As I slump wearily over my living room table, clutching my third cup of coffee and feeling distinctly nauseous and fuzzy-headed due to the lack of sleep I am suffering from — I got “just” six-and-a-half-hours last night — I am pondering a particular breed of pest that my life seems to be filled with: the smug sleeper.

These are the people who seem to be able to survive — thrive, even — on precious little sleep; the people who don’t seem to find exhaustion an endlessly interesting and relatable conversation topic; people for whom mornings are apparently just as energising and joyful as any other part of the day (see also smug early risers).

I resent these people.

If they’re not making me feel bad for being so slothful, they’re tempting me into late-night escapades when I know I have to get up early the next day. Unlike them, I am guaranteed to wake up feeling hideous.

But alas, I know many such types.

There’s the colleague who writes witty newsletters every night at 2am, dozes off within “a couple of minutes”, sets his alarm for 8am and arrives in the office positively brimming with beans.

There’s the new-mother fashion CEO friend who’s never out of the pages of Vogue and has the most active social life I know, on four hours’ sleep a night, maximum.

And then there’s the Cambridge academic father of another friend who, during a meditation, asked God to grant him the miracle of needing less than the seven-to-eight hours of sleep he had been getting up until then.

He has leapt happily out of bed after six hours’ sleep ever since (true story).

I am not of this ilk. In an ideal world, I would be a nine-hours-a-night kind of gal, possibly even nine-and-a-half.

Come the weekend, if I am underslept, as I often am, I have been known to sleep in for teenagerish amounts of time (one recent and lovely slumber lasted over 12 hours).

Am I doing something wrong? Should I feel ashamed?

Should I, too, be asking for divine intervention, or at least be trying to train myself to sleep less?

As if to taunt me further, a new study on Tuesday (Oct 18) suggested five hours is the “tipping point for bad health”.

Was I to infer from this that I should therefore feel just fine on six or seven hours’ worth of sleep a night?

Thankfully, Russell Foster, professor of circadian neuroscience at Oxford university, tells me not.

He stresses that “there is huge individual variability in sleep” and that for some people, therefore, this tipping point could actually be six hours or seven, or more.

There’s no magic number for the amount of sleep we should be getting, Prof Foster says.

Instead, we should be figuring this out ourselves, based on whether or not we feel we’re firing on all cylinders.

An easy litmus test for this is whether or not we wake up before our alarm goes off in the morning — if we don’t, we’re probably underslept.

And not only does not getting enough sleep lead to poor physical health because of the increase in cortisol level it creates, which in turn suppresses the immune system; it also leads to bad mental health.

Prof Foster cites a 2006 study by a pair of Harvard researchers, for instance, who found that people who had not had enough sleep were more likely to hold on to negative memories and less likely to remember positive ones.

“Your worldview is being biased [by] negative experiences, which means you can end up making some quite seriously bad mistakes about how you run your life,” he says.

The scientific research on sleep can be confusing, though. And multiple studies have suggested that long sleep duration — more than seven or eight hours a night — is associated with higher mortality.

But just because sleeping a lot is “associated” with a higher death rate, that doesn’t make it sleep’s fault.

“We’ve got causal evidence that short sleep is bad for you — we don’t have causal evidence that long sleep is bad for you,” Matthew Walker, a neuroscience professor at the University of California, Berkeley, and author of Why We Sleep, tells me.

Prof Walker says evidence suggests the reason studies have made this link is that those who are sick tend to sleep more to compensate for this and that, furthermore, the quality of sleep — which is crucial — is not taken into account in these studies.

So yes, the smug sleepers might have some kind of strange, peppy social high ground, but they can keep it.

I don’t wish to train myself to need less sleep — those aren’t wasted hours as far as I’m concerned; quite the opposite. I want to savour sleep; luxuriate in it.

Because whatever Bon Jovi might say, if you’re gonna live while you’re alive then you can’t afford to put off sleep till you are dead. FINANCIAL TIMES

ABOUT THE AUTHOR:

Jemima Kelly is a columnist at the Financial Times, and she writes a weekly column on a range of subjects, from culture wars to crypto, as well as features, and sometimes hosts podcasts.