Dr Sara Gottfried is, in her own words, an “under-sleeper”. In our over-caffeinated, overworked and gadget-addicted society, she’s far from alone: researchers from Oxford, Cambridge, Harvard, Manchester and Surrey universities have found people are sleeping almost two hours a night less than they did in the ’60s – and our health is deteriorating as a result.
“We are a supremely arrogant species; we feel we can abandon four billion years of evolution and ignore the fact that we have evolved under a light-dark cycle,” says Oxford University’s Prof Russell Foster, who worked on the study.
“What we do as a species, perhaps uniquely, is override the clock. And long-term acting against the clock can lead to health problems. These include an increased risk of cancer, heart disease, type-2 diabetes and obesity.
“Under-sleeping is the next sugar scare – it’s a health time bomb,” says Dr Gottfried, adding that just about every aspect of modern living is stealing our sleep. “Our lives are more hectic than ever, more people live in cities where they’re less attuned to light-dark cycles, we binge-watch television shows, tablets emit sleep-disrupting blue light all evening, and it’s become normal for our bosses to email us at 9pm. What it means to be available has changed and our sleep is suffering.
“Screens aren’t the only culprits – eco-friendly fluorescent light bulbs and LED lights emit more blue light than old-school light bulbs.”
Gottfried says artificial light has a hugely disruptive effect on our body clocks. Linked to our circadian rhythm, which regulates cell regeneration, brain activity, hormone production and the regulation of glucose and insulin levels, our bodies naturally adjust to daylight and darkness.
To stay healthy, we should be sleeping like our ancestors by going to bed at sunset and waking at sunrise – a pattern all but dispensed with in the modern world. “If we deprived ourselves entirely of sleep, we wouldn’t live much longer than if we deprived ourselves of water, and five times quicker than if we stopped eating,” says sleep consultant Dr Neil Stanley.
“In over one million years of evolution, our sleep needs remain the same.”
So how much shut-eye do we actually require?
“The eight-hour thing is a myth,” says Stanley.
“Sleep needs are like height – different for everybody and down to genetics. Just like there are tall and short people, there are people who need four hours a night and others who need 11. You cannot train yourself to need less sleep and if you go without your required hours, you’ll do yourself harm.”
The way to tell if you are getting enough is simple, he says.
“If you feel awake and alert during the day, yes. If you feel sleepy in the day, no. And there’s a difference between feeling tired and feeling sleepy; the latter means literally wanting to sleep during the day.”
The ramifications of insufficient sleep are quickly felt: studies show that just one night without proper rest quadruples your risk of catching a cold. It suppresses immunity. You’ll have less motivation, less empathy, slower reaction times, poor concentration and increased appetite,” says Stanley.
Pennsylvania State University researchers found that less than six hours’ sleep a night causes levels of the hormone ghrelin, which signals hunger, to rise and levels of leptin, the sense of fullness hormone, to drop. When you’re tired, you’ll feel hungry, but never full.
“Long-term, regularly shaving an hour or more off your required sleep increases the risk of certain cancers, diabetes, Alzheimer’s, obesity, cognitive decline, depression and heart disease.”
A study from Harvard Medical School found that people who sleep less than five hours a night for five consecutive years have a 300% greater risk of hardened arteries.
“There is not one single good thing about poor sleep,” says Stanley, “yet we live in a society that at best disregards it and, at worst, views getting by on very little as a badge of honour.”
Gottfried says that while you may think you can get by on little sleep, the truth is only 3% of the population has the short-sleep gene (known as DEC2).
“I would stay up for 36 hours at a time during my medical training, surviving on coffee,” she says.
“But coffee – like anything else that delays sleep – is a high-interest loan and eventually your body will call that loan in.”
The brain is the organ most affected by poor sleep, says Gottfried. In the past 10 years, neuroscience has shown a lack of sleep can both change and age your brain.
Good sleep, however, “shampoos” your brain and washes away ageing toxins.
“During sleep, the space between brain cells expands 60% more than when you’re awake,” she says.
“This allows the brain to flush out built-up toxins with cerebral spinal fluid, the clear liquid surrounding the brain and spinal cord. It’s called the glymphatic system and this system works better when you’re sleeping on your side, rather than back or tummy.”
Then there’s ageing. According to research from the Harvard School of Public Health, sleeping five or fewer hours a night equates to ageing an extra four to five years.
“There’s a reason it’s called beauty sleep,” says Gottfried.
“From personal experience, it’s pretty dramatic how different my face looks when I’m tired. I look more pale and puffy.”
So can a Sunday morning lie-in repay the sleep debt of a tumultuous week?
“Yes, but it requires a mind-set change,” says Gottfried.
“In the past, I’ve racked up gigantic sleep debts and have gained weight, become stressed, and felt stiff and older than my years. Now I view sleep as a non-negotiable, and even though I have two children, a husband and a job, I no longer ‘steal’ from my sleep in order to fit everything in.”
She says little and often is key with repaying sleep debt rather than trying to catch up in one large chunk.
“Naps also help and a 20-minute daytime nap is the equivalent of an hour at night.”
Another tip is batch cooking: Every working person will know that cooking a fresh meal in the evening – and washing up afterwards – cuts into sleep. So now I soften my expectations and grab something quick, or I batch cook and eat heated leftovers. This small thing gives me an hour more sleep every night of the week.”
Clinical director of the Sleep School (thesleepschool.org), Dr Guy Meadows says: “A small sleep debt is easily repaid with an early night. But if you’ve raised children, travelled a lot for work, or suffered with insomnia, you’ll have a bigger sleep debt. Worse still, you may have become a bad sleeper, which makes the debt bigger.
“I tell the bad sleepers in my sleep clinic to stop chasing sleep, as this drives it further away. If you ask a great sleeper what they do to get to sleep, they’ll say ‘nothing’. If you ask a bad sleeper how they do it, they’ll give you a long list that includes warm baths and lavender pillow mist. My theory is that often the ways we try to chase or control our sleep is part of the problem. Try to be almost thoughtless about it.
“Sleep is the most naturally powerful performance enhancer known to humankind. It’s time we started treating it as such.” — The Daily Telegraph