A good night’s sleep can do wonders for women’s intelligence, whereas napping has a similar effect on men, a new study suggests.
Professor Martin Dresler and a team of researchers from the Max Planck Institute in Munich found that sleep boosts intelligence in women, but not in men.
Napping for 100 minutes in the afternoon was thought to have a similar effect on intelligence among men.
Researchers believe this might be down to differences in hormones at different times of the day.
Scientists recorded brain function by analysing participants’ sleep spindles – the electrical activity in the brain during the night.
Sleep spindles vary in length and intensity and occur in different regions of the brain.
Scientists have believed for some time that intelligence was linked to sleep spindles, however this is the largest study with a broad range of IQs to determine the association.
Professor Martin Dresler, from the Max Planck Institute in Munich, Germany, analysed the brain function of 160 adults – 72 women and 88 men – while they slept at night.
He found that men and women differed hugely in terms of brain function.
There was a positive correlation between intelligence and slow sleep spindles in women but not in men.
Professor Dresler believes sleep spindles indicates the integrity of white matter in the brain that connects the different regions of information-processing grey matter.
This, in turn, contributes to intelligence.
Speaking at Europe’s largest neuroscience conference in Copenhagen on 6 July, Professor Dresler said: “In line with our results, IQ scores correlate much higher with measures of white matter integrity in females compared to males.
“In other words, in females there is a more straightforward relationship between these neural structures and their function in intelligence compared to males, which can also be seen in the sleep EEG (a recording of brain activity).”
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While women were most likely to benefit from a good night’s sleep, napping was found to benefit men more.
In a study of 86 men having an afternoon nap of 100 minutes, Dr Dresler’s team found that there was a link between slow sleep spindles and intelligence – similar to the correlation seen for women during nighttime sleep.
The sleep data in men suggests a fundamental difference between night and daytime sleep, possibly because hormones behave differently according to whether it is night or day.
“Our results demonstrate that the association between sleep spindles and intelligence is more complex than we have assumed until now,” said Dr Dresler.
“There are many factors involved in intellectual abilities, and sleep is just one of them.
“This large study of men and women give us a more accurate framework for the next phase of research which will involve differences in individuals’ sleep patterns.”