Occasional naps linked to decreased heart disease, strokes

Q: I take a short nap at my desk a couple of times a week (I use earplugs and a mask), which my podmates love to tease me about. I just read that napping is good for your heart, but they say if you take a nap during the day, you won't sleep as well at night. Who's right?

A: While it's certainly possible that for some people, a midday nap may interfere with the quality of nighttime sleep, it's not a given. In fact, a robust body of research has found numerous benefits of napping, both to physical and mental health.

Napping has been shown to improve mood, increase alertness, improve performance and stave off late-afternoon fatigue. In many cultures, such as with the Spanish “siesta,” the Italian “riposo” and the Japanese “inemuri,” it's an integral part of daily life.

Here in the United States, the benefits of napping have led a growing number of employers encouraging their workers to take advantage of a lunchtime recharge. Some of the larger tech companies have even installed specially designed recliners, called nap pods, which weave the idea of napping into their corporate culture.

Most recently, a study published in the journal Heart has linked the practice of occasional napping to a decreased risk of heart disease and stroke. Researchers in Switzerland analyzed the nighttime sleep, daytime napping and general lifestyle habits of 3,462 adults between the ages of 35 and 75. About 20% of the study participants reported napping once or twice a week. At the end of eight years, the data suggested that those individuals had a lower risk of heart problems than the non-nappers. Interestingly, the same health benefits didn't extend to the most frequent nappers in the study, who researchers said tended to be older men who smoked and were overweight.

The exact reason for the better health outcomes of the occasional nappers aren't known. But inadequate sleep has been linked to a number of health problems, including high blood pressure, depression and heart disease, and the researchers suggested it's possible that occasional napping helps make up for a sleep deficit.

That said, there's an important distinction between a 10-to-20-minute nap in the middle of the day and dropping into deeper sleep for an hour or longer, particularly in the later afternoon. In those cases, not only do you run the risk of waking up thickheaded and groggy, which can take hours to shake off, it's possible for a late-day dive into sleep to interfere with nighttime sleep.

The goal of a nap is to wake up feeling refreshed. To achieve that, you want to limit your nap to less than 20 minutes. That lets you get the rejuvenating benefits of the early stages of non-REM sleep. If you stay asleep much longer, you run the risk of diving into the deeper stages of the 90-minute sleep cycle. Waking up from deeper sleep often leaves you feeling dazed and disoriented, and it can take hours to fully recover.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.