Longitudinal sleep characteristics and hypertension status: results from the Wisconsin Sleep Cohort Study

Abstract

Aims: Sleep characteristics such as short sleep duration or sleep-disordered breathing are established predictors of hypertension. However, few studies have used in-lab polysomnography with a longitudinal design to measure how hypertension is associated with different sleep stages over time. The purpose of this study is to examine whether hypertension is associated with the longitudinal course of sleep quality over time.

Methods: The current study evaluated data from the Wisconsin Sleep Cohort Study, which consists of 1525 adults in a community-based population of middle-aged to older adults followed for approximately 12-25 years. Sleep characteristics were objectively measured using polysomnography and subjectively assessed using a self-report questionnaire on insomnia complaints. We used linear mixed-effects regression models and cumulative logit models to assess whether the interaction of hypertension and time is associated with objective and subjective sleep.

Results: We found people with hypertension exhibited a greater decline in total sleep time in rapid eye movement sleep (%) over time than those without hypertension (P < 0.05). Individuals with hypertension had less decline in % N3 sleep over time than those without hypertension (P < 0.05). Among the subjective insomnia complaints, our findings indicate hypertensive individuals have a higher probability of having higher levels of 'difficulties in falling asleep' compared with people without hypertension.

Conclusion: These findings suggest that hypertension is associated with modified longitudinal changes of objective and subjective sleep characteristics.

Figure 1.. Linear association between time and sleep characteristics by hypertension over time

Note: Models were adjusted for age, sex, body mass index, apnea hypopnea index, continuous positive airway pressure use, diabetes, heart failure, and current smoker. Meaningful differences in total sleep time in rapid eye movement (REM) sleep (%) and N3 by change in time and hypertension status were observed. People with hypertension showed a greater reduction in total sleep time in REM sleep (%) than those without hypertension (p <0.05). People with hypertension had an increase in total time in N3 by time, whereas people without hypertension had a decrease in N3 (p <0.05). Total sleep time (min) increased over time but did not differ by hypertension status. The rate of change in sleep efficiency differed by hypertension but not over time. The rate of changes in total sleep time in N1 and N2 and wake after sleep onset (min) did not differ over time nor by hypertension status.

Figure 2.. Probabilities of subjective insomnia complaints categories by time and hypertension

Note: Y axis indicates the probability of being in one or more subjective insomnia complaint category. The X axis indicates time. The model was adjusted for age, sex, body mass index, apnea hypopnea index, continuous positive airway pressure use, diabetes, heart failure, and current smoker. In the hypertension group, the probabilities of indicating “never” or “rarely” increased over time, whereas the probabilities of being in “sometimes,” “often,” “almost always” decreased over time. However, the probabilities of being in one category did not change over time in individuals without hypertension.