Sleep yourself younger with twin doctors Xand and Chris van Tulleken

Sleep yourself younger with TV twin doctors Xand and Chris van Tulleken’s expert anti-ageing plan

  • Good quality sleep is critical to every aspect of your mental and physical health
  • That’s why getting enough of it each night is key to you living well for longer 
  • TV’s twin doctors Xand and Chris van Tulleken on how to sleep yourself younger 

Good quality sleep, night after night, is critical to virtually every aspect of your mental and physical health.

That’s why getting enough of it is key to feeling and looking younger, and living well for longer.

The evidence from the science for how lack of sleep can put strain on our bodies and age us is alarming. One night of poor sleep can undermine your immune system, while chronic poor sleep increases your risk of type 2 diabetes and diseases including dementia and cancer.

More recently it’s been shown to shorten telomeres, the protective ‘caps’ on the end of our strands of DNA which indicate biological age. Every time our cells divide, a bit of our telomeres vanishes. And when they’re gone, they’re gone. So the last thing we want to do is hasten our telomeres’ shortening by sleeping badly.

Good quality sleep, night after night, is critical to virtually every aspect of your mental and physical health, say TV’s twin doctors Alexander and Christoffer van Tulleken

Shortening of telomeres has been linked to heart disease, chronic stress, depression and obesity, all of which have a dreadful impact on your quality of life.

Sleep clearly matters for both our short-term and long-term health, which is why we consider sleeping better to be one of our four pillars of anti-ageing, and why today we’re going to show you how to improve your sleep.

We are terrified by the thought of not getting enough sleep. As junior doctors we worked epic hours — Chris hallucinated with fatigue and fell asleep while talking to patients. He knows he is a terrible doctor between 3am and 4am.

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Xand spent a couple of years commuting between North America, where he had a job and a son, and the UK, where he was presenting television, amassing more than 50 transatlantic flights a year. He gained 4 stone and would fall asleep over dinner, in meetings and during filming.

But what can you do to improve your sleep, or at least improve how well you function when you’re not optimally rested?

As part of our new BBC2 series, The Twinstitute, we tried to find out. Using ourselves as guinea pigs, we called on 30 sets of identical twins, taking advantage of their matching DNA, to try memory tests, physical challenges and diet-based experiments to investigate a range of popular theories about health and wellbeing.

We’ve used these experiments and other research to put together the anti-ageing series that’s running in the Mail this week. On Saturday we focused on the brain and how to improve and protct your cognitive function. 

Today, we unpick the mysteries of sleep, showing how you can get maximum rest out of the time you spend in bed — so you can live well for longer.


The Sleep Council estimates that one third of Britons get only five to six hours of sleep a night, and 12 per cent of Britons sleep for less than five hours a night.

This falls short of official recommendations — U.S. charity the National Sleep Foundation believes adults should aim for seven to nine hours (seven to eight for the over-65s).

We ourselves average five to seven hours — not nearly enough to function well and avoid premature ageing. We typically fall asleep late and there’s never the opportunity for a lie-in, so exhaustion accumulates.

Paradoxically, Chris has found that having a young child has imposed a good sleep routine. For many it can affect sleep horribly — no wonder people say having a child ages you.

Life is impossible if you have a lot of 5am starts and you’re going to bed at midnight, so Chris and his wife have worked on a decent evening routine.

The screens aren’t always off by 9pm, but life is more bearable with lights out by 11 — even if their 18-month-old daughter does get them up in the night.

Lifespan? No, think healthspan 

There is nothing more ageing than illness — and some might ask, what’s the point of living longer if the quality of those years is poor?

While life expectancy is 82.9 years for women, and 79.2 for men, many people only remain healthy up to 65, according to Age UK. After that, our risk of heart disease, dementia, stroke and cancer rises, leaving millions facing spending the last 15 years of their lives crippled by ill health. 

That’s why, increasingly, experts are focusing on ‘healthspan’: the number of years lived in good health. The idea is to extend those healthy years.

Scientists are looking into the processes that govern age-related decline and our risk of diseases, and many say a healthy relationship with sleep is one of the key ways of lengthening both your healthspan and your life…

We all know how grim it can be to function after a bad night — but the harm of even one night’s poor sleep was graphically illustrated by one of our experiments for The Twinstitute.

