If you need an accurate assessment of your emotional health, look no further than the quality of your sleep. Have an important test coming up? Giving a big talk to your company tomorrow morning? Chances are you’re not sleeping as well as you typically would.
While most kids have fewer of these worries than adults, some unfortunately have to deal with a different type of stressor—violence. Previous work has shown that kids exposed to violence report significant sleep disturbances compared to non-abused children. It’s thought that witnessing or experiencing a violent event causes increased vigilance due to the perception that one’s safety is at stake, resulting in disturbed sleep. Most of these studies, however, employed subjective (self-reported) sleep quality measures, which can be unreliable.
A study by Jim Spilbury and colleagues published last month in Sleep Medicine set out to clarify the association between violence and sleep quality in children by adopting both longitudinal and objective measures. The authors hypothesised that different forms of violence, such as being physically assaulted versus witnessing a homicide, would affect certain sleep characteristics differently.
The researchers recruited 46 children between the ages of 8 and 16 years from a community-based violence intervention program. Measures were taken at two time points: baseline (within 7 weeks of the violent incident) and after a 3-month follow-up.
At each time point, participants wore an actigraph for one week—a wristwatch-like device that uses movement to determine when individuals are asleep. Five measures of sleep disturbance were extracted from the actigraph: bedtime, sleep duration, sleep efficiency (percentage of time actually asleep while in bed), the amount of time awake at night after initial sleep onset, and sleep duration variability over the week.
Participants also completed two surveys: the Recent Exposure to Violence Scale (which assessed a range of violent events in the kids’ neighbourhood, school, and home over the past year), and a self-reported measure of lingering trauma after a stressful event. A parent of each participant also reported on their child’s sleep quality.
The type of violence experienced by participants varied. Family violence was witnessed by 57 per cent of the children, community violence by 43 per cent, and 41 per cent had suffered physical assault themselves.
Two particular types of violence stood out to researchers in terms of their association with sleep disturbance. Controlling for relevant confounders (such as age, gender and family income), individuals who were physically assaulted had a shortened sleep duration (by 35 minutes on average), exhibited almost three times as much wake time after sleep onset, and 6 per cent lower sleep efficiency than kids who did not experience physical assault. These effects were also seen three months later at follow-up.
On the other hand, children who witnessed a homicide had twice as much wake time after sleep onset, greater night-to-night variability in sleep duration, and more self-reported sleep problems than kids who had not witnessed a homicide. These findings, however, did not persist at follow-up.
It’s not clear why different violent experiences are associated with different objectively- and subjectively-measured sleep outcomes. The researchers suggest that, perhaps, persistence of the sleep disturbance in those who were physically assaulted, as opposed to those who witnessed a homicide, reflects how the former may be perceived as more damaging to one’s personal sense of safety, resulting in greater vigilance and nighttime arousal.
Although this was only a pilot study, its implications for public health and awareness are extremely important. Significant research over the past decade suggests that disturbed sleep in children and adolescents is associated with elevated inflammation, increased prevalence of obesity, and behavioural problems, although the causal relationship between these variables and poor sleep quality is difficult to determine. Interestingly, the researchers found no relationship between parent-reported sleep quality and the participants’ actigraphy measures, suggesting that many parents may not be aware of their children’s sleep difficulties.
While addressing a child’s emotional needs after exposure to violence is clearly important, this study suggests that assessing physical health, such as objectively measuring sleep, is also necessary to assess one’s well-being. After all, disturbed sleep may tell a whole different story of which a parent—or a child, for that matter—may not even be aware.
Spilsbury, J., Babineau, D., Frame, J., Juhas, K., & Rork, K. (2014). Association between children's exposure to a violent event and objectively and subjectively measured sleep characteristics: a pilot longitudinal study Journal of Sleep Research, 23 (5), 585-594 DOI: 10.1111/jsr.12162
Post written by Jordan Gaines Lewis, a PhD student at Penn State College of Medicine studying sleep and obesity in adolescents. She blogs about neuroscience at Gaines, on Brains. Follow on Twitter @GainesOnBrains.