Sleep problems in teenagers predict self-harm risk over time

Self-harm in young people is a major public health concern, rates are rising, and the adolescent years presents a critical period of intervention. Another modern challenge facing adolescents is sleep deficiency, with global reductions in total sleep time and inconsistent sleep patterns, and as many as 70% of teenagers getting inadequate sleep. 

Published today in the Journal of Child Psychology and Psychiatry, researchers at The University of Warwick and University of Birmingham have investigated this relationship between multiple measures of sleep problems and self-harm, using data from over 10,000 teenagers from the Millenium Cohort. 

10,000 teenagers, aged 14, were asked about their sleep problems including how long they slept on school days, how long it took to get to sleep, and how often they awoke during the night. They were also asked whether they had self-harmed at 14, a question they were asked again three years later when surveyed at 17 years old. 

Michaela Pawley, PhD Candidate, Department of Psychology, University of Warwick, and first author said: "Using large scale data like this really allows you to explore longitudinal relationships at a population level. In this analysis, we discovered that shorter sleep on school days, longer time to fall asleep and more frequent night awakenings at age 14 associated with self-harm concurrently and 3 years later at age 17." 

"While this is clearly an unfavourable relationship, one positive from this research is that sleep is a modifiable risk factor - we can actually do something about it. If the link between sleep and self-harm holds true and with well-placed interventions in schools and homes, there is a lot we can do to turn the tide." 

The researchers found that sleep problems at age 14 were directly associated with self-harm behaviour at age 14 and again at age 17, showing that teenage sleep can have long lasting impacts on self-harm, and could be an avenue to support teenagers at risk. 

Sleep problems contributed to risk, even when accounting for other factors that have shown to influence self-harm such as age, sex, socio-economic status, previous instances of self-harm, self-esteem and, importantly, levels of depression. Importantly, only sleep was consistently significant when looking cross-sectionally (age 14) and longitudinally (age 17). 

Senior author Professor Nicole Tang, Director of Warwick Sleep and Pain Lab at The University of Warwick added: "Self-harm is one of the leading causes of death among adolescents and young adults. It is a sobering topic. Knowing that poor and fragmented sleep is often a marker preceding or co-occurring with suicidal thoughts and behaviour, it gives us a useful focus for risk monitoring and early prevention." 

The researchers were interested in what could explain this relationship and tested the idea that poor sleep is linked with poorer decision making, which increases your risk of self-harm behaviour. This turned out to not be the case, leaving an open question as to how poor sleep is associated with risk of self-harm. 

Regardless, because adolescence is a critical period of vulnerability and potential prevention for self-harm, this study emphasises that sleep health needs to be prioritised in adolescents. Doing so could have long lasting protective effects.