We separated two sets of identical twins into two camps and made our twin guinea pigs stay awake for 30 hours.

As they forced themselves to stay awake, our twin testers noticed a shocking drop in their reaction times and judgement — as if their brains had ‘aged’.

To see if there are any tricks to protect you from a bad night’s sleep, before the experiment one team of twins ‘banked’ an extra four hours of sleep by going to bed an hour early for four nights; the other team were allowed 12 20-minute naps during the experiment to see if the snoozes could refresh them.

We thought the power nappers would be at an advantage, as power napping has been shown to be effective in lots of studies.

To test their risk assessment, we asked our two pairs of twins to blow up balloons to the point just before they would burst. Then reaction times were measured by how quickly they responded to a light flashing on a board.

After 30 hours of sleep deprivation, the nappers were the worst affected — the balloon bursting rate rose to 24 per cent but the sleep bankers burst only 10 per cent of their balloons.

The reaction times of the sleep bankers didn’t really change but the nappers’ reaction times dropped significantly.

As a final test, we asked both sets of twins to try to land a 747 jumbo jet in a simulated cockpit. It requires risk management, co-ordination, memory and nerve, which are all compromised by a lack of sleep, and which tend to deteriorate as we age.

Everyone struggled with confusion and disorientation, but two planes were successfully landed — both by the twins who had done the sleep banking.

Scans back these findings up, with studies showing that sleeplessness appears to inhibit the frontal lobe of the brain, which causes the sleep deprived to make poor decisions.

This ties in with research showing that sleep is when your brain clears out toxins (including the ‘plaques’ which can be a hallmark of Alzheimer’s), negative thoughts and any trivial details you no longer need — clearing out the garbage and allowing the brain to rejuvenate.


Poor performance due to lack of sleep has been shown to be like being drunk.

A 2017 study from Tel Aviv University in Israel showed that brain cells — or neurons — deprived of sleep respond slower and send weaker signals than rested neurons. This might be why fatigue feels like being under the influence of alcohol — with the same memory and concentration lapses.

And it is why driving (or landing a 747) is so dangerous when tired. It actually takes longer for the exhausted brain to see things — messages from eyes to brain to muscles slow down.

Sleep is also when the brain undergoes repairs: short-term memories are converted to long-term memories, thought processes are organised, and new brain connections are built, restoring it.

Large studies have shown that poor sleep, over time, can even lead to brain shrinkage. The theory is that when you are sleep-deprived, the brain’s waste clearance cells prune the very cells they should be trying to preserve, ageing the brain rapidly.


Lack of sleep certainly leaves you vulnerable to cravings, which can lead to over-eating and weight gain, taking years off your life. 

During the day, Chris says he can resist the snack machine without too much effort. At night, when he’s tired, it’s another story. Pizza and sweets become the staple.

Lack of sleep certainly leaves you vulnerable to cravings, which can lead to over-eating and weight gain, taking years off your life

It’s not clear why this happens. It’s probably partly because the effort of resisting temptation becomes too much, but there are hormonal changes accompanying sleep deprivation that seem to drive consumption of high-calorie foods and can even induce a temporary state like type 2 diabetes.

This might explain why people who don’t sleep enough are more likely to develop type 2 diabetes, which is linked to dementia and cognitive decline, reducing your ‘health span’.

The chemicals released during sleep calm inflammation and bolster immunity. Studies have shown that better sleep can lead to fewer colds and immune-related disorders, and even a lower risk of cancer.

So getting closer to eight hours of sleep a night can make a dramatic difference to our health, how our brains age and how well we can use them as we get older.

Yet how many of us let bedtime slip by an hour to watch just one more episode of that box set, have another drink, or do a little more work, thinking it won’t make a difference? Well, now there’s good evidence that it certainly does.

  • The Twinstitute is on BBC2 on Wednesdays at 8.30pm.

Twelve steps to a good night’s sleep

Most sleep experts recommend sticking to the same sleep schedule — even at the weekend (that means no lie-ins).

Changes to a routine affect our body clock, causing what Till Roenneberg, a professor of chronobiology at the Institute of Medical Psychology at Ludwig-Maximilian University in Munich, Germany, has dubbed ‘social jet lag’ — it’s like travelling across time zones over the week.

