Exploration of sleep and allostatic load as predictors of future cancer

Cancer impacts millions of people in the United States. Understanding the precursors to cancer is important for prevention efforts. The purpose of this study was to investigate potential relationships between sleep, allostatic load, and future cancer occurrence. A conceptual framework of responses to stress adapted from a model for allostatic load was used to guide this investigation. The framework depicts cognitive-behavioral responses to stress and physiologic responses to stress impacting future disease occurrence. Subjective sleep quality and sleep duration (cognitive-behavioral responses to stress) and allostatic load (physiologic response to stress) were suspected of having an impact on future cancer occurrence. Secondary data analysis of longitudinal data from the Midlife in the United States study of middle aged and older adults in the United States was employed to explore a relationship between sleep and future cancer occurrence, a relationship between allostatic load and future cancer occurrence, a relationship between sleep and allostatic load, and lastly, a possible mediating role for allostatic load in the sleep – future cancer occurrence relationship A nationally representative sample of 806 persons with oversampling for men, older adults, and African Americans was used for analysis. Sleep parameters were measured by the Pittsburgh Sleep Quality Index (PSQI), a scale with 21 items in seven domains. Overall subjective sleep quality and the seven sleep were analyzed in relation to future cancer occurrence and in relation to allostatic load. In addition to the variable for sleep duration found in the PSQI, continuous hours of sleep, categorical sleep duration based on National Sleep Foundation recommendations, and categorical sleep duration derived from the actual data were analyzed in relation to future cancer occurrence and in relation to allostatic load. Allostatic load was comprised of 23 individual measures across seven physiologic domains compiled using a validated bifactor model. Overall allostatic load and the seven physiologic domains were analyzed in relation to future cancer occurrence. Statistical models included individual differences (age, race, gender, education, and income) and other cognitive-behavioral responses to stress (smoking, alcohol use, physical activity, and depression) thought to be related to the three main concepts of interest (sleep, allostatic load, and future cancer occurrence). Of the permutations of sleep duration, categorical sleep derived from the data fit the best. Short sleep duration (7.5 hours per night) was associated with a 2.2 times increase in the odds of future cancer when compared to the referent sleep duration category (5.3-7.5 hours per night). Age was the only other measure to show a relationship with future cancer; each increasing year of age was associated with a 3% increase in the odds of future cancer occurrence. Poor subjective sleep quality was associated with increased allostatic load. Poor subjective sleep quality was associated with decreased hypothalamic-pituitary-adrenal axis domain scores. No relationship was found between subjective sleep quality or the seven sleep domains and future cancer occurrence. No relationship was found between allostatic load or the seven physiologic domains and future cancer occurrence. No relationship was found between sleep duration and allostatic load. Finally, allostatic load did not play a mediating role in the sleep – future cancer occurrence relationship. This analysis demonstrates that sleep is an important facet of health, and should be routinely assessed by Advanced Practice Registered Nurses as a part of health maintenance and guidance about sleep should be offered to adults. In nursing education, sleep problems should be emphasized as a risk factor for health problems