NEIGHBORHOODS AND SLEEP HEALTH
Sleep, a modifiable health behavior, is increasingly recognized as integral for optimal health and well-being. One-third of Americans report obtaining <7 h of sleep: an insufficient amount according to expert consensus panels. Highly prevalent sleep disorders such as sleep apnea and insomnia are underdiagnosed and a pressing public health burden. Additionally, there are substantial disparities in sleep health; insufficient sleep and unrecognized and undertreated sleep disorders are highly prevalent among racial/ethnic minorities and lower socioeconomic status populations who disproportionately reside in under-resourced neighborhoods.
In this chapter, we first present a theoretical justification for the link between neighborhoods and sleep health, review current literature on the neighborhood determinants of sleep among children and adolescents, followed by a separate section on neighborhoods and sleep among adults. We conclude with opportunities and challenges for advancing the research on neighborhoods and sleep health and their implications for developing interventions and reducing health disparities.
THEORETICAL JUSTIFICATION FOR NEIGHBORHOODS AND SLEEP HEALTH
As part of the emerging literature on the social determinants of sleep health, one active line of research investigates the neighborhood factors that are associated with sleep health across the life course. The high prevalence of poor sleep health, particularly among vulnerable populations, is associated with neighborhood features such as noise disturbances, crime, crowding, excess light, and social isolation; these same factors are also associated with poor health outcomes. The theoretical rationale for such an association is rooted in an evolutionary understanding of sleep as being highly contextually dependent. When an external threat puts a sleeping individual at risk, we can expect sleep to be affected through a reduction in sleep quality or duration to minimize the time vulnerable to threats. Thus, the study of sleep health must embrace a socioecological model in which neighborhood factors are a key component.
Urbanicity and population density
Infants, children and adolescents living in more urban areas and/or areas with higher population density have shorter sleep durations, higher odds of inadequate sleep, and higher rates of obstructive sleep apnea than do children living in less urban or dense areas.
Neighborhood socioeconomic status (NSES)
Low NSES and related measures of neighborhood disadvantage are consistently associated with worse sleep health among both children and adolescents. Children and adolescents living in disadvantaged neighborhoods have shorter nightly sleep durations and greater odds of inadequate sleep than do children and adolescents living in more advantaged neighborhoods. Notably, one recent study of children ages 5–10 years living in urban California counties found that children living in neighborhoods with 40- year histories of consistently high poverty have higher odds of inadequate sleep than children living in neighborhoods with consistently low- or moderate-poverty trajectories; the same study finds that current neighborhood poverty is not associated with sleep adequacy. Additionally, adolescents living in more disadvantaged neighborhoods have more variable sleep times and more sleep problems than those living in more advantaged neighborhoods. Finally, obstructive sleep apnea is also substantially more common and the sleep apnea severity is greater among children living in disadvantaged neighborhoods compared to more advantaged areas.
Neighborhood access to physical activity
The association between neighborhoods and sleep may partially operate through the promotion of physical activity, which is necessary for good sleep. Using data from the National Survey of Children’s Health, including waves from 2003, 2007, and 2011–2012, Singh and Kenney found that children ages 6–17 years residing in neighborhoods with fewer amenities—such as a lack of parks/ playgrounds, recreation/community center, or access to a library/bookmobile—had higher odds of inadequate sleep than their peers living in neighborhoods with these amenities. A smaller study of adolescents living in the Southeast found that recreation facilities located closer to the adolescent’s home lead to higher physical activity, which in turn predicted more daily sleep minutes, better-quality sleep, and less variability in sleep schedules. Relatedly, sleep is more variable for adolescents living on busier streets.
Neighborhood violence and safety concerns
Exposure to violence within the neighborhood may also impact sleep. Concerns about violence and crime or exposure to community violence are associated with a range of sleep problems and inadequate sleep among children and adolescents. Similarly, concerns about school and community violence are associated with poorer sleep quality in a sample of adolescents living in the Southeastern United States, with stronger associations for girls than boys. In less violent settings, girls slept longer each night than boys but in violent contexts there was no sex difference in nightly sleep duration. Finally, acute exposure to violent events is associated with delayed sleep timing and shorter duration.Using a rigorous within person study design in a small sample of adolescents, Heissel et al. found that adolescents go to sleep 30 min later and sleep for 39 min less on the night after a violent crime occurred within half a mile of their home.
NEIGHBORHOOD FACTORS ASSOCIATED WITH ADULT SLEEP
Social characteristics of the neighborhood environment (e.g., social cohesion, safety, violence, disorder) are associated with sleep duration, daytime sleepiness, sleep difficulties and a sleep quality among adults. Adverse neighborhood social environments—those low in social cohesion and high in violence and disorder—are associated with sleeping between 7 and 11min less per night on average, after adjustment for age and sex. Perceived neighborhood safety and social cohesion are associated with both self-reported and objectively measured sleep duration, with longer sleep in safer and more cohesive neighborhoods.
Inadequate sleep duration and delayed sleep timing
Physical neighborhood features such as artificial light, vehicular traffic and noise related to crowding all impact sleep. Traffic (including air, road, and rail), and other urban noise (such as that of alarms, construction, sirens, etc.) can lead to sleep fragmentation, delay sleep onset or contribute to early awakenings. Bright light exposure from street lights, houses, business and commercial space can similarly impact sleep timing, typically delaying sleep onset (circadian phase delay) . Excess artificial light may depress melatonin secretion, which impacts the initiation of sleep by causing circadian phase delay and prolonging sleep latency. In a US study, those with greater nighttime exposure to outdoor lights had a 28% greater odds of a circadian phase delay. Similarly, those living in areas that are brighter at night (typically dense cities) have a later bedtime . Thus, city dwellers often sleep less than their rural counterparts as a result of these physical features of urban neighborhoods.
