Sleep and depression – three studies
I have written about sleep before. Here, I present three studies all relating to effects of sleep problems on adolescents and each using a different methodology. In the first, Hoyniak, Whalen, Hennefield, Tillman, Barch & Luby (2022) published “Early Childhood Sleep Problems Predict Increased Risk for the Later Development of Suicidal Thoughts” in Journal of Psychopathology and Clinical Science. They begin by noting that, “Suicidal thoughts and behaviors in youth are an escalating and immediate public health concern.” Here’s more from the abstract:
Research with adults and adolescents has identified sleep disturbances as a risk factor for suicidal thoughts and behaviors, but this has yet to be examined in early childhood. Using a prospective, 17-year longitudinal design, the current study explored the association between early childhood sleep disturbances and concurrent and later suicidal thoughts and behaviors (in separate models) across childhood and adolescence. Results indicate that sleep problems in early childhood are associated with increased probability for suicidal thoughts after age 8, even when controlling for prior and concurrent depression severity. Our findings suggest that early childhood sleep difficulties warrant increased clinical attention and management, as they may contribute to the maintenance and exacerbation of suicidal thoughts over time.
Manczak, Miller, & Gotlib (2022) published “Census Tract Ambient Ozone Predicts Trajectories of Depressive Symptoms in Adolescents” in Developmental Psychology. Exposure to ozone from air pollution has been linked to an increase in depressive symptoms for adolescents over time, even in neighborhoods that meet air quality standards, according to new research published by the American Psychological Association. An APA article about the research notes that:
Ozone is a gas that is produced when various pollutants from motor vehicle exhaust, power plants and other sources react to sunlight. Higher ozone levels have been linked to various physical ailments, including asthma, respiratory viruses and premature death from respiratory causes. This study is the first to link ozone levels to the development of depression symptoms in adolescents over time. Those symptoms may include persistent feelings of sadness or hopelessness, difficulty with concentration, sleep disturbances and thoughts about suicide.
The researchers analyzed data from a previous study about early life stress with 213 adolescent participants (aged 9 to 13 years old) in the San Francisco Bay area. The researchers compared data about the adolescents’ mental health over a four-year period with Census tracts for their home addresses and air quality data for those tracts from the California Environmental Protection Agency.
Adolescents who lived in areas with relatively higher ozone levels showed significant increases in depressive symptoms over time, even though the ozone levels in their neighborhoods didn’t exceed state or national air quality standards. The findings weren’t affected by the participants’ sex, age, race, household income, parental education or socioeconomic characteristics of their neighborhoods. Manczak said. “This really underscores the fact that even low levels of ozone exposure have potentially harmful effects.”
Ozone and other components of air pollution can contribute to high levels of inflammation in the body, which has been linked to the onset and development of depression. Adolescents may be especially sensitive to these effects because they spend more time outdoors.
They concede that the study is correlational and located only in one area of the country.
Yip, Xie, Cham & El Sheikh (2022) published “Linking Ethnic/Racial Discrimination to Adolescent Mental Health: Sleep disturbances as an explanatory pathway” in Child Development. They begin by noting that, “For all humans, sleep is a biological imperative. Despite its biological bases, however, sleep and sleep behavior are influenced by sociocultural contexts (El-Sheikh, 2011). Sleep is important for development, functioning, and health at all points along the developmental lifespan. Yet, sleep is especially elusive for adolescents.” They apply the race-based disparities in stress and sleep in context (RDSSC; Levy et al., 2016) model which “provides a comprehensive and holistic framework for how ethnic/racial discrimination stress and sleep are implicated in health disparities. The RDSSC model proposes that sleep disturbances serve as an intermediary, biological pathway through which ethnic/racial discrimination stress ultimately leads to cascading effects on developmental outcomes. Applied to the current study, sleep disturbance was investigated as an explanatory mechanism linking ethnic/racial discrimination stress to compromised psychological outcomes among youth of color.”
I like this study because they used 350 9th graders (76 Black, 145 Asian, and 129 Latinx) from five urban high schools with high ethnic/racial diversity. The sample was 69% female. The study is longitudinal, starting with retrospective information about their experiences of ethnic/racial discrimination, sleep, and psychological adjustment in the past 6 months. For 14 days, they completed daily diary reports every night before bed on a tablet provided by researchers, then an online posttest. Here are some of their findings:
On days in which adolescents experienced ethnic/racial discrimination, they reported greater same-day nighttime disturbance.
On days in which adolescents had greater daily nighttime disturbance, they also reported more negative mood, anxious mood, rumination, and somatic symptoms the next day.
On days in which adolescents experienced ethnic/racial discrimination, they reported greater same-day daytime dysfunction.
On days in which adolescents had greater daytime dysfunction, they also reported more negative mental health outcomes (i.e., negative mood, anxious mood, rumination, and somatic symptoms) and less positive mood the next day.
On days in which adolescents experienced ethnic/racial discrimination, they reported greater same-day daytime sleepiness.
On days in which adolescents had greater daytime sleepiness, they also reported more negative mental health outcomes (i.e., negative mood, anxious mood, rumination, and somatic symptoms) and less positive mood the next day.
They conclude, “Perhaps the most notable contribution of this study is the investigation of mediated pathways between discrimination and mental health as explained by sleep/wake concerns.” Sleep/wake concerns bleed into daytime activities and have a particularly detrimental impact on mental health.
Although each of these studies provides only a partial view of impacts of sleep, taken together they suggest that sleep problems in early childhood are correlated with suicidal thoughts in adolescence, ozone levels relate to sleep disturbances and depression, and sleep problems mediate some of the effects of racial/ethnic discrimination on mental health.