Saturday, February 16, 2013
Auditorium/Exhibit Hall C (Hynes Convention Center)
Background: Sleep deprivation is a commonly experienced stressor during adolescence . Recent studies have found associations among sleep patterns and the hypothalamic pituitary adrenal (HPA) axis and its end product cortisol: adolescents who slept more had steeper declines in diurnal cortisol throughout the day, which is considered normative and healthy (Zeiders, Doane, and Adam, 2011). Therefore, I sought to answer two primary research questions: 1) what are the concurrent associations between diurnal cortisol and sleep during the first semester of college; 2) is the change in sleep over the transition to college associated with cortisol during the first semester of college?
Methods: In a sample of 82 adolescents, sleeping patterns and diurnal cortisol rhythms were assessed twice: once during the spring semester of participants’ senior year in high school, and once during the fall semester of their freshman year in college. Subjects provided saliva samples and diary reports five times a day for three days; samples were taken at wake-up, thirty minutes after waking, two random times throughout the day, and at bedtime. Cortisol variables included the size of the cortisol awakening response (CAR), the area under the curve (AUC), and the slope of participants’ diurnal cortisol curves. To analyze sleep, participants also wore the Actiwatch Score (Phillips Respironics, Inc) while they completed the study. The Actiwatch is a wrist-based accelerometer that quantifies movement across the waking day and during sleep. Two sleep parameters were used in the analyses: sleep duration, and sleep efficiency.
Results: Ordinary least squares regression analyses were run predicting each of the diurnal cortisol parameters from sleep duration and efficiency. Several covariates were included in the models because of their known associations with cortisol or sleep: sex, race/ethnicity, caffeine, nicotine and oral contraceptive use. Separate models were run for sleep duration and efficiency because of their high levels of collinearity (r = .520, p<.01). Cross sectional models (Table 1 and 2, Model 1) revealed that sleep duration was associated with a smaller CAR (β=-.123, p<.05), lower AUC (β=-4.531, p<.01), and steeper cortisol slopes (β=-.016, p<.05), while sleep efficiency was not associated with the cortisol diurnal rhythm. Longitudinal analyses where baseline sleep was controlled indicated that it was concurrent sleep duration rather than the change in sleep duration that was associated with the cortisol parameters. Neither concurrent nor past sleep efficiency was associated with cortisol.
Conclusion: These results revealed that sleep duration was associated with diurnal cortisol rhythms even when accounting for baseline sleep quality. These findings suggest that current sleep behavior and cortisol rhythms are associated during the first semester of college and may be important indicators of every day physiological stress activity and regulation of healthy behavioral patterns across the transition to college.
Methods: In a sample of 82 adolescents, sleeping patterns and diurnal cortisol rhythms were assessed twice: once during the spring semester of participants’ senior year in high school, and once during the fall semester of their freshman year in college. Subjects provided saliva samples and diary reports five times a day for three days; samples were taken at wake-up, thirty minutes after waking, two random times throughout the day, and at bedtime. Cortisol variables included the size of the cortisol awakening response (CAR), the area under the curve (AUC), and the slope of participants’ diurnal cortisol curves. To analyze sleep, participants also wore the Actiwatch Score (Phillips Respironics, Inc) while they completed the study. The Actiwatch is a wrist-based accelerometer that quantifies movement across the waking day and during sleep. Two sleep parameters were used in the analyses: sleep duration, and sleep efficiency.
Results: Ordinary least squares regression analyses were run predicting each of the diurnal cortisol parameters from sleep duration and efficiency. Several covariates were included in the models because of their known associations with cortisol or sleep: sex, race/ethnicity, caffeine, nicotine and oral contraceptive use. Separate models were run for sleep duration and efficiency because of their high levels of collinearity (r = .520, p<.01). Cross sectional models (Table 1 and 2, Model 1) revealed that sleep duration was associated with a smaller CAR (β=-.123, p<.05), lower AUC (β=-4.531, p<.01), and steeper cortisol slopes (β=-.016, p<.05), while sleep efficiency was not associated with the cortisol diurnal rhythm. Longitudinal analyses where baseline sleep was controlled indicated that it was concurrent sleep duration rather than the change in sleep duration that was associated with the cortisol parameters. Neither concurrent nor past sleep efficiency was associated with cortisol.
Conclusion: These results revealed that sleep duration was associated with diurnal cortisol rhythms even when accounting for baseline sleep quality. These findings suggest that current sleep behavior and cortisol rhythms are associated during the first semester of college and may be important indicators of every day physiological stress activity and regulation of healthy behavioral patterns across the transition to college.