Did you get enough sleep last night?

No matter who you are or where you live, the researchers behind a massive new scientific study on sleep say they can tell you exactly how much sleep you should get.

The minimum number of hours probably won't shock you, but what's truly surprising is that they realized there's actually a cap on how much sleep healthy people should get, beyond which brain function suffers.

Here are the study (which the researchers claim is the largest real-life sleep study in history), the details, and exactly how much sleep you really need.

How 44,000 real people sleep

Last year, researchers at the Brain and Mind Institute at Western University in Canada asked a massive number of people to track their sleep over a three-day period and then to undergo a series of cognitive and neurological tests. 

What separates the Western University study from others before it, the organizers say, is twofold:

  • that the study focused on real-life conditions, as opposed to the lab, and 
  • the sheer scale: more than 44,000 people volunteered to participate.

"Obviously there have been many smaller studies of people in laboratories," explained neuroscientist Adrian M. Owen, who led the study. "But we wanted to find out what sleep is like in the real world. How do real people sleep? How much sleep do they get and what effect is it having on their brain?"

After synthesizing the data, from a total of more than 132,000 nights of sleep, they were able to graph length of sleep against test performance, and come to some very specific results.

The magic numbers: 7 to 8 hours

Let's get to the numbers. Owen's research associate, Conor Wild, explained the results.

"We found that the optimum amount of sleep to keep your brain performing at its best was between seven to eight hours every single night. That corresponds to what doctors will tell you, you need to keep your body in tip top shape as well," Wild said. 

Most intriguingly, those who exceeded the maximum suggested sleep time "were equally, as impaired as those who slept too little," he added.

As for why, exactly, excess sleep was just as detrimental as too little sleep? That's a topic for further study, informed by the massive trove of data they've now collected.

"We have a lot more that we're going to do with this data," Owen continued, "because we collected a lot of other information ... that we even haven't managed to look at yet. There are lots of other factors, such as the effect of aging. Are there differences between men and women? How are people in different countries dealing with different amounts of sleep? These sorts of things."

Too much sleep LOL

I suspect for most of us, the idea of getting "too much sleep" is probably a dream. According to Gallup, the average for U.S. adults is about 6.8 hours per night, with 40 percent rarely getting more than six hours.

Earlier this year, I wrote about an extensive U.S. military study that revealed just how little sleep U.S. soldiers get--and also prescribed what to do when you're trying to get by on far too little. (Short version: Drink a lot of caffeine on a specific schedule.)

But that's part of the price that entrepreneurs and leaders often pay. As my colleague Jessica Stillman writes, if you have five priorities--work, sleep, family, fitness, friends--you get to pick three. For many of us, sleep is one of the ones that suffers.

Speaking of which: Tomorrow's another day--and it will be here in about six hours.