Publication Date

2013-08-02

Availability

Open access

Embargo Period

2013-08-02

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Psychology (Arts and Sciences)

Date of Defense

2012-05-09

First Committee Member

Patrice G. Saab

Second Committee Member

Maria M. Llabre

Third Committee Member

Judith R. McCalla

Fourth Committee Member

Frank J. Penedo

Fifth Committee Member

Nicholas Myers

Abstract

In adolescents, nocturnal ambulatory blood pressure (ABP) provides a rich and informative picture of cardiovascular health and risk. This study modeled nocturnal ABP taken during one night using multi-level growth modeling. A combination of demographic, daytime, clinical, and sleep related variables were also included as inter-individual predictors of nighttime blood pressure regulation. Adolescents (N = 252) were obtained from three larger studies addressed cardiovascular risk in youth attending public high schools in Miami-Dade County. Participants included in this study completed a baseline medical screening, initial ABP assessment visit and had at least one ABP reading taken during sleep. Within a multi-level growth model, time since sleep was included as a Level 1 variable to establish the pattern of nocturnal blood pressure decline. Next at Level 2, demographic (i.e. race/ethnicity, gender, SES), daytime (i.e., school attendance, substance use, stress encountered during the day), and clinical (i.e. obesity, metabolic syndrome, fitness, parental/family history of hypertension) variables were added as predictors of both the intercepts and instantaneous rates of blood pressure decline. Lastly, in a smaller sample of participants who completed sleep quality measures (N = 101), sleep related variables (i.e. normality of this sampled sleep, sleep environment, sleep disturbances) were added as predictors of instantaneous rates of blood pressure decline. While associated with higher blood pressure at the beginning of sleep; identifying as non-Hispanic Black or Other, having a family history of hypertension and reporting higher stress during the day were associated with faster rates of blood pressure decline during sleep. Similarly, while associated with lower intercepts at the beginning of sleep, identifying as non-Hispanic White and as a girl were associated with slower rates of decline during sleep. While specific racial/ethnic identifications, gender, family history of hypertension and greater stress were related to differing average levels of daytime ABP as expected, sleep appeared to act as a recovery period for these blood pressure differences in this sample of adolescents. This study suggests the importance of sleep within adolescent populations at risk for CVD for whom the reduction of blunted nocturnal decline and prevention of target organ damage is targeted.

Keywords

Nocturnal Ambulatory Blood Pressure; Blood Pressure in Youth

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