More intelligent people tend be ‘night owls’ — they stay up later at night and wake later in the morning, research finds.
Children who stay up later at night are also more likely to grown up into more intelligent adults, the study found.
The results come from a survey of the sleep habits of 20,745 adolescent Americans.
The psychologists found that on a weekday the ‘very dull’ went to bed at an average of 11:41 pm and woke up at 7:20 am.
In contrast, the ‘very bright’ went to bed at 12:29 am and got up at 7:52 am.
At the weekend the differences were even more pronounced.
The study’s authors explain the average times people of different intelligences went to bed:
‘‘Very dull” individuals on average go to bed at 00:35; ‘‘dull” individuals go to bed at 01:03; ‘‘normal” individuals go to bed at 01:13; ‘‘bright” individuals go to bed at 01:25; and ‘‘very bright” individuals go to bed at 01:44.”
Remember that all these times are for adolescents, who tend to to sleep for longer.
The equivalent times for adults at the weekend would likely be earlier — especially as adults often do not have the luxury of sleeping in much at the weekend.
For an adult, going to bed after around 11pm and rising after 8am would constitute a more nocturnal person.
An evolutionary explanation
The explanation for this link between IQ and sleep patterns may go back into our evolutionary past.
Our ancestors generally woke earlier and went to bed earlier.
Dr Satoshi Kanazawa, the study’s co-author, thinks that staying up late is ‘evolutionary novel’.
So, staying up late is more modern and therefore more intelligent.
This explanation is highly debatable (see Dutton, 2013), but the link between IQ and sleeping later exists nevertheless.
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The study was published in the journal Personality and Individual Difference (Kanazawa & Perina, 2009).