During the war, Churchill got by on just four hours’ sleep a night, Margaret Thatcher famously needed only the same.

I don’t know about you, but I’m definitely more of an eight-hours-a-night girl. Well, I thought I was, until I had a baby this time last year and instantly began managing to get by on less.

If I get more than five hours in one stretch now I feel lucky, and yet I still worry that I’ll never ‘catch up’ on my lost sleep.

Interestingly though, scientists have now spotted a gene variant that means some people are programmed to cope on less than five hours sleep a night. By studying 100 sets of twins, researchers in Philadelphia found that those with the gene variant p.Tyr362His had fewer lapses of performance when deprived of sleep for 38 hours and recovered quicker afterwards.

[Read more: When the clocks go back: What to do with that extra hour]

This could be good news for those who worry they’re not getting enough sleep on a daily basis – perhaps you simply don’t need much.

Dr Nerina Ramlakhan, sleep expert for Silentnight says: “I’ve encountered many people who become anxious about their supposed sleep deprivation because they feel they might not be achieving the ‘normal’ amount of sleep. 

“Sleep requirements vary from person to person. For most of us, living in this age of information overload, the challenge is to achieve efficient deep sleep rather than a certain quota of hours. You’re more likely to feel rejuvenated if you’ve had five or six hours of efficient sleep than seven or eight hours of shallow, restless sleep.”

“Six to seven hours a night is normal,” adds social psychologist Dr Sandra Wheatley. “Most people will go to bed between 11 and 12 and wake up at 7. When people become mums and dads, they soon realise they don’t need that much sleep. When you have had that much sleep, you’ll be bouncing off the walls!”

So it seems how much sleep we need is a personal matter and there is no ‘optimum’ amount after all.

Now we’ve got that myth busted, let’s bust a few more…

“Each hour before midnight is worth two after”

“It depends on you, it’s not about midnight, there’s no magic number,” says Wheatley. “If you sleep when you feel tired, it’s going to do you more good. Having a quick nap in the middle of the day can be as good as having two more hours at night – and if you’re working shifts, midnight for you might be midday. So it’s more about trusting your body and what feels right.”

“20 minutes is the perfect-length power nap”

“Short naps of five to 15 minutes have been proven to be very effective at promoting energy renewal and increasing cognitive function,” says Ramlakhan. 

“Each of us has a sleep cycle, which goes in a wave pattern of lighter and deeper sleep,” adds Dr Wheatley. “To complete a full cycle, it’s 40 to 45 minutes for an adult and about half an hour for a baby. So with a 20-minute nap, you’re having enough of that wave to make you feel better, before it drags you into deeper sleep, which is harder to come out of.”

“Broken sleep is bad”

In 2012, experts showed that, historically, we woke up for a period during the night when we were quite sociable, before going back to sleep again, effectively having two sleeps. This idea died out in the 1920s, when we started believing eight continuous hours were best. Sleep psychologist Gregg Jacobs says: “For most of evolution we slept a certain way. Waking up during the night is part of normal human physiology.”