When the Medical Research Council scrutinised the sleep habits and health of more than 800 men and women, they found that those who were ‘socially jet-lagged’ (meaning they kept different hours during the week to the weekends) were more likely to be obese — which is not good for your long-term health.

Most sleep experts recommend sticking to the same sleep schedule — even at the weekend (file photo)

One theory is that the change in schedule affects appetite hormones or how our bodies process fat and sugar.

Try this calculation to work out if you have social jet lag:

  • Take the mid-point of your sleep during a normal work night. For example, if you sleep from 10pm to 6am on workdays, the midpoint is 2am.
  • Compare this to your midpoint on weekends and days off. A sleep pattern of 1am to 11am at the weekend gives a midpoint of 6am.
  • The difference in the two times is your social jet lag. Experts believe a difference of two hours could be enough to cause health problems.

It’s not just social jet lag that conspires to wreck our sleep. As we age, when sleep arguably becomes ever more important, we can struggle to get enough of it.

Did you know… 

Regular exercise makes it easier to fall asleep and contributes to sounder sleep – but exercising sporadically or before bed makes falling asleep harder, says the National Sleep Foundation in the US. 

Studies show that between 50 and 70 per cent of elderly people struggle to get the restorative sleep their brains need. Our brains use cues from exposure to natural light to switch on — and then switch off — the body’s production of the sleep hormone melatonin.

One theory is that our ability to ‘take in’ daylight (via the light-sensitive cells at the back of the eye) declines as we get older. After the age of 60, as much as 40 per cent of daylight is not absorbed, impairing the body clock that tells us when to feel sleepy and wake up.


Chris has made it a mission to sleep better — having a young child helps, he says. After all, if he and his wife were giving their daughter a regular routine why wouldn’t they do the same thing for themselves? Weekend lie-ins are largely impossible, but he tries to be in bed by 10.30 pm and lights out at 11pm.

Reducing alcohol intake is important with this — he only drinks socially and unless it is a special occasion he’s still out for the count by 11.30pm on weekends. Here are his tips to better sleep:

Are you getting enough sleep? 

How do you know if you’re getting enough sleep — or that it’s good quality sleep?

The checklist has been devised for the National Sleep Foundation in the U.S. by a panel of 18 experts, including sleep doctors, neuroscientists and psychiatrists, who read and voted on 277 studies on sleep quality. 

To check the quality of your nightly sleep, answer ‘Yes’ or ‘No’ to the following questions:

  • Do you drift off to sleep within half an hour of going to bed?
  • Do you stay asleep all night or wake up only once (or twice for the over-65s)?
  • If you do wake up, are you asleep again within 20 minutes (or 30 minutes for the over-65s)?
  • Is at least 85 per cent of your time in bed spent sleeping?

The more ‘Yes’ answers you give, the better your sleep quality is. Four ‘Nos’ and you could be in trouble.

Are you getting enough sleep? A checklist has been devised for the National Sleep Foundation in the U.S. by a panel of 18 experts


If you feel tired and sleepy every morning, regardless of how much sleep you had the previous night, you could be suffering from a sleep disorder.

The following quiz, which was devised by Dr Daniel Buysse, a professor of psychiatry and chair of sleep medicine at the University of Pittsburgh, U.S., could help you identify if you need to see your GP about your sleep.

How to score: Rarely/Never (0); Sometimes (1); Usually/Always (2)

1. SATISFACTION: Are you satisfied with your sleep?

2. ALERTNESS: Do you stay awake all day without dozing? 

3. TIMING: Are you asleep between 2am and 4am?

4. EFFICIENCY: Do you spend less than 30 minutes awake at night? (This includes the time it takes to fall asleep and awakenings from sleep).

5. DURATION: Do you sleep between six and eight hours per day?




A low score could indicate a sleep disorder, which you should discuss with your GP. 

Does a nap really work?

Power napping has been shown to be effective in lots of studies, boosting memory and performance compared to no sleep at all.

A review published in 2006 in the journal Current Opinion in Pulmonary Medicine reported that a nap of less than 30 minutes promotes wakefulness and enhances performance and learning ability.

However, frequent long naps may be associated with higher morbidity and mortality, especially among the elderly.

