When that afternoon energy crash rolls around, you might find yourself wishing for and even indulging in a cozy nap. Whether you are a cat napper or a full 2-3 hour committed napper, you might wonder how your habit influences nighttime sleep, and your overall health. A recent study published Monday in an American Heart Association Journal called “Hypertension” connected napping with an increased risk of high blood pressure and stroke, causing some alarm for nappers everywhere.
The study participants were 24 percent more likely to have a stroke, and 12 percent more likely to develop high blood pressure, even when researchers controlled for other risk factors like type 2 diabetes, high cholesterol, and more. The results contradict some older research, such as this 2019 study that found nappers had a lower risk for cardiovascular issues.
One possible theory explaining the results is that those who nap might be doing so because they have reduced quality or length of overnight sleep, which can be connected to health problems.
“Even though the study’s main focus was napping frequency, and not the assessment of nighttime sleep, it is true that the study participants that had more daytime naps were also more likely to have sleep issues such as insomnia,” says Dr. Alexander Postalian, MD, FSCAI, a cardiologist at the Texas Heart Institute. “Moreover, they were also more likely to be older, have higher relative body weight, history of smoking, diabetes, and high cholesterol. However, the authors did their best to adjust for these confounding issues while drawing their conclusions.”
The link between sleep and hypertension and stroke goes far beyond napping behaviors. Postalian explains that adequate sleep time and high quality reduce the amount of circulating stress hormones which result in better cardiovascular adaptation to aging, scientists think. This means less hypertension and cardiovascular disease. “An important point to make is that we shouldn’t focus only on sleep duration and timing but also sleep quality. Obstructive sleep apnea is a common condition where the individual “chokes” intermittently during sleep due to softening of the throat muscles; this greatly increases the body’s stress response, raising the incidence of high blood pressure, arrhythmias, and other cardiovascular problems,” he says.
Dr. Peter Polos, MD, PhD, FCCP, FAASM, sleep medicine specialist and sleep expert for Sleep Number, recommends taking the study with a grain of salt as there’s much more to it than just napping or not. “In the study, subjects were asked about napping habits four times between 2006 and 2019 and self-reported their napping frequency as ‘never/rarely,’ ‘sometimes,’ or ‘usually.’ The group that usually took naps also smoked cigarettes, drank alcohol daily, and snored. We know that poor sleep is often associated with increased napping. So, the study really shows that taking more naps reflects an increased risk for cardiovascular disease in subjects who likely have additional risk factors.”
If you are hoping to achieve the optimal nap time for better health, Robin M. Tucker, PhD, RD, FAND at Michigan State University’s Department of Food Science and Human Nutrition who studies the relationship between poor sleep on nutrition-related health outcomes, says 20-30 minute naps are best. “They can leave you feeling more alert and better rested. If you need longer naps and don’t have diagnosable sleep issues, then it could be that your sleep hygiene behaviors are causing you problems.”
Dr. Po-Chang Hsu, medical advisor at Sleeping Ocean, adds that naps that are longer than that, such as 30 minutes and beyond, might impact nighttime sleep negatively, especially for older adults more prone to insomnia. But parents of napping children shouldn’t worry that this study is related to their children’s health. “There’s no problem with longer daytime naps in children as they need more sleep for cognitive development, memory consolidation by the brain, building of growth cells, and more.”