Irregular Sleeping Linked to Greater Risk of OSA, Hypertension

A new study found irregular sleeping was associated with a greater risk of obstructive sleep apnea (OSA), and irregular sleeping combined with OSA was associated with an increased risk of hypertension in a middle-aged population.¹

Investigators, led by Kelly Sansom, PhD, research associate in clinical sleep health at Flinders Health and Medical Research Institute, wanted to learn more about the inter-relationships between sleep regularity, OSA, and health markers. To accomplish this, they leveraged data from the Raine multigeneration prospective cohort study, to evaluate whether irregular sleeping was associated with OSA and hypertension for their cross-sectional analysis.

“The current study shows for the first time that both mildly irregular sleep and severely irregular sleep are associated with approximately double the odds of OSA relative to regular sleep,” wrote the investigators. “Irregular sleep patterns may contribute to circadian disruption and lead to changes in sleep composition and quality.”

According to estimates from the National Council on Aging, OSA affects 936 million adults across the globe. Characterized by partial or complete airway obstruction leading to hypoxemia and multiple secondary effects, patients with OSA are considered to be at an elevated risk of cardiovascular events.^1,2

Although some individuals with OSA have a greater risk of hypertension, the magnitude of this risk varies from individual to individual. Thus, to improve medical approaches, understanding the association between sleep-related factors associated with OSA-related hypertension is crucial. With this in mind, Sansom and team designed their research endeavor as an analysis of these associations using participants' data from the Raine Study, which was a multigeneration prospective cohort study of parents and their children in Perth, Western Australia with 26 years of follow-up data.

After exclusion of those who were not evening or night shift workers, the team identified a cohort of 602 adults for inclusion. This cohort had a mean age of 56.96 years, 60% were female, and 92% were White. Every participant was assessed for OSA via an in-laboratory polysomnography and an apnea-hypopnea index of ≥ 15 events per hour, hypertension (systolic blood pressure ≥ 140mmHg and/or diastolic ≥ 90mmHg), and sleep (wrist actigraphy for ≥ 5 days).

Participants were categorized as either severely irregular, mildly irregular, or regular sleepers. The sleep regularity index scores ranged from 79.98 – 94.8 for regular, 71.12 – 79.98 for mildly irregular, and 9.45 – 71.07 for severely irregular sleep patterns.

Severely irregular sleep was linked to decreased actigraphy-derived sleep duration and poorer self-reported sleep quality when compared to regular and mildly irregular sleep. When compared with regular sleep, mildly irregular and severely irregular sleep was associated with a greater AHI< greater T90, decreased PSG total sleep time, and reduced REM sleep.

Investigators used logistic regressions to evaluate the relationships between sleep regularity index, OSA, and hypertension. They also took into consideration covariates, such as age, sex, body mass index, actigraphy sleep duration, insomnia, depression, activity, alcohol, smoking, and anti-hypertensive medication.

Investigators found participants with mildly irregular (odds ratio [OR], 1.97; 95% confidence interval [CI], 1.20 – 3.27) and severe irregular (OR, 2.06; 95% CI, 1.25 – 3.42) sleep had greater odds of OSA than regular sleepers. Additionally, compared to individuals without OSA and regular sleep, OSA combined with severely irregular sleep had the highest odds of hypertension (OR, 2.34; 95% CI, 1.07 – 5.12; P = .02). Yet, individuals with OSA and regular or mildly irregular sleep did not have an increased hypertension risk (P = .20).

As for covariates, the team found participants with mildly irregular (P = .042) and severely irregular (P < .001) sleep had greater body mass index compared to individuals with regular sleep. Moreover, individuals with severely irregular sleep had lower levels of education attainment, lower income, greater prevalence of current smoking, and greater self-reported symptoms than individuals with regular and mildly irregular sleep.

“These findings suggest that decreased sleep regularity may be associated with socioeconomic disadvantage and behaviours associated with negative health outcomes,” investigators wrote.

Investigators called attention to limitations imposed by the nature of actigraphy measurement conducted in the study. As a result of only calculating a minimum of 5 overlapping nights, some individuals might not have had a weekend or weekday overlap and the team was unable to identify the standard deviation in sleep timing as it requires > 7 nights of actigraphy.

“These findings suggest that sleep regularity, as assessed by the [sleep regularity index], may be an important modifier of the known association between OSA and hypertension,” investigators concluded.

^References

1. ^{Kelly Sansom, Amy Reynolds, Daniel Windred, Andrew Phillips, Satvinder S Dhaliwal, Jennifer Walsh, Kathleen Maddison, Bhajan Singh, Peter Eastwood, Nigel McArdle, The interrelationships between sleep regularity, obstructive sleep apnea and hypertension in a middle-aged community population, Sleep, 2024;, zsae001, https://doi.org/10.1093/sleep/zsae001}
2. ^{Ling, V. Sleep Apnea Statistics and Facts You Should Know. Ncoa. https://www.ncoa.org/adviser/sleep/sleep-apnea-statistics/. Accessed January 15, 2024.}