Researchers who looked into the sleeping patterns of people with different chronotypes – ie, night owls and morning birds – found that no matter what your body’s natural preference is, getting to sleep before 1am seemed to be key for better ageing.
Another recent review of studies found that being out of alignment with our body clock could actually be leaving us more tired than not getting enough hours of kip, too.
So perhaps I shouldn’t have been as surprised as I was to learn from a study referenced in gut health company ZOE’s podcast that sleep duration might not be the most important factor for a long life.
Sleep regularity, rather than duration, might matter most
In the podcast, longevity enthusiast Bryan Johnson said that during one of the potentially life-lengthening trials he’s been involved in, “I was in bed at the same time, plus or minus one minute.”
We’ve written before at HuffPost UK about how sticking to a regular bedtime can help you kip better, even on weekends.
And it turns out that a 2024 paper listed sleep regularity as a “stronger predictor of mortality” than even sleep duration.
The scientists acknowledged that both way too much and way too little sleep are linked to an increased risk of premature death.
But after looking at four years of data from over half a million members of the UK Biobank, aged between 40-69, the researchers found that “higher sleep regularity was associated with a 20% - 48% lower risk of all-cause mortality”.
This was more strongly associated with mortality than how many hours of sleep participants got a night.
Additionally, the scientists “found that irregular sleep predicted [a] higher risk of mortality by cancer, whereas short sleep duration did not.”
Why might sleep regularity matter more than sleep duration?
This paper didn’t definitely prove that sleep irregularity causes premature death; it just found an association.
To find a causal relationship, you’d have to make some people sleep irregularly and others sleep on a more regular pattern, then observe when each group died (ethically, er, dubious, and why a lot of lifestyle studies are so difficult to run or prove).
Still, the researchers suggested that the link to both cancer and all-cause mortality “may be ultimately driven by circadian disruption,” rather than sleep deprivation.
It’s part of a series of studies that suggest our body clock, instead of just the length and quality of our kip, might be key to true rest and health.