Lack of sleep in teens leads to extra stress and poor functioning.
Nearly 70% of American adolescents lack sleep. Shortage of sleep and other difficulties with sleeping can lead to cognitive problems and poor physical health over time.
Now it seems that sleep problems or sleeping for too long can make adolescents more reactive to stress, potentially affecting academic performance, behavior and health.
The key could lie in the hypothalamic-pituitary-adrenal axis, or HPA axis, a part of the neuroendocrine system that controls reactions to stress and regulates many body processes.
The association between sleep and the HPA axis has been studied in both children and adults.
However, what happens during puberty, a key period of development when both sleep and the HPA axis are undergoing significant changes, is unclear.
Sylvie Mrug and colleagues, from the University of Alabama in Birmingham (UAB) and Arizona State University, wanted to investigate the relationship between sleep and reactivity to stress in adolescents, focusing on the HPA-axis activity.
Study aims to help urban, black teens
They 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 compared the results based on gender.
The selected participants were 84 urban, black adolescents with an average age of 13 years. This population was chosen because a lack of sleep was already known to have a negative impact on their functioning.
The researchers hoped that the results would prove helpful for this population.
The young people completed the children's version of a common stress test, the Trier Social Stress Test, to measure their physiological responses to stress.
The test involves speaking and computing mental math problems in front of an audience. Cortisol levels were assessed by comparing saliva samples before and after the test.
Participants and their parents then reported on the adolescents' sleep habits, including bedtimes, waking times and any sleep problems, such as insomnia, daytime sleepiness and general sleep quality, during a regular week.
Longer sleep duration, higher cortisol release under stress
The sleep problems most commonly reported were 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.
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.
Additionally, cortisol release was higher among females with sleep problems than males, suggesting that adolescent girls may be particularly affected by disrupted and poor quality sleep.
The higher cortisol measurements in adolescents who were experiencing sleep problems was not unexpected.
However, as Mrug explains:
"We were [...] surprised that longer sleep duration predicted a stronger cortisol response, because previous studies linked shorter sleep duration with higher cortisol levels. Generally, less sleep is related to poor outcomes, not the other way around."
This could be because sleeping for longer does not necessarily mean higher-quality sleep, but it may indicate other sleep problems, at least among urban adolescents.
Mrug adds that the findings are important, because the enhanced and prolonged activation of the HPA axis in response to stress could lead to further health problems.
The young people who were studied may be negatively affected by poor sleep more than other groups due to uncontrollable stress related to community and school violence, she says.
She adds, "We want to do all that we can to understand ways we can help ensure better cognitive, emotional and physical health outcomes for these adolescents."
Medical News Today recently reported that single mothers are most likely to lack sleep.