Not all naps are equal and how you benefit depends probably on the individual, as well as how and why you take a nap.

Even for well-rested individuals, naps may have mood, alertness, and cognitive performance benefits. There are so many variables with napping (such as timing, duration, prior sleep, and regularity), that studies are very variable — but there are plenty that show benefits for shorter power naps in terms of vigilance, addition, logical reasoning, and alertness.

One study compared the effects of a nap with caffeine, and found the nap had greater and longer-lasting benefits.

The afternoon dip in alertness falls between 3pm and 5pm, so this is probably the best time to nap. Many studies describe 7pm to 9pm as the forbidden zone. Naps here will disrupt night-time sleep, so don’t fall asleep in front of the TV after dinner.

Keeping it brief seems to be key: ten to 20 minutes gives immediate benefit; 30 minutes takes a while to wake up from; any longer than 30 minutes and you might start to interfere with night-time sleep.

How alcohol wrecks sleep 

Using alcohol to help you get to sleep is not a good idea.

You might drop off more easily, because alcohol is a sedative which triggers an increase in the production of the sleep-inducing chemical adenosine in the brain, allowing a fast onset of sleep.

But alcohol can also trigger a dramatic clash of brain patterns during the night that means your sleep won’t leave you refreshed.

In studies, scans have shown that the brain appears initially to enjoy more ‘delta wave activity’ (when memories are firmed up, and brain cells are replenished) than normal.

Using alcohol to help you get to sleep could trigger a dramatic clash of brain patterns during the night that means your rest won’t leave you refreshed

But as the night goes on, the alcohol appears to trigger opposing ‘alpha wave activity’, which normally only occurs when the brain is awake but resting.

The alpha functions appear to offset the restorative efforts of the delta waves, causing a clash that can disturb your sleep and leave you feeling tired the next day.

Clashing brain patterns like this are normally only seen among people with chronic pain conditions or subjects given periodic electric shocks while they sleep during lab-based studies.

It takes the body roughly one hour to metabolise each unit of alcohol, so daytime or early evening drinking isn’t so bad, but heavy drinking, or a few drinks before bed, could cause problems.

A few drinks is also enough to aggravate snoring because it causes your body to relax, including the muscles of your throat. This can stop air flowing smoothly, and makes the tissues more likely to vibrate — loudly.

This also puts you at risk of sleep apnoea, where your airway droops in the night, temporarily shutting off your oxygen supply.

Your sleep is also likely to be disturbed by frequent night-time trips to the loo. Normally when we sleep, our bodies shut down messages to and from the bladder, putting it into hibernation.

Your brain usually soothes itself but alcohol disrupts this process, reducing the effects of the brain’s self-soothing chemicals.

And when the booze wears off the brain is left excited. You’ll feel anxious and sweaty — all hangovers are at some level a micro-withdrawal. If this happens in the middle of the night it will hugely disrupt sleep.

Nodding off in the day? Why coffee and sugar can make you feel worse

When you’re feeling tired, it’s tempting to use a stimulant to pep you up. But as we’ve found from experiments for The Twinstitute and previous series, this isn’t always the solution.


We spend £2 billion a year on energy drinks, typically seeking an instant boost of energy and focus. But do they work?

We spend £2 billion a year on energy drinks, typically seeking an instant boost of energy and focus. But do they work?

As an experiment for The Twinstitute, Chris approximated the contents of popular drinks by whizzing up his own concoction in a blender. He used 16 teaspoons of sugar to mimic the amount in many cans of energy drink, tipping in a double espresso and some vitamin B12, potassium and amino acids, which manufacturers claim help alertness.

To see if the drink could boost his brain power, Chris downed a large glass then underwent a gruelling air traffic control simulation. ‘The drink did seem to help me focus and concentrate and I noticed the caffeine increased my alertness,’ he says, ‘But 20 minutes into the test the sugar spike started to drop off.’

He got every plane down safely but was very glad it was just a simulation. ‘I’d consumed twice the recommended daily amount of sugar for a one day in the space of a few minutes and my body was struggling to handle it,’ says Chris.

VERDICT: ‘The caffeine probably helped but the sugar could have negatively impacted my performance — I’d have been better off grabbing a coffee,’ says Chris. In other words, don’t bother.


