There is an abundant—and ever-growing—body of evidence that indicates sleep plays an important role in cardiovascular health. Poor sleep is associated with a range of heart problems, including high blood pressure and increased risk of heart attack. Now, new research shows a link between insomnia and heart failure. Nearly 6 million adults in the United States suffer from heart failure, according to the Centers for Disease Control. Heart failure is directly responsible for more than 55,000 deaths every year, and is a contributing factor to hundreds of thousands more deaths in the U.S. annually.
Researchers in Norway conducted a large-scale study of the relationship between insomnia and heart failure, and found that the presence of several symptoms of insomnia is associated with a dramatically elevated risk of developing heart failure. The investigation included more than 54,000 men and women between the ages 20-89. All were participants in a large-scale public health study in Norway. At the study’s outset, none of the men and women included had known symptoms or evidence of heart failure.
Researchers collected data on participants’ sleep, including detailed information on three common symptoms of insomnia:
- Difficulty falling asleep
- Difficulty staying asleep
- Waking feeling un-refreshed—a sign of non-restorative sleep
Researchers also gathered information on other aspects of health, including risk factors for cardiovascular disease. Participants were then monitored over a period of more than 11 years. Over that period of time, slightly more than 1,400 people developed heart failure. Researchers analyzed data to identify a possible relationship between the incidence of heart failure and insomnia symptoms, while controlling for other factors that could influence the risk of heart disease, including age, cholesterol and high blood pressure, body mass index, history of heart problems, and alcohol and tobacco use. They found that insomnia was associated with a higher risk of heart failure:
- People who experienced insomnia symptoms had a higher risk of developing heart failure than those who did not experience insomnia symptoms.
- The risk increased for people who had multiple symptoms of insomnia.
- People who experienced all three insomnia symptoms—difficulty falling asleep, difficulty staying asleep, and non-restorative sleep—had more than triple the risk of developing heart failure than those with no insomnia symptoms. People with all three insomnia symptoms also had significantly higher risk of heart failure than those with one or two symptoms of insomnia.
The study results show a strong association between insomnia and heart failure. But they do not provide any evidence to answer the question of whether—or how—insomnia might directly cause heart failure. Additional research is necessary to determine if disrupted sleep plays a causal role in the development of heart failure.
Heart failure occurs when the heart is unable to pump blood effectively at levels that meet the body’s constant needs. This is a serious cardiovascular disease that has no cure. Other research has shown evidence of a link between sleep problems and heart failure, including studies that indicate an increased risk for heart failure among patients with obstructive sleep apnea.
There is also a great deal of evidence that sleep is critically important to heart health, and that disrupted, poor, and insufficient sleep is associated with elevated risk of cardiovascular disease:
- This large-scale investigation, conducted by members of the Norwegian research team responsible for the current study, found people with insomnia at elevated risk for heart attacks. People with insomnia had a 27-45% greater risk of heart attack than those without insomnia symptoms.
- This study showed people who slept fewer than 6 hours a night had a 48% higher risk of heart attack, as well as a 15% increased risk of stroke.
- Sleep disordered breathing—which commonly manifests as snoring, or in obstructive sleep apnea—is associated with higher risk of heart failure, stroke, and coronary heart disease, according to this research.
- Poor sleep is also linked to elevated rates of high blood pressure, an important risk factor for heart attack and heart failure.
Science is still working to get to the root of the relationship between sleep problems and cardiovascular disease. Lack of sleep has been associated with calcium build-up in the arteries, as well as with inflammation and dysfunction of the central nervous system. Definitive answers to the role that sleep plays in cardiovascular disease may well lie in these areas. But the mechanisms by which sleep may influence—or cause—diseases of the heart are not yet well understood. Still, there is little question that maintaining healthy sleep habits, and addressing sleep problems promptly with your physician, is beneficial to your overall health and to heart health in particular.
By Michael Breus, PhD, ABSM