People who are in a precarious financial position have an increased risk of cardiovascular disease. New research reveals that chronic sleep loss may contribute to this risk in the context of social inequality.
Last year, research featured in the journal Circulation of the American Heart Association explained that individuals with low socioeconomic status are more likely to develop cardiovascular disease than those who are in a less precarious financial condition.
And as recently as April of this year, a study published in The Lancet: Global Health found that people living in low income countries face a higher risk of cardiovascular disease.
But in a new study, researchers affiliated with the Lifepath Consortium — a research consortium aiming to understand better how socioeconomic differences impact health — have gathered evidence that poor sleep may significantly contribute to the risk of cardiovascular disease in people at a financial disadvantage.
The team reports and explains the new findings in a study paper that features in the journal Cardiovascular Research. In the study paper, the researchers outline why they were interested in the potential link between socioeconomic status, sleep duration, and heart disease, explaining that:
"First, individuals who experienced social adversity across the life-course report sleep-related problems more frequently [...] In particular, people working in shifts, living in deprived neighborhoods, or who have experienced adversity in childhood show an increased prevalence of sleep-related disorders. Second, inadequate sleep has been associated with an increased risk of cardiovascular disease."
Poor sleep explains 13.4% of the link in men
In the current study, the investigators analyzed data from a total of 111,205 participants across eight different cohorts from four countries: France, the United Kingdom, Switzerland, and Portugal.
The team split the participants into different socioeconomic categories — low, middle, or high income — based on the participants' occupation, as well as the occupation of each participant's father.
Thanks to medical exams and self-reported measures, the researchers also had access to the participants' history of coronary heart disease and cardiovascular events. The investigators also looked at measures of sleep duration, categorizing them as recommended sleep (6–8.5 hours per night), long sleep (over 8.5. hours per night), and short sleep (fewer than 6 hours per night).
To understand how, and if sleep loss was likely to contribute to cardiovascular problems in people of different incomes, the researchers used mediation analysis, a specialized statistical method.
The researchers' findings indicated that insufficient sleep might play a role in the heightened risk of cardiovascular disease in people of lower socioeconomic status. However, the impact seemed to vary by biological sex.
The researchers note that short sleep likely explains 13.4% of the link between occupations associated with lower socioeconomic status and coronary heart disease in men.
Although women in lower socioeconomic groups also get heart disease, it does not appear to be linked to sleep in the same way as in men. The researchers hypothesize that this may be because most women already face a much higher burden of responsibilities outside of their professional occupation that independently affects their sleep and their health.
According to study co-author Dusan Petrovic from the University Centre of General Medicine and Public Health in Lausanne, Switzerland, "Women with low socioeconomic status often combine the physical and psychosocial strain of manual, poorly paid jobs with household responsibilities and stress, which negatively affects sleep and its health-restoring effects compared to men."
Based on the study findings, the researchers argue that societies must address many issues that lie at their cores in order to help every single one of their members to achieve adequate sleep as much as possible.
"Structural reforms are needed at every level of society to enable people to get more sleep," advises Petrovic.
"For example, attempting to reduce noise, which is an important source of sleep disturbances, with double glazed windows, limiting traffic, and not building houses next to airports or highways."