Sleep is a critical physiological process that allows the body to rest, repair and rejuvenate and it has profound implications for systemic health, particularly the cardiovascular system. Along with diet and physical activity, sleep is a critical pillar of health. Its role extends beyond circadian rhythm regulation to encompass a range of physiological functions critical for maintaining vascular integrity and cardiac function.

Both optimal and poor sleep patterns exert substantial effects on cardiovascular health. In fact, this association was highlighted in 2016 in a Scientific Statement from the American Heart Association.¹ The inclusion of sleep in "Life's Essential 8" checklist, in 2023, emphasizes the role of sleep on maintaining healthy blood pressure (BP), cholesterol levels and body weight, all critical for heart health.

Unfortunately, poor sleep is very prevalent in the general population. About one in three adults in the U.S. are short sleepers (averaging less than seven hours sleep) and less than half report having a good night of sleep every night.

Optimal sleep duration appears to be seven to nine hours per night for adults, based on numerous studies, including a 2017 meta-analysis of 43 studies that revealed a "U-shaped" curve: both short sleep (less than seven hours) and long sleep (more than eight hours) were associated with a greater risk of all-cause mortality.² Studies have consistently shown that persons who achieve optimal sleep duration are less likely to develop cardiovascular diseases and have reduced risk of major cardiovascular events.³

Clinician Takeaways

During nonrapid eye movement sleep stages, heart rate, cardiac output and systemic BP decrease, a phenomenon known as "nocturnal dipping." This adaptive process reduces cardiovascular workload and confers vascular protection by mitigating endothelial stress and promoting arterial compliance. This "dipping" is crucial for maintaining vascular health and reducing the risk of hypertension. Additionally, deep sleep regulates autonomic balance, favoring parasympathetic dominance, which attenuates inflammatory and oxidative pathways that are implicated in atherosclerosis. Additionally, seven to nine hours of sleep has been shown to enhance glucose metabolism and improve regulation of cortisol and other inflammatory markers and hormones, which impact heart health.

Consequences of Poor Sleep

Poor sleep – characterized by insufficient duration, fragmented patterns or pathologic conditions like insomnia and sleep apnea – can have significant detrimental effects on the cardiovascular system. Chronic sleep deprivation disrupts homeostatic processes, leading to heightened sympathetic nervous system activity, hypothalamic-pituitary-adrenal axis hyperactivation and systemic inflammation. These disruptions have multiple downstream effects, including elevating basal BP and contributing to arterial stiffness, thereby increasing the risk of hypertension and cardiovascular morbidity. A 2011 systematic review found that short sleep duration was associated with a 45% increased risk of coronary heart disease.⁴

Quality of sleep, along with duration, is also linked to cardiovascular outcomes. A meta-analysis of seven prospective studies with sample sizes of 2,960 to 487,200 and a mean follow-up of 10.6 years examined the association of insomnia symptoms and cardiovascular disease.⁵ The risk of cardiovascular disease was 16% higher for those with nonrestful sleep, 22% higher for difficulty initiating sleep and 14% higher for difficulty maintaining sleep. Any insomnia complaint was associated with a 13% higher risk.

A more recent study showed that difficulty falling asleep as well as trouble staying asleep more than twice a week were each related to worse cardiovascular outcomes. Of note, life expectancy at age 30 years for individuals with optimal sleep was 4.7 years greater for men and 2.4 years greater for women, vs. those with low-quality sleep.⁶

Obstructive sleep apnea (OSA) is particularly harmful. OSA exemplifies the deleterious impact of disordered sleep on cardiovascular health. OSA results in intermittent hypoxemia and cyclic arousals, which exacerbate oxidative stress and endothelial dysfunction. Longitudinal studies have established strong associations between OSA severity and adverse outcomes such as left ventricular hypertrophy, arrhythmias and ischemic events.⁷ Its prevalence is as high as 40% to 80% in patients with hypertension, heart failure, coronary artery disease, pulmonary hypertension and atrial fibrillation. OSA is strongly associated with increased risks of stroke and heart failure.

Assessment for OSA should be conducted for patients with resistant/poorly controlled hypertension, pulmonary hypertension and recurrent atrial fibrillation after either cardioversion or ablation.⁸

Mechanisms

Five major mechanisms help explain how poor sleep exerts deleterious effects on cardiovascular health.

