Sleep Epidemiology: Contributions of Social Determinants

from Assistant Professor, Dr. Dayna A. Johnson, PhD, MPH, MSW, MS:

The practice of epidemiology applies to many health outcomes (e.g., cardiovascular disease) and types of risk factors (e.g., social) that form the specific areas within epidemiology (e.g., social, environmental, genetic, etc.). In my research, I employ epidemiologic methods to study determinants and consequences of adverse sleep health and sleep disorders; therefore, I identify as a sleep epidemiologist. As defined in the book, The Social Epidemiology of Sleep, sleep epidemiology is “the study of the distribution and determinants of sleep, sleep-related symptoms, and sleep disorders and the application of this study to improve sleep health and sleep-health related conditions, including studies of how sleep influences health and disease”.¹

Sleep involves a dynamic set of neurophysiological and behavioral states. What I find most interesting about sleep, is that it is a physiologic activity that is necessary for health and well-being – everyone must sleep. Healthy sleep is multidimensional involving adequate sleep duration, continuity or efficiency, appropriate and consistent sleep timing, alertness during wakefulness, and individual satisfaction.²  Sleep and sleep patterns are adapted to individual, social, and environmental demands. Similarly, our sleep is shaped by many factors including social, environmental, and genetic. In my research, I primarily study social and environmental determinants of adverse sleep health.

Racism and Sleep

The current climate in the world is truly affecting how we sleep. Individuals around the world have witnessed the heinous killings of George Floyd, Breonna Taylor, Ahmaud Arbery (which occurred in our home of Georgia) as well as many others. Witnessing such injustices, which are the result of racism – a fundamental cause of health inequities, can cause a state of vigilance, which is particularly salient for racial minorities. These brutal acts can be even more traumatic for the individuals who resemble the victims, which can cause one to ruminate over how that could have been them or their spouse, father, brother, sister, friend, etc. These are vicarious experiences of racism or discrimination, which are known to affect health, and sleep. These experiences can lead to stress, anxiety or depression, which can directly affect sleep and/or indirectly through rumination where someone repetitively go overs thoughts or problems, which can inhibit sleep onset or disturb sleep.

Location and Environment

Racism, discrimination, and stress are just a few of the contributing social factors to the high prevalence of sleep deficiencies among racial and sexual minorities as well as individuals of lower socioeconomic status (SES). Another important social factor to consider is where we live. Our household and neighborhood environments contain features such as light, noise, safety, density, cohesion that are associated with sleep health.³ Residential segregation based on race, immigration status, SES has largely determined the resources within neighborhoods. Historical discriminatory policies, such as redlining, unwarrantedly denied racial minorities (mainly Black/African American or Latinx) in urban areas mortgages to purchase a home or loans to renovate homes. Housing discrimination is considered one of the largest contributors to the wealth gap and these effects have lasted across generations. Additionally, these under-resourced environments often house manufacturing companies that emit pollution into the air as well as traffic which promotes noise and pollution. Air pollution is directly related to a common sleep disorder, sleep apnea.⁴ And, noise and light pollution are associated with less sleep and sleep difficulties.⁵ Emerging data suggests that the neighborhood environment partially explains racial disparities in sleep. It is also important to note, that there is evidence suggesting that racial disparities in sleep are minimized when Black and White individuals – for example live in similar environments; thus, underscoring the effect of place as opposed to race.

Sleep can be considered a privilege.

It is important to consider the person that works multiple jobs due to low wages, or lives in a neighborhood with noise, violence and/or a household with interpersonal violence… how will they sleep? Children exposed to high levels of screen time or those without a regular bedtime routine are placed on a trajectory of sleep deficiencies in adulthood, which is related to poor health outcomes such as obesity, diabetes, cancer, cardiovascular disease, cognitive decline and mortality. School start times are another factor that can affect sleep, particularly for the student who must take the bus across town to school who, therefore, has less opportunity for sleep. As seen during COVID-19, racial minorities and individuals of lower SES are more likely to be low wage essential workers without worker protection such as sick leave, thus leading to fear and anxiety and consequently sleep deficiencies. This is important because sleep is necessary for healing. In general, those of higher SES have better sleep health. However, higher SES racial minorities such as Black or African Americans tend to have worse sleep compared to their lower SES counterparts. It is hypothesized that stress may explain this unexpected gradient, but more research is needed to fully understand this association.

Sleep Equity

The social factors referenced above-racism, discrimination, stress, mood, household and neighborhood environment are all understudied determinants of sleep deficiencies. Sleep is socially patterned, therefore exploring and addressing these factors can help decrease the burden of adverse sleep health and sleep disorders as well as reduce health disparities. Targeting sleep may improve overall health, decrease accidents (occupational and motor vehicle), and improve performance (athletic and academic).

Sleep is critical and everyone deserves it! Therefore, as epidemiologists we can shed light on the social factors that are contributing to sleep disparities and inform the policies and interventions that may improve sleep for all individuals.

Sleep well!

References

1. Duncan DT, Kawachi I and Redline S. The Social Epidemiology of Sleep: Oxford University Press; 2019.
2. Buysse DJ. Sleep health: can we define it? Does it matter? Sleep. 2014;37:9-17.
3. Johnson DA, Billings ME and Hale L. Environmental Determinants of Insufficient Sleep and Sleep Disorders: Implications for Population Health. Curr Epidemiol Rep. 2018;5:61-69.
4. Billings ME, Hale L and Johnson DA. Physical and Social Environment Relationship With Sleep Health and Disorders. Chest. 2020;157:1304-1312.
5. Billings ME, Gold D, Szpiro A, Aaron CP, Jorgensen N, Gassett A, Leary PJ, Kaufman JD and Redline SR. The Association of Ambient Air Pollution with Sleep Apnea: The Multi-Ethnic Study of Atherosclerosis. Ann Am Thorac Soc. 2018.

Dr. Dayna A. Johnson, PhD, MPH, MSW, MS is an Assistant Professor in the Department of Epidemiology. Her research is aimed at understanding the root causes of sleep health disparities and their impact on cardiovascular disease by 1) addressing the social and environmental determinants of sleep disorders and insufficient sleep; and 2) investigating the influence of modifiable factors such as sleep disorders and disturbances on disparities in cardiovascular outcomes.