A study has found that getting too much sleep every night can actually be bad for you and reduce your cognitive abilities.

In June 2017, scientists from the University of Western Ontario conducted the world’s largest sleep study, with 44,000 people taking part in an online survey and various activities.

"We really wanted to capture the sleeping habits of people around the entire globe,” Adrian Owen, a co-author on the study, said in a statement.

Participants recorded how much sleep they’d had, and then answered an extensive questionnaire. One of the goals of the study, published in the journal SLEEP, was to see what impact different amounts of sleep had on the mind.

“We had a fairly extensive questionnaire and they told us things like which medications they were on, how old they were, where they were in the world, and what kind of education they'd received because these are all factors that might have contributed to some of the results," said Owen.

One surprising finding was that those who reported less than four hours sleep a night performed cognitive activities as if they were nine years older.

The team also found that how sleep affected the body was universal across all adults. Highest cognitive abilities were performed when someone had seven to eight hours sleep, regardless of their age.

Interestingly, they also found that getting too much sleep was just as bad as getting too little.

"We found that the optimum amount of sleep to keep your brain performing its best is 7 to 8 hours every night and that corresponds to what the doctors will tell you need to keep your body in tip-top shape, as well,” said Conor Wild, the study's lead author. 

“We also found that people that slept more than that amount were equally impaired as those who slept too little," added Wild, making tasks like setting a timer all the more difficult.

There have been various sleep studies done recently, with some suggestions that 8.5 hours is the optimum amount of sleep to get each night. Another study said that catching up on sleep on the weekend was a way to prevent your life expectancy decreasing from a lack of sleep.

This latest study gives us some more insight into how much sleep we really should be getting. And as doctors suggest, it’s probably best to avoid getting too much or too little.