An estimated 10% of adults suffer from chronic insomnia with 35% of the adult population experiencing insomnia symptoms annually. Insomnia, a clinical diagnosis, is characterized as difficulty initiating and/or maintaining sleep, awakening too early, with a resulting daytime impairment. Contextual features of the neighborhood likely contribute to insomnia. Living in disadvantaged neighborhoods is associated with insomnia symptoms. Objective measures of insomnia such as a greater period of wake after sleep onset are also associated with neighborhood disadvantage. One possible mechanism underlying the association of neighborhood features with insomnia symptoms may be that crime, noise, disorder promote hypervigilance and lead to increased trouble falling asleep, staying asleep, among other sleep disturbances. Neighborhood physical disorder and low social cohesion are associated with greater odds of difficulty falling asleep among older adults.
Obstructive sleep apnea (OSA)
Neighborhood features which promote obesity, sedentary behaviors and metabolic disease likely increase the risk of OSA. Sleep apnea is highly correlated with obesity, with greater prevalence and severity among the morbidly obese. Neighborhood built characteristics associated with body mass index (BMI) and physical activity levels include walkability, access to healthy food, recreation, street connectivity and green spaces [65,66,79–81]. Living in neighborhoods with lower-rated walking environments is associated with a greater severity of OSA, with stronger associations in persons with obesity. Neighborhood crowding is also associated with OSA, and BMI partially mediates the association.
CURRENT LIMITATIONS AND FUTURE DIRECTIONS
Though recent research has generated a growing body of evidence supporting an important role of neighborhood environment in sleep health, we have identified several gaps in the current literature. Specifically, the field would benefit from more studies that (1) characterize long-term neighborhood conditions, (2) evaluate evidence from quasi- or natural experiments that use statistical methods to strengthen the argument for causality, and (3) use technological advances to objectively measure neighborhood characteristics at a larger spatial scale.
Studying long-term trajectories of neighborhood conditions and sleep
The vast majority of the literature on neighborhood factors associated with pediatric and adult sleep health examined neighborhood conditions at a single time point. Yet neighborhoods are not static and people are mobile, both of which may lead to changes in neighborhood environment that may impact sleep behaviors. Similarly, sleep health may be differently influenced by exposure to neighborhood factors at different points in the lifespan (such as during childhood). However, only a few studies have sought to understand the impact of long-term exposure patterns to neighborhood conditions on sleep. In one study, compared to neighborhoods with historically high poverty, neighborhoods that showed upward mobility over one decade were associated with lower odds of insufficient sleep.
Evaluating evidence from natural experiments and other causal methods
Most of the empirical studies of neighborhood factors and sleep health have relied on observational data. However, observational studies are plagued by residual confounding from individual backgrounds, which limit their ability to make causal inferences. Due to the scarcity of interventional studies that change neighborhood conditions, quasi-experimental studies take advantage of public policy, funding and physical environmental changes to examine the impact of neighborhood factors on health behaviors and related outcomes. Many such studies have provided valuable insight about designing interventions that aim at improving environmental conditions to reduce health disparities related to physical activity and nutrition.
Using technological advances to studying neighborhoods and sleep at a larger scale
Though recent studies have taken advantage of satellite imagery, national exposure maps, and other technologies to investigate environmental exposures associated with health outcomes, these data have been underutilized to understand sleep health. Because many population-based studies have collected both sleep data and participants’ addresses, more large-scale epidemiological studies could link information such as street connectivity, land use, vegetation, environmental pollutants, and outdoor light and noise exposures to participants’ neighborhood.
For example, two recent studies examined satellite measurements of nighttime outdoor artificial light as predictors of sleep health variables and found that a higher level of outdoor light at night was associated with insufficient sleep in Korean adults, and a stronger evening-type orientation in adolescents in Germany. In addition, widespread use of commercial sleep tracking devices may allow objective assessments of sleep on a large-scale population level.
ARE THERE INTERVENTIONS AND POLICIES TO IMPROVE NEIGHBORHOODS AND SLEEP HEALTH?
Substantial evidence demonstrates that adverse physical and social neighborhood environments negatively impact sleep health and likely contribute to sleep health disparities. Thus, there is a clear need for community interventions and policies to improve neighborhood conditions and promote healthy sleep. Governmental agencies (e.g. World Health Organization, US Centers for Disease Control and Prevention) have highlighted the need to improve housing and neighborhood conditions as a strategy to improve health and address health disparities.
Another in the Peruvian Andes showed reduced sleep apnea symptoms with less indoor air pollution by modifying biomass exposure. Cross-sectional data have shown that access to neighborhood green space is associated with a lower risk of short sleep; therefore policies that promote green spaces may also promote healthy sleep. As a result of home and neighborhood structures, exposure to daylight may be limited, thus interventions that include light boxes in the home can be efficacious in community settings for improving sleep.
Author:Lauren Halea, Sarah Jamesb, Qian Xiaoc, Martha E. Billingsd, Dayna A. Johnsone