Americans' chronic lack of sleep, says the CDC , is a "public health crisis." And there's plenty o research to prove it. As The New York Times puts it, "In the last year or two, an obsessive fixation on getting sleep — not just any sleep, but good sleep — has crept into our public consciousness." Personal gadgets promising to track sleep patterns for rest-prioritizing individuals have proliferated. Right now, WNYC's Clock Your Sleep program is monitoring sleep patterns of large volunteer populations to better understand the duration and quality of our sleeping patterns.

Sleep is fertile grounds for obsession in part because it's an extremely complex subject. For instance, we're usually told that naps are good. But a new study from Cambridge University found that people who frequently take day-time naps of an hour or longer tend to die younger than those who forego mid-day sleeping.

But it's probably not the naps themselves that are causing the problem. The team thinks it's most likely an underlying health condition that is both causing fatigue and inspiring the naps and shaving years off napper's lives, Medical Daily reports. Short siestas of about 30 minutes, on the other hand, were not associated with any health problems and can be helpful for providing a boost of energy during a midday lull.

To arrive at these findings, the researchers followed around 16,000 British men and women aged 40 to 79 over the course of 13 years. The researchers asked them about their napping habits, Medical Daily describes, and categorized the participants into three groups based on those data: people who napped for more than an hour per day, people who napped for less than an hour per day and people who did not nap at all. They controlled for other factors like gender, socioeconomic status, alcohol and mental illness such as depression.

At the end of the study, people who napped for more than an hour were 32 percent more likely to have died than non-nappers, the authors report. As Medical Daily reports, the cause of those deaths varied but included heart disease, cancer and respiratory illness. In other words, the researchers aren't sure what the link between long naps and death risk is, but they think that excessive day time fatigue could likely be indicative of an underlying health problem that their study was not able to tease out.

So, if you like a short nap midday, don't worry. But if you find yourself dropping off for long, sleepy stretches in the long afternoon, you might check if there's some reason your body needs a rest.