Insufficient sleep and sleep disorders are implicated in 4 of the 7 leading causes of death (cardiovascular disease, diabetes, stroke and accidents). Over 40 studies across several decades have documented that sleep duration is a significant predictor of mortality. Insufficient sleep and sleep disorders are also associated with weight gain, obesity, hypertension, dyslipidemia, insulin resistance, depression, cognitive deficits, and many other adverse outcomes. Sleep is an important part of overall health.
My research interests include the broad application of Behavioral Sleep Medicine, including studies of sleep as a domain of health behavior and the development and implementation of behavioral interventions for insufficient sleep and sleep disorders. Specific areas of focus include: (1) adverse cardiovascular, metabolic, and behavioral health outcomes associated with short sleep and/or insufficient sleep, (2) biopsychosocial determinants of short sleep, insufficient sleep, and poor sleep quality, and (3) behavioral interventions for sleep as a domain of health behavior. In summary, it is my belief that we need to better understand the downstream adverse outcomes of insufficient or poor quality sleep, the upstream determinants of sleep and sleep behaviors, and how knowledge of sleep determinants can inform behavioral interventions for adverse outcomes.
1. Adverse cardiovascular, metabolic, and behavioral health outcomes associated with short sleep and/or insufficient sleep
Existing epidemiological and laboratory studies have demonstrated associations between short and/or insufficient sleep and a number of adverse health outcomes. Despite provocative findings, several important questions remain, including: (1) How do existing studies (which often rely on unvalidated survey items or assess sleep deprivation in normal sleepers) generalize to the phenomenon of short sleep as it exists in the population? (2) If short sleepers do show impairments, how are these effects modified by individual differences in need for sleep, ability to sleep, and ability to adapt to decreased sleep? (3) How can we tell the difference between someone who is a “true short sleeper” and someone obtaining insufficient sleep?
I have several ongoing or recently completed studies in this area. For example, I am currently overseeing a multi-phase study of habitual short sleepers (<6 hours) compared to normal sleepers (7-8 hours). The overall goal of the study is to evaluate (1) Subjective and objective sleep and sleep disorders in self-reported short sleepers, (2) Whether short sleepers are, as a group, impaired relative to normal sleepers, (3) Which cardiometabolic and/or cognitive variables differentiate short and normal sleepers, and (4) Potential subgroups within short sleepers, including “true short sleepers” and “impaired short sleepers.” This will allow for the characterization of the phenotype (and potential endophenotypes) of short sleepers for future genetic and epigenetic studies.
This study includes online screening, at-home sleep apnea testing, saliva for DNA, clinical interview, 2-week monitoring with sleep diary and actigraphy, questionnaires assessing sleep, health and psychological factors, ambulatory and in-lab performance tests, neuropsychological testing, overnight in-lab polysomnography, oral glucose tolerance test, assays for metabolic hormones and inflammatory cytokines, and nutritional analysis. Other studies include, for example, secondary analyses of existing national datasets exploring the relative contributions of short sleep vs. insufficient sleep, interactions with insomnia and sleep apnea, etc.
2. Biopsychosocial determinants of short sleep, insufficient sleep, and poor sleep quality
Sleep is an important domain of health behavior that is largely overlooked in the Health Psychology literature. Unlike diet, smoking, exercise, and alcohol, little is known about the determinants of habitual sleep across the biopsychosocial spectrum. This is important, since successful behavioral interventions will need to account for the behaviors, beliefs, attitudes, and environmental factors that determine sleep-related behaviors. Important questions include: (1) How are determinants of sleep associated with social determinants of health in general? (2) What are the habitual sleep-related practices, attitudes, and beliefs that predict healthy sleep? (3) Can health disparities be partially mitigated by addressing sleep disparities?
I have several ongoing or recently completed studies in this area as well. For example, I am working (with collaborators) to develop and publish the first instrument for assessment of sleep-related practices, beliefs and attitudes. This is important because it will give us an understanding of determinants of sleep and help elucidate potential intervention pathways. Developing this measure involved generating pools of items grounded in the Health Belief Model, Theory of Reasoned Action and Transtheoretical Model of Behavior Change, and refining this measure through an iterative process that included input from a panel of experts and members of the community, four focus groups (results in press), and implementation as part of a research study (in preparation). This resulted in a final draft of the questionnaire, which was assessed psychometrically. These results will be published with the initial publication of the questionnaire (manuscript submitted, invited to Social Science and Medicine). These initial data will allow us to evaluate behaviors and beliefs associated with sleep practices. In addition, publication of this questionnaire will allow future studies to expand these findings.
In addition to this study, I worked with collaborators on a study of sleep quality in the Philadelphia area, documenting a “sleep disparity” related to poverty and race. Other ongoing or recently completed projects are documenting how sleep duration and sleep symptoms are associated with various sociodemographic factors (e.g., age, sex, race/ethnicity, marital status, immigrant status, geography), socioeconomic factors (e.g., income, education, food insecurity, access to healthcare), health behaviors (e.g., diet, exercise, smoking, alcohol use), and the role of social stressors (e.g., racism).
Finally, I was first author on the publication that introduced a social-ecological model of sleep and health (the first social ecological model published for sleep), and I am currently working, along with several collaborators at other institutions, to formally introduce a refined version of this model as a framework for future research in the area of sleep at the interface of biopsychosocial factors and health outcomes.
3. Behavioral interventions for sleep as a domain of health behavior
Well-described behavioral interventions exist for a number of sleep disorders. However, no interventions currently exist that address habitual unhealthy sleep habits, except for poorly-applied “sleep hygiene” instructions. Much work is needed in this domain to address these questions: (1) How can knowledge about determinants and outcomes of insufficient sleep translate into successful interventions that target habitual sleep practices? (2) Do behavioral interventions for insufficient sleep produce improvements in behavioral and cardiometabolic domains? (3) How can individual-level interventions be translated into community-level and population-level interventions?
Although knowledge from the aforementioned areas will be important in informing future interventions, work has already begun to address how to develop and implement a strategy for increasing sleep time as a healthy behavior. I have completed a pilot study of 8 individuals in an open-label trial of an 8-week behavioral sleep extension protocol for habitual short sleepers. Pre-post assessments included sleep, psychological functioning, blood pressure, glucose tolerance and insulin resistance, inflammatory markers, metabolic hormones, neurobehavioral performance, objective sleep propensity, polysomnographic sleep, actigraphic sleep, and other measures. Analysis is ongoing, in preparation for a future grant application.
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