FAMOUS people love to boast about surviving on very little sleep. Politicians, entrepreneurs, artists, creatives and business leaders are notorious for it.
Winston Churchill, Margaret Thatcher and Ronald Reagan all claimed to exist on four hours of sleep a night. Tech leaders Marissa Mayer, Tim Cook and Jack Dorsey all swear by the four-hour sleep schedule and they're joined by people like Madonna, Bill Clinton, Leonardo da Vinci, Jay Leno and Thomas Edison. Our own former Prime Minister, Kevin Rudd, apparently gets by on three hours.
You might wonder, quite rightly, why we care how much shut-eye famous people get.
We often forage the daily schedules of people like these for secrets to their success - and a minimalistic sleep routine has this rather glamorous implication that these people can forgo what the rest of us need. Boasting about sleep deprivation amps up the idea that these people are invincible, remarkable, and unique. They are, just a little bit, superhuman.
There's one problem, though. Sleep scientists confirm virtually unanimously that we all need seven to nine hours of sleep a night.
Yes, it varies from person to person, but no expert is willing to back the four-hour-a-night regimen as healthy, desirable or sensible. In fact, one of the world's leading sleep scientists, Professor Matthew Walker, has just written in his new manifesto on sleep, Why We Sleep, that it is extremely dangerous to get anything less than six hours a night.
He says the number of people who can exist on four hours' sleep, rounded up to the nearest whole number, is zero.
In fact, having just six hours instead of the recommended eight can affect our heart health, lead to obesity, exacerbate mental illness, increase our chances of developing dementia and cause cancer.
"Insufficient sleep has been tied causally to obesity, cardiovascular disease and Alzheimer's disease," Professor Walker tells news.com.au on the phone.
"I think it's fascinating that you speak about Churchill who obviously suffered from cardiovascular issues and when we speak about Margaret Thatcher and Ronald Reagan - both of those were very vocal about their lack of sleep and the neglect of sleep.
"You can't tell anything from two people but I always have been curious and interested in the fact that both Reagan and Thatcher went on to develop Alzheimer's disease and we know that insufficient sleep across the lifespan is one of the most significant lifestyle factors that will determine whether you get Alzheimer's disease. So I think it may not be coincidental."
So actually, Madonna and the Silicon Valley insomniacs are endangering their health if they really are sleeping as little as they claim to be.
Anyone living on less than six hours is putting themselves in serious danger of deteriorating mental and physical health.
New research simply reinforces how vitally important it is to get the right quality and quantity of sleep each night. It encourages good heart health, better eating and exercise habits and better mental health, boosts our memory and confidence, restores our creativity and vitality, makes us more physically attractive and allows us to function better during the day.
It makes us safer drivers, more productive employees, more emotionally level partners and calmer parents.
And yet, even for those of us who are not running a country or a company, sleep can be elusive. Anyone doing shift work or nursing a newborn baby knows how life-changing it can be to get less sleep than you need.
We also live in a society that celebrates sleep deprivation, glorifies insomnia and judges the good sleepers among us as lazy. The very first, and perhaps most important, thing we can do to get better sleep is change our attitude to it.
Then, of course, there are the practicalities. According to Professor Walker, there are several simple changes we can make that will improve our chances at sleep.
We currently overheat our homes and we should actually be sleeping in a room that's set to about 18 degrees. We need to turn off our screens well before going to bed and make sure the bedroom is properly dark because darkness triggers the sleep hormone melatonin.
We should set regular times to go to bed and get up in the morning, giving ourselves roughly a nine-hour sleep opportunity window.
And we should really limit our alcohol and caffeine intake, preferably having our last coffee for the day at 2pm at the latest and where possible, avoiding alcohol in the evening altogether (it sedates us, which makes us think we get better sleep after a nightcap, but actually it's a false sort of sleep).
Beyond these little habitual and environmental changes, the reason we are all so chronically sleep-deprived is because we have allowed work to infiltrate our home lives.
We check emails on our phones, commute further and allow work responsibilities to eat into our mornings and evenings, literally reducing the amount of time we spend in bed. That's a little harder to adjust than the thermostat, but it could be a really important life change that enables us to get better, more restorative and longer sleep.
Anyone who could comfortably sleep past their alarm in the morning and anyone who feels like they can't function without caffeine before midday is technically sleep-deprived. If that's you - and it's definitely me - I would say it's time to seriously address the way you live your life.