Health & Wellness

Too Much Sleep Isn’t Good for Your Brain

A Canadian study has found shown that oversleeping is as bad for you as being sleep-deprived


By Katrina Caruso


Sleep is vital to your mental and physiological health, but how does it affect your ability to solve problems and communicate? To find out, neuroscientists at Western University in London, ON, in June 2017 launched what was billed as the world’s largest study of the relationship between sleep and cognitive function.

According to the results, published last month (September 2018) in the journal SLEEP, too little sleep results in impairment—reduced reasoning and verbal skills, as well as a reduced ability to store and recall information. And the same is true of too much sleep.

The researchers studied the performance of more than 15,000 participants who were put through a series of 12 cognitive tests. Those who slept more or less than the recommended seven to eight hours a night—about half the participants—saw their cognitive skills decline. Sleeping only four hours a night was found to have the same effect as aging eight years. Short-term memory was not found to be affected.

The effects of too little or too much sleep were the same regardless of a participant’s age, a result that researchers said suggests that the optimal amount of sleep is the same for all adults, no matter their age.

The researchers stipulated that the results apply only to those oversleeping or undersleeping on a regular basis—for example, sleeping five or 10 hours every night for a month.

The study also supported the idea that a good night’s sleep the night before a big exam or meeting will improve your performance: even among participants not regularly getting enough sleep, seven to eight hours the night before testing helped a person think better.

Photo: iStock/Motortion.