Posted on 14 March 2023
The word longevity comes from the late Latin world longaevitas – long age. However, in the field of longevity science, we tend to stretch this definition a little. For us, longevity isn’t just about maximising our lifespan, but also the amount of time we spend in good health – our so-called healthspan. Most scientists working on slowing or reversing the ageing process will agree that extending human healthspan is the more immediate and pressing goal. Gaining 5 years of life expectancy is a small victory if those years are spent with a host of debilitating diseases that sap the enjoyment from life.
So, longevity is about widening the opportunity to enjoy our time as a conscious collection of atoms, which I should remind you (at the risk of further darkening the mood) is vanishingly brief in comparison to the age of life on Earth. But if that is the case, perhaps there is room to think even more loosely about how longevity could be achieved. After all, age-related disease and death are not the only things that limit our ability to experience what life has to offer. I would like to present to you the phenomenon called sleep.
The average person spends roughly 26 entire years of their life sleeping (or, as is the unfortunate case for many, trying to get to sleep). That’s about a third of your life that you are spending just lying in bed, unconscious, and not experiencing the joys of waking life. Now I know what you’re thinking: ‘Well what are we supposed to do about that? Isn’t sleep quite important?’ And of course you would be completely correct. Indeed, even a relatively small loss of sleep below the recommended 8 hours is associated with quite a substantial reduction in both healthspan and lifespan. At least, it is for most people. I would like to present to you the gene called DEC2.
DEC2 is a gene that helps to control the levels of a hormone called orexin. Orexin keeps you awake, and an insufficient amount of it causes the main form of narcolepsy (type 1 narcolepsy), in which the individual experiences brief losses of muscle tone. Yet some people have a rare mutation in DEC2 that causes them to produce more orexin than normal. These people sleep only around 5-6 hours a night compared to the average 8. Given the vital nature of sleep, you might think there would be some significant downsides, such as impaired memory and learning or increased risk of age-related disease. Yet bizarrely, these natural short-sleepers don’t seem to suffer any ill effects at all.
Yes, that’s right. If we genetically engineered the DEC2 mutation into the human genome using embryonic gene editing, humanity would gain 7 years or so of conscious life, and (at least as far as current evidence suggests) there would be no downsides whatsoever. It makes you wonder what other time we could be missing out on. Did you know that people spend about 1.5 years on the toilet during their lives? What if we excreted waste products through our skin like sharks? On second thoughts, maybe that one’s not such a good idea.
While this site is primarily focussed on the science of life and healthspan extension, we are interested in all technologies that significantly improve our opportunity to make the most of the time we have. Many people disagree about exactly what longevity means and the value of different ways of extending it. What if DEC2 mutations are found to shorten lifespan slightly, for example? Would you trade a year of lifespan for a year of wakefulness? The latter technically gives you more conscious time on this planet. This is the kind of question everyone has to answer for themselves, but we shouldn’t limit our options based on how we define the word ‘longevity’.
DEC2 modulates orexin expression and regulates sleep: https://doi.org/10.1073/pnas.1801693115
OurWorldInData - Time Use: https://ourworldindata.org/time-use
Title image by CHUTTERSNAP on Upslash
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