Boss yelling at you unjustly, noise from cars driving fast through your neighborhood at night (and the worry that those cars might kill someone), the summer heat or winter cold, and those mice that keep escaping your trap but wreak havoc in your kitchen at night -- the list goes on. These are a few issues faced by poor families in the United States. Do these things "get under the skin" to impact health? Research says they might, and one way they might do this is through their impact on sleep.
There are differences in sleep health based on social factors such as ethnoracial group, education level, and household income. Lower socioeconomic status may lead to poor sleep, but the cause could also flow the other way, with poor sleep or a sleep disorder reducing the potential for educational or work success.
Research done by both our group of researchers at Harvard University and by researchers from other institutions show that short sleep is related to chronic disease risk (obesity, hypertension, diabetes, cardiovascular disease) and dying earlier. The persistence of difference across groups, a social gradient in health, potentially signals modifiable health disparities, or even social injustice.
How might social factors like poverty impact sleep? One simple way to organize these possibilities is to consider the external environmental factors in and outside the bedroom and the internal psychological processes in the brain that directly affect sleep duration and quality. The built environment can help or hinder sleep physiology -- a noisy environment is thought to induce a state of "threat vigilance," constantly attending to stressors. Poorly controlled temperature or high humidity can directly lighten our sleep or cause awakenings. Physiological processes and environmental factors can also work together to impede sleep. An example is poor sleep quality due to stress in a rodent-infested apartment, or keeping the windows closed and locked in a non-air-conditioned bedroom for safety worries. Research by Lauren Hale from Stony Brook University, among others, shows high levels of neighborhood disorder (e.g., unclean, high crime, and noisy) and densely population urban environments are associated with decreased sleep quality and shorter sleep durations. These types of neighborhoods are more likely to characterize the environments of those living in poverty.
One standard argument for the importance of sleep was that all humans spend so much time doing it -- so sleep must be important. Nowadays, a lot of us are not sleeping so much. What most of us are doing with a majority of our waking hours, if we're "lucky enough" to have a job, is working. Having a paying job reduces financial insecurity and chronic disease risk, but work can have some negative impact on sleep. U.S. time use analyses led by Mathias Basner show that longer working hours reduce sleep duration: The longer we work, the less we sleep. Estimates of the number of short sleepers in the U.S. led by Kristen Knutson find that this number has increased over the last several decades -- but only for full-time workers. Short sleep duration is related to increased risk of obesity, diabetes, hypertension, and cardiovascular disease, but being a "labor force participant," as the economists call it, is protective of these chronic disease risks.
What about the social stressors of work? A workplace study of predominantly female nursing home workers observed that having a manager who is open/flexible about work and family needs of their employees, was protective of sleep -- the employees of these flexible managers slept about 30 minutes more per day than employees of less flexible and open managers. In that same cohort, we also saw an hour difference in sleep duration between white and black workers. What explained this difference? Longer working hours predicted shorter sleep, but the strongest factor was nightshift -- women working nightshifts and long work hours are more likely to be sleep-deficient. Thus, this apparent ethnoracial difference in sleep appears to be selection to the nightshift -- arguably not the most desirable shift. Disruption of circadian rhythms, as occurs with nightwork, increases diabetes risk.
Sleep, a powerful source of resilience, is usually noticed most when deficient. In this land of opportunity, poverty seems to have an impact on the opportunity for restorative sleep. One recurring theme of the "Great Recession" is the impact of financial hardship on sleep, stress, and health. A flood of studies investigating this relationship is expected in the coming years. One thing we know right now is that sleep health is socially patterned such that the poorest and most vulnerable in our society are getting less sleep, and lower quality sleep.
The impact of neighborhoods, work and other issues is exacerbated by hours spent in front of television and computer screens. If work start time can't be delayed, watching less television in the evening (and maybe now a little less time on Facebook and the internet in general) may be the best way to get a little more shut-eye. However, a comprehensive response that considers the biological, environmental and social determinants of sleep is needed to address sleep health disparities.
Cassandra Okechukwu is an Assistant Professor of Society, Human Development and Health at Harvard School of Public Health. She is a faculty member of the Advisory Board member of the Harvard School of Public Health Center for Work, Health and Well-being; faculty member at the Harvard Population Center; and faculty member of the Work, Family, and Health Network.
Orfeu M. Buxton, PhD, is Assistant Professor, Division of Sleep Medicine, Harvard Medical School; Associate Neuroscientist, Department of Medicine, Brigham and Women's Hospital; Advisory Board member of the Harvard School of Public Health Center for Work, Health and Well-being; faculty member at the Harvard Population Center; and faculty member of the Work, Family, and Health Network.
This post is part of the HuffPost Shadow Conventions 2012, a series spotlighting three issues that are not being discussed at the national GOP and Democratic conventions: The Drug War, Poverty in America, and Money in Politics.
HuffPost Live will be taking a comprehensive look at the persistence of poverty in America August 29th and September 5th from 12-4 pm ET and 6-10 pm ET. Click here to check it out -- and join the conversation.