Insufficient sleep and sleep problems contribute to cognitive problems and poor physical health over time. (Representational Image)
Adolescents who experience sleep problems and longer sleep duration are more reactive to stress, which could contribute to academic, behavioural and health issues, a new study has warned.
Insufficient sleep and sleep problems contribute to cognitive problems and poor physical health over time, possibly because of disruptions in a key part of the neuroendocrine system that controls reactions to stress and regulates many body processes - the hypothalamic-pituitary-adrenal axis (HPA axis).
Researchers at University of Alabama at Birmingham (UAB) explored the relationship between sleep and reactivity to stress, specifically as it relates to HPA-axis activity, in adolescents.
The researchers examined two dimensions of sleep - sleep duration and sleep problems from the perspectives of adolescents and their parents, as well as cortisol levels before and after social stress. They also looked at how the results varied based on gender.
"We chose to look at sleep patterns in urban African-American adolescents, due to information we understood from earlier research in the field," said Sylvie Mrug, a professor at UAB.
"This particular population is more likely to experience insufficient sleep, and their functioning is more negatively affected by lower sleep quality, so we knew that finding results for this demographic could be especially important," Ms Mrug added.
The study was conducted on 84 adolescents with an average age of 13. They were given the children's version of a common stress test, called the Trier Social Stress Test, to measure their physiological responses to stress.
This test involves speaking and computing mental math problems in front of an audience. Saliva samples were taken from each participant in order to test cortisol levels before and after the stress test. Participants then reported on their bed times and wake times and any sleep problems, such as insomnia, daytime sleepiness and general sleep quality, during a regular week.
Parents of the adolescents were asked to report on their children's sleep as well.
The adolescents most commonly reported the following sleep problems - the need for multiple reminders to get up in the morning, not having a good night's sleep, feeling tired or sleepy during the day, and not being satisfied with their sleep.
The researchers looked at the cortisol levels of the adolescent participants. Cortisol release during and after the stressful lab test was higher for adolescents who reported more sleep problems and longer sleep duration, and whose parents reported longer sleep duration.
The effects of sleep problems on greater cortisol release during stress were stronger in females than in males, suggesting that adolescent girls may be more sensitive to disrupted and poor quality sleep.
The findings were published online in the journal Physiology and Behaviour.