NEW YORK – Good sleep habits may in part counteract genetic susceptibility to developing cardiovascular disease, a new analysis has found.
Heart disease kills 647,000 people each year in the US, according to the Centers for Disease Control and Prevention, and both genetic and behavioral factors contribute to its development. Additionally, recent studies have suggested that unhealthy sleep behaviors like insomnia or snoring may be risk factors for cardiovascular disease.
Using data collected by the UK Biobank, researchers from Tulane University and Peking University developed both a healthy sleep score and a genetic susceptibility score for cardiovascular disease for more than 385,000 individuals. Individuals with poor sleep habits and a high genetic susceptibility score were two-and-a-half times as likely to develop heart disease, but healthier sleep habits appear to partially counter this effect, as individuals with high genetic susceptibility scores but good sleep habits had a lower rate of heart disease. The researchers' analysis was published in the European Heart Journal.
"We found that a high genetic risk could be partly offset by a healthy sleep pattern," Lu Qi, the director of Tulane's Obesity Research Center said in a statement. "In addition, we found that people with a low genetic risk could lose this inherent protection if they had a poor sleep pattern."
He cautioned, though, that as this was an observational study, he and his colleagues could not establish causality.
For their analysis, Qi and his colleagues gathered data from the UK Biobank on participants' sleep behaviors alongside their genetic data. The participants provided information on, for instance, whether they considered themselves to be a morning or evening person, how long they typically slept, and whether they had problems with insomnia or snoring and if they had issues with being sleepy during the day. They also gathered data from hospital admission and death registries to assess incident cardiovascular disease, including coronary heart disease and stroke.
Based on those five sleep factors, the researchers generated a healthy sleep score. Overall, 21.8 percent of the 385,292 participants had the highest healthy sleep score of 5, while 37 percent had a score of 4, and 27.9 percent had a score of 3.
Individuals with high healthy sleep scores of 5 had a 35 percent reduced risk of cardiovascular disease and a 34 percent reduced risk of both heart disease and stroke, as compared with individuals with low sleep scores of 0 or 1.
The researchers also generated genetic susceptibility scores for participants based on 74 SNPs linked to coronary heart disease and 10 SNPs linked to stroke in recent genome-wide association studies.
Individuals with high genetic susceptibility scores and poor sleep scores had the highest risk of coronary heart disease, particularly a 2.5-fold greater risk of coronary heart disease and 1.5-fold higher risk of stroke than individuals with low genetic risk and healthy sleep habits.
But while individuals with high genetic susceptibility scores and high healthy sleep scores were also more likely than those with low genetic risk and healthy sleep habits to develop coronary heart disease and stroke, their risk wasn't quite as high as those with both high genetic susceptibility scores and poor sleep score, suggesting that good sleep habits might mitigate genetic risk.
However, the researchers also reported the converse: individuals with low genetic susceptibility scores and poor sleep scores had high rates of coronary heart disease and stroke, indicating poor sleep habits could undo the effects of low genetic risk.
The researchers cautioned that their study has limitations, including that these associations cannot be shown to be causal, that they had to rely on self-reported sleep data, and that their population was largely of European descent. "However, these findings may motivate other investigations and, at least, suggest that it is essential to consider overall sleep behaviors when considering a person's risk of heart disease or stroke," Qi added.