income and neighbourhood environments shaping children’s ability to get adequate rest.
Nighttime sleep duration during the study was from parent reported information taken at 6 and 18 months, 2 ½, 3 ½, 4-5, 5-6, and 6-7 years. The average (mean) sleep during each period was approximately 11 hours, with significantly more variation in younger children. In this period, children who had persistently shorter sleep recorded approximately 9 to 9 ½ hours of sleep across these time periods.
Few other factors accounted for increased odds of later depression. Sex assigned at birth led to a significant increase in risk for female participants, in line with previous findings. Family adversity had a small increased association (OR=1.09), and no other factors had a statistically significant impact on increasing odds.
Does inflammation have a role?
The study also looked at whether inflammation played a role in persistent poor sleep leading to increased odds of depressive symptoms later.
Previous studies from Dr Isabel Morales-Muñoz and also from the wider team within the University of Birmingham’s Institute for Mental Health have investigated the role of specific markers of inflammation during childhood in other mental health conditions. In this occassion, the team investigated whether inflammation following poorer sleep might have a causal effect on the brain during development, leading to a greater susceptibility to depression.
The team found that one inflammatory marker (IL-6) may have some role in this relationship, but not the other marker (CRP) which is a cumulative buildup of chronic inflammation in the body. The findings suggest that IL-6 may have a direct connection to the pathway that leaves adolescents at risk of depression, but the study was not designed to find a causal link between sleep and depression symptoms.
Dr Rebekah Amos from the University of Birmingham who co-authored this study said: “This study advances our understanding of factors that increase young people’s risk for more severe and enduring depression. The findings suggest that chronic poor sleep may contribute to long-term mental health difficulties through biological pathways including inflammation. However, improvements in sleep behaviour and bedtime routines may interrupt this effect.”
This research is part of the Mental Health Mission Midlands Translational Centre’s Mood Disorders Theme, led by the University of Birmingham and funded by the National Institute for Health and Care Research. A key aim of the Mood Disorders’ Theme is to test and validate treatments in depression, and as such this study supports the importance of addressing sleep as a potential strategy for improving and preventing depression.
