A new study of adult twins suggests that the level of socioeconomic deprivation in a neighborhood is associated with the sleep duration of residents.
Results show that increased socioeconomic deprivation was significantly associated with decreased sleep duration across all twins. Further analysis within twin pairs found that this association remained significant after accounting for genetics and shared family environment, indicating a robust relationship.
"These results are a starting point for discussing the impact that neighborhood-level factors have on sleep duration," said principal investigator Dr. Nathaniel Watson, president-elect of the American Academy of Sleep Medicine and professor of neurology at the University of Washington in Seattle, where he is co-director of the University of Washington Medicine Sleep Center and director of the Harborview Medical Center Sleep Clinic. "If we improve upon social deprivation, we may have an opportunity to improve upon habits that influence how long people sleep."
The research abstract was published recently in an online supplement of the journal Sleep and was presented in Minneapolis, Minnesota, at SLEEP 2014, the 28th annual meeting of the Associated Professional Sleep Societies LLC.
The study group comprised 2,202 twin pairs - 1,268 monozygotic pairs and 934 dizygotic pairs - from the University of Washington Twin Registry. The mean age of study subjects was 37 years, and 62.1 percent were female. Mean self-reported nightly sleep duration was 7.4 hours.
Community socioeconomic deprivation was measured using the Singh Index (SI), a composite, area-level measure. The index combines 17 indicators measuring factors such as poverty, income, education and housing.
Watson's research team also found an intriguing gene by environment interaction. As socioeconomic deprivation increased, the total genetic and non-shared environmental variability of sleep duration also went up.
"The more socioeconomically deprived the neighborhood, the more erratic the sleep duration, both shorter and longer than the healthy seven to nine hours per night that we recommend," he said.