Worried that too little sleep might be impacting your health? Don’t overdo it. Presenting their findings today to the British Sleep Society, researchers outlined a stark conundrum: lack of sleep can more than double the risk of death from cardiovascular disease, too much sleep doubles the risk for non-cardiovascular-related deaths.

Studying the sleep patterns of over 10,000 civil servants—and adjusting for myriad factors including blood pressure, employment level, and age—the researchers found that both increases and decreases in hours-per-night over a sustained period of time upped one’s chances of dying. Though the risks associated with less sleep have long been known, increased mortality rates tied to more sleep came as a surprise: “No potential mechanisms by which long sleep could be associated with increased mortality have yet been investigated,” noted Professor Francesco Cappuccio.

The solution? Sleep 7 hours a night and do it consistently. Sounds . . . awful.—Abby Seiff