Can too much sleep be bad for you?

New research suggests more isn’t always better when it comes to sleep. A study published in the Journal of the American Heart Association found people who slept 10 hours a night were 30 percent more likely to die prematurely than those who slept for eight hours.

The risk for death from stroke and cardiovascular disease also increased. The paper looked at 74 studies involving 3.3 million people, but it did not settle the question of cause and effect.

CBS News medical contributor Dr. Tara Narula says the study could be showing that people who sleep longer have underlying medical conditions, such as sleep apnea, depression and anemia.

“Could it be that the biology changes with changes in the circadian rhythm by sleeping longer and that’s causing increased inflammation, weakening of their immune system,” Narula said. “Could it be that they have other adverse health behaviors, so people who sleep longer, maybe they don’t exercise as much.”

She noted that socioeconomic factors like unemployment could also play a role in people’s sleep habits and health, so the study leaves “a lot of questions that we still have to answer.”

Most people try to catch up on sleep on the weekends, but Narula says this study is really focused on those who are sleeping long amounts of time day after day, and it’s important to focus on creating healthy sleep patterns for the long term.

“Really what you need to remember is consistent and regular sleep health patterns are important. So a sleep hygiene regimen where you’re going to bed and waking up at the same time, where you have a cool, quiet, dark room, putting your devices away, you’re not drinking caffeine or alcohol right before bed and you’re exercising on a daily basis,” she said.

Dr. Narula says for people ages 18 to 64, seven to nine hours per night is recommended.