Most of us rely on caffeine in the form of coffee or tea to prop us up in the morning, but are we addicted to a drug that could be ruining our sleep? And does it actually improve your brain function, as many people think?

Like many people, Chris starts his day with coffee — in his case a pint of weak black instant. It gets him up and functioning (partly because it’s so disgusting — it also helps you empty your bowel).

Coffee has this effect because of its action on a chemical called adenosine, which builds up in our bodies as we are awake. Higher levels make us feel sleepy — like our body’s timer to tell us to prepare for sleep. Caffeine binds to adenosine receptors in the brain and stops the sleepiness signal getting through.

Most of us rely on caffeine in the form of coffee or tea to prop us up in the morning, but are we addicted to a drug that could be ruining our sleep?

Coffee can be great for other reasons: it is rich in compounds called polyphenols (found in many fruits and vegetables). These reduce blood pressure, cutting the risk of heart attack or stroke, and increase blood supply to the brain, possibly protecting against dementia.

In the BBC2 series Trust Me, I’m A Doctor, Chris and the team set up an experiment comparing the impact of caffeine on coffee lovers and people who never touch the stuff. After abstaining from caffeine for 12 hours, the volunteers were tested to measure mental agility, concentration and dexterity. They were then given either a caffeinated drink or a non-caffeinated placebo and did the tests again.

The team expected caffeine to give all the volunteers superpowers.

What about electric shocks?

There’s increasing interest in using mild electric shocks to boost brain function.

The charge is thought to improve connectivity between regions of the brain. As an experiment for The Twinstitute, Xand wore a tDCS (transcranial Direct Current Stimulation) headband while attempting an air traffic control simulation.

He said it triggered a tingling sensation, like an insect crawling across his scalp — but the gadget had no discernable impact on his focus. In fact, the test results showed Xand’s scores were 3 per cent lower with the device.

In fact the regular caffeine drinkers performed worse than non-caffeine drinkers in the initial tests — their reaction times were slower, they were sleepier and less alert. That’s because they were suffering from caffeine withdrawal.

And the regular coffee drinkers who drank the non-caffeinated drink got even worse as their withdrawal deepened. Not surprisingly, the coffee drinkers given caffeine perked up — but the caffeine only returned their concentration back to normal levels. It did not give them the hike they might have expected.

Even non-caffeine drinkers didn’t see a dramatic performance increase after a coffee. It made them anxious and shaky.

That’s one problem with caffeine. It can increase levels of adrenaline, which causes an irregular heart beat and raises blood pressure. This stimulation could be bad for those with high blood pressure already.

Caffeine does not usually affect performance in learning and memory tasks. It does improve reaction time and, at low doses, may reduce anxiety. But at higher doses, it raises anxiety, nervousness and jitteriness.

There is some evidence that caffeine may prevent cognitive decline in healthy people but studies vary significantly.

If you’re a coffee drinker, the boost you might feel after a strong cup of coffee could just be the relief you feel as you release your body from caffeine withdrawal. It’s why many of us reach for caffeine first thing: we need it to bring us back up to our normal speed.

VERDICT: Although caffeine can keep you from falling asleep, it doesn’t make your brain work better, and you can quickly become dependent on it. Don’t drink more than a couple of cups of caffeinated coffee in an hour. Avoid drinking it after 2pm if you think it could be keeping you awake. Chris doesn’t drink any after 4pm.

Chewing gum vs classical music 

Several studies have suggested chewing gum can improve attention, memory and cognitive function

Can chewing gum or listening to classical music boost concentration?

We put this to the test, with Xand chewing gum and Chris listening to music, to see if they could help as we did arithmetic and reaction tests while being thrown about in dodgems and on a fairground ride.

Several studies have suggested chewing gum can improve attention, memory and cognitive function because the chewing action increases activity in areas of the brain responsible for language, memory and consciousness. 

Research also suggests classical music can help focus — a paper in the journal Nature showed a significant increase in IQ when listening to Mozart.

The studies for both have produced mixed results so we weren’t optimistic. But the results were staggering, as we doubled our test scores.

Whether either technique will help you revise for an exam or job interview is another matter. Much probably depends on the background distraction: at a fairground, classical music works well — but probably not as well as going home…

Complied by Louise Atkinson

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