A good night’s sleep could help boost your brain power – but only if you are a woman. And a long afternoon nap has the same effect on men, scientists have discovered.
Researchers from Germany discovered a link between women’s sleep and intelligence, and also found similar patterns for men who take afternoon naps. They believe the differences between how sleep affects the sexes could be down to how men and women’s brains are structured, as well as how hormonal changes affect the body during the day.
Scientists from the Max Planck Institute in Munich analysed the sleep patterns of 160 adults with a broad range of IQs, of which 72 were women and 88 were men.
Participants also underwent intelligence tests which measured reasoning and problem solving.
They monitored how sleep spindles – bursts of activity in the brain – appeared during the dreamless, non-rapid eye movement state of sleep.
Sleep spindles vary in length and intensity and can ‘light up’ different parts of the brain. They have previously been associated with intelligence.
The study, presented at the FENS Forum of Neuroscience in Copenhagen, found a link between slow sleep spindles and intelligence in women, but not men.
Professor Martin Dresler said the presence of sleep spindles could indicate the quality of white matter in the brain, which connects to grey matter – the information-processing parts of the brain.
He said that integrity of white matter was associated with higher IQ scores in women, but there was no such correlation in men.
This suggested the structure of women’s brains meant sleep which boosted this white matter could benefit their intelligence.
Researchers also examined 86 men having afternoon naps of 100 minutes – but no women were studied.
Men having naps showed the same link between slow sleep spindles and intelligence that was evident for women overnight.
The scientists said this showed there was a ‘fundamental difference’ between daytime and night-time sleeps.
They suggested the way hormones behaved differently during the day could cause the changes.
Professor Dresler said: ‘Our results demonstrate that the association between sleep spindles and intelligence is more complex than we have assumed until now.
‘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.’