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Everything we’ve ever been told about sleep has been a lie. Or, at least some of it.
First, we find out that hitting the snooze button repeatedly doesn’t have a negative effect cognitive ability, sleepiness or mood.
Now, a new study claims that we DON’T need 8 hours of sleep? What?!
At least that is what Anders Fjell and his research squad at the University of Oslo in Norway would have us believe.
“Short sleep is held to cause poorer brain health, but is short sleep associated with higher rates of brain structural decline?” the researchers asked in their paper published in the journal Nature Human Behavior.
“Adults are advised to sleep at least seven to eight hours each night and it is widely perceived that shorter sleep could be a pervasive negative factor for physical, mental and cognitive health, yielding increased risk of Alzheimer’s disease (AD) and other dementias,” they continue.
“However, we still do not know what amount of sleep is associated with good brain health and whether a causal relationship between variations in habitual sleep duration and brain health exists.”
As explained by New Scientist, what Fjell and his team did was conduct a series of studies using brain volume as a measure of brain health.
First, they looked at brain volume in relation to sleep duration at a single point in time, using existing data on about 47,000 people. Here, they found an inverted U-shaped curve, although the highest brain volume was linked with a surprisingly low 6.5 hours of sleep a night.
The team then carried out a further analysis that tracked about 4,000 people for up to 11 years. In this case, there was no correlation between sleep duration at the beginning of the study and brain shrinkage over this period.
They then looked at genetic data gathered in a study of about 30,000 people to see if “those who are genetically predisposed to have either short or long sleep durations have smaller brain volumes than more moderate sleepers.”
What they believe they learned was that failing to get enough zzz’s does not, in fact, shrink the brain.
That, of course, doesn’t mean you should now go around staying awake all night. Snoozing is still important.
“If you are feeling tired all day, then you probably sleep too little, and that can have negative consequences,” Fjell said. “But as long as you feel fine during the day, I wouldn’t worry about whether your sleep is 6, 7 or 8 hours.”
Michael Chee, head of the Sleep and Cognition Laboratory at the National University of Singapore, agrees.
“You should not lie in bed tossing and turning to meet [that] target,” he told New Scientist. “This study is quite reassuring.”