• BP Regulation: Adequate sleep fosters nocturnal dipping of BP, an essential regulatory mechanism. Conversely, sleep disturbances attenuate this dipping, predisposing individuals to sustained hypertension.⁹
• Inflammatory Signaling: Sleep deprivation activates proinflammatory cytokines, including interleukin-6 and tumor necrosis factor-α, exacerbating vascular inflammation and atherogenesis.¹⁰
• Autonomic Dysfunction: Chronic sleep loss shifts autonomic balance toward sympathetic predominance, characterized by elevated catecholamine levels, increased heart rate and impaired baroreceptor sensitivity, which can result in higher heart rates and arterial stiffness.¹¹
• Glucose and Lipid Dysregulation: Disrupted sleep adversely affects metabolic homeostasis, reducing insulin sensitivity and promoting hyperglycemia and hyperlipidemia.¹²
• Oxidative Stress: Sleep deprivation amplifies reactive oxygen species production, impairing endothelial nitric oxide bioavailability and accelerating vascular aging.¹³

Making a Difference

Sleep is a cornerstone of cardiovascular health. While optimal sleep fosters physiological processes that protect the heart and vascular system, poor sleep undermines these benefits. The profound impact of sleep on cardiovascular health must be recognized and proactive measures taken to ensure restorative, rejuvenating sleep. By integrating awareness of sleep quality into health care strategies, we can reduce the burden of cardiovascular diseases, improving not just lifespan, but health span.

References

1. St-Onge M-P, Grandner MA, Brown D, et al. Sleep duration and quality: Impact on lifestyle behaviors and cardiometabolic health: A scientific statement from the American Heart Association.  Circulation. 2016;134(18):e367-e386.
2. Yin J, Jin X, Shan Z, et al. Relationship of sleep duration with all-cause mortality and cardiovascular events: A systematic review and dose-response meta-analysis of prospective cohort studies. J Am Heart Assoc. 2017;6(9):e005947.
3. Ahmad A, Didia SC. Effects of sleep duration on cardiovascular events. Curr Cardiol Rep.
2020;22(4):18.
4. Cappuccio FP, Copper D, D'Elia L, et al. Sleep duration predicts cardiovascular outcomes: A systematic review and meta-analysis of prospective studies. Eur Heart J. 2011;32(12):1484-1492.
5. Hu S, Lan T, Wang Y, Ren L. Individual insomnia symptom and increased hazard risk of cardiocerebral vascular diseases: A meta-analysis. Front Psychiatry. 2021;12:654719.
6. Li H, Qian F. low-risk sleep patterns, mortality, and life expectancy at age 30 years: A prospective study of 172 321 US adults. J Am Coll Cardiol. 2023;81(8_Supplement):1675.
7. Peppard PE, Young T, Barnet JH, et al. Increased prevalence of sleep-disorderd breathing in adults. Am J Epidemiol. 2013;177(9):1006-1014.
8. Yeghiazarians Y, Jneid H, Tietjens JR, et al. Obstructive sleep apnea and cardiovascular disease: A scientific statement from the American Heart Association. Circulation. 2021;144(3):e56-e67.
9. Gangwisch JE, Heymsfield SB, Boden-Albala B, et al. Short sleep duration as a risk factor for hypertension: Analyss of the First National Health and Nutrition Examination Survey. Hypertension. 2006;47(5):833-839.
10. Irwin MR, Olmstead R, Carroll JE. Sleep disturbance, sleep duration, and inflammation: A systematic review and meta-analysis of cohort studies and experimental sleep deprivation.  Biol Psychiatry. 2016;80(1):40-52.
11. Somers VK, White DP, Amin R, et al. Sleep apnea and cardiovascular disease: An American Heart Association/American College of Cardiology Foundation Scientific Statement. J Am Coll Cardiol. 2008;52(8):686-717.
12. Reutrakul S, Van Cauter E. Sleep influences on obesity, insulin resistance, and risk of type 2 diabetes. metabolism. 2018;84:56-66.
13. Chellappa SL, Vujovic N, Williams JS, Scheer FAJ. Impact of circadian disruption on cardiovascular function and disease. Trends Endocrinol Metab. 2019;30(10):767-779.

Clinical Topics: Diabetes and Cardiometabolic Disease, Prevention, Diet, Exercise, Sleep Apnea

Keywords: Cardiology Magazine, ACC Publications, Sleep, Sleep Deprivation, Diet, Exercise