Apneic Sleep, Insufficient Sleep, and Hypertension

Abstract

These changes progressively increase from lighter to deeper stages of NREM, i.e. sleep stages N1 through N3. BP, HR, cardiac output and peripheral vascular resistance all decrease in NREM stages 1 through 3 10,11 . Thus, BP normally shows a "dipping" pattern at night 12 . REM sleepIn rapid eye movement (REM) sleep, there is a reduction in tone of the respiratory muscles except for the diaphragm 13 . Simultaneously, a decrease in sensitivity of the central chemoreceptors occurs 14 . Consequently, ventilation decreases to levels even lower than that seen during NREM sleep and PaCO2 levels start to rise. Sympathetic tone increases during tonic REM sleep, with intermittent surges in both sympathetic and parasympathetic activation during phasic REM, with marked BP and HR fluctuations, such that the overall BP and HR in REM sleep are similar to the levels seen during wakefulness 10 . WakefulnessAn "arousal" from sleep is represented by a change in the electroencephalogram for <10 seconds, and if this change is prolonged for 10 or more seconds, it is termed as an "awakening" 15 . During arousals and awakenings from sleep, sudden increases in minute ventilation, HR and BP are noted 16,17 . Some degree of ventilatory "overshoot" occurs in that the increase in respiratory drive during arousals and awakenings is higher than that expected for the PaCO2 level at the time 16 . A rise in sympathetic activity and decline in parasympathetic tone occurs; the consequent rise in BP and HR during arousals and awakenings significantly exceeds baseline wakefulness levels 17 . SLEEP-RELATED BREATHING DISORDERS AND HYPERTENSIONOSA is the most common sleep-related breathing disorder, characterized by repeated complete (apnea) or partial (hypopnea) upper airway inspiratory closure in sleep 18 . The severity of OSA is gauged by the number of disordered breathing events per hour of sleep or recording time on a sleep study (in-laboratory polysomnography or a home sleep apnea test). The events are accompanied by oxyhemoglobin desaturation and sometimes with arousals from sleep. Up to 24% of men and 9% of women between 30-60 years of age are estimated to have OSA in the general U.S. adult population, with some other cohorts showing higher prevalence rates of sleep disordered breathing (SDB) (e.g. 50% of men and 23% of women with moderate to severe SDB in a population-based study in Switzerland) 1, 2 . Mechanisms linking sleep apnea and hypertensionThe chemoreflexes-Whereas in normal sleep, changes in BP are mainly sleep stage dependent, in subjects with SDB, these changes depend on the severity of disordered breathing events 19,20 . Recurrent episodes of cessation of breathing due to upper airway closure or narrowing with accompanying hypoxemia lead to chemoreflex-mediated sympathetic activation 21 . At the termination of the disordered breathing event, an increase in cardiac output occurs, but this is delivered into a constricted vasculature. As a result, intermittent rises in BP as high as 250/110 mm Hg may be noted in individuals with OSA, t...

The relationship of hypertension with obesity and obstructive sleep apnea in adolescents

“…The relationship between obesity, OSA, and HTN has been well studied in adult patients and demonstrates independent relationships amongst the comorbidities 10,12 . The relationship has not been as well studied in pediatric patients; while some prior studies demonstrate that these comorbidities often exist in adolescent patients, 21–23 there is no study that confirms a clear, independent relationship between OSA and HTN, as it does in adult patients.…”

“…While there is an established relationship amongst OSA, obesity, and HTN/EBP, the relative contributions of obesity and OSA individually to the development of HTN/EBP remain unclear. In adults, it has been shown that OSA is the second most prevalent contributor to HTN/EBP after obesity 10–12 . However, the relationship between HTN/EBP and OSA is not clearly established in adolescents 13,14 .…”

Interaction effect of obstructive sleep apnea and periodic limb movements during sleep on heart rate variability

“…Obstructive sleep apnea is known to be accompanied by elevated blood pressure and increased blood pressure variability (Mansukhani, Covassin, & Somers, 2019;Narkiewicz et al, 1998), while the association between PLMS and hypertension is less compelling (Koo, Sillau, Dean, Lutsey, & Redline, 2015;Walters & Rye, 2009). However, in our patients we did not observe appreciable differences between nighttime and daytime blood pressure.…”

Hypertension and Cognitive Decline: Implications of Obstructive Sleep Apnea

“…The impact of treatment of OSA in lowering BP is modest, with a reduction in mean 24-h SBP and DBP of approximately 2–4 mm Hg (20, 86). The BP lowering effects of CPAP are noted in subjects with pre-hypertension and hypertension, and appear to be greater in those with a higher number of hours of device usage and those who are sleepy, comorbid diabetes mellitus, and possibly in those using fixed vs. auto-titrating modes of PAP (87, 88). Studies have suggested that CPAP treatment may reverse non-dipping of BP at night in those with resistant hypertension (89, 90).…”