Getting less than six hours’ sleep a night? Here’s what it does to your body

For once, a Hollywood beauty secret that doesn’t come with a whopping price tag. When asked how he stays looking so youthful at 53, the actor Paul Rudd replied it was down to a solid eight hours’ sleep a night, rather than any fancy lotions and potions. Still, for those leading stressful, busy lives, an extra hour in bed is a luxury; the average Briton gets six hours and 19 minutes’ sleep a night. 

Sleep has been marginalised by our 24/7 culture and many of our habits during the day aren’t supportive of healthy circadian rhythms – the body’s internal body clock. We are all so used to lack of sleep that we have normalised it, and think we can cope when we don’t have enough. 

The truth is that evidence is mounting that missing out on the sleep our bodies need can have significant effects on our health. Experts agree that the deterioration in looks and memory, and even an increase in the risk of cancer, can be mitigated by good sleep.

However, focusing on eight hours as the magic number would be a mistake. “There’s a huge difference between individual sleep needs, particularly as we age,” explains Dr Russell Foster, a professor of neuroscience and circadian rhythms at Oxford University and author of Life Time. 

In adults aged between 18 and 80 the span of healthy sleep can range between six and 11 hours. Anything outside of that is not recommended. “Focusing on getting eight hours can cause anxiety that actually prevents you sleeping,” agrees sleep therapist Dr Kat Lederle.

So if you’re after some of the rejuvenation treatment that Paul Rudd clearly enjoys, the first thing to do is work out what your individual sleep needs are and then defend them.

How do you know if you’re not getting enough? 

“It’s kind of obvious,” says Dr Foster. 

“If you don’t feel you’re performing optimally during the day; you need an alarm clock to drive you out of bed; if it takes a long time to wake up; if you are craving caffeine and sugar-rich drinks; you oversleep on free days – all of that is indicative you need more sleep. 

“A key way to unmask your true sleep needs is to see how long you naturally sleep for when you go on holiday.” Dr Foster says some of the short-term effects of not getting enough sleep include: “Doing stupid and unreflective things; being overly impulsive, less empathetic and more aggressive.” In the longer term there’s striking evidence that lack of sleep stores up health trouble for the future. 

Skin and appearance

Rudd may also have had a point about his youthful looks: “Tired people tend to have puffy faces and are less attractive,” says Dr Foster. “This is because there’s greater water retention in tired people who are stressed.”

The stress axis is key here. “We have evidence that stressed people age faster, and therefore if you don’t get to sleep you’re going to be stressed,” says Dr Foster. 

You might also simply dislike what you see in the mirror more, says Dr Lederle. “We know if you’re sleep deprived, your own perception of yourself is somewhat critical and warped. You look for the symptoms of tiredness and interpret them in a much more severe way.”

Brain Health

Not getting enough sleep means the body has less time to do growth and repair work overnight, which is key to all our cells, but has a huge impact on our brain health. 

“Disrupted sleep in the middle years predisposes one to dementia in the latter years,” says Dr Foster. “The data is striking. If you don’t get the sleep that you need then you impair the clearance of toxic substances, such as beta amyloid, which accumulate in the brain. Those misfolded proteins are believed to be causing dementia and Alzheimer’s.” 

In the shorter term, sleep is integral to memory consolidation. “Wonderful studies have shown that a night of sleep does help you actually solve a problem,” says Dr Foster. 

Cardiovascular disease

A risk of cardiovascular disease is linked to shortness of sleep. “It’s related to elevated blood pressure and, crucially, an inflammation of the inner lining of your blood vessels,” explains Dr Lederle.“The body hasn’t got a chance to rebuild your blood vessel walls, which naturally get damaged as we move around in the day.”

Immune system 

Studies have shown that if you’re sleep deprived prior to or immediately after having a vaccination, the efficacy of the vaccination drops. Where it might be 100 per cent effective for a rested person, it can be less than 70 per cent if you have less than six hours’ sleep a night. 

“A 30 per cent difference is quite considerable,” says Dr Foster. 

Cancer

Not getting enough sleep leads to higher levels of cortisol, which suppresses the immune system. “This means you are more vulnerable to long-term things like cancer, because those rogue cancer cells are getting past the immune system because it’s not working as effectively,” says Dr Foster. Night-shift workers are very vulnerable to cancer: “The WHO now classifies night-shift working as a probable carcinogen.”

Obesity

Studies have shown that the shorter the sleep duration, the greater the risk for type 2 diabetes and obesity. “It could be related to the stress axis, because when we are stressed we release cortisol and adrenaline, which throw glucose into the circulation,” says Dr Foster. 

Tiredness has also been linked to increased release of the hunger hormone ghrelin from the stomach and reduced release of leptin, which is the satiation hormone. “So tired people feel more hungry and are likely to consume more, especially high-sugar carbohydrates.”

Mental Health

Many types of mental illness are associated with sleep and circadian rhythm disruption. “Because sleep disruption has such a destabilising effect upon one’s moods, emotions and indeed one’s biology, it can exacerbate a mental-health condition,” says Dr Foster. 

Loneliness is also a consequence of lack of sleep. “Our desire to meet up with other people disappears when we are tired and we can become withdrawn,” says Dr Lederle. “We know that loneliness is a health risk and can take a physical toll.”

Another factor is a negative outlook. “We have clear data showing that if you have a tired brain you remember negative experiences but forget the positive ones,” says Dr Foster. 

The benefits of more sleep

As well as mitigating some of the long-term serious health risks, Dr Foster says that with more sleep: “You will feel better overall, more alert, and able to do what you’re asked to do with greater efficiency. People will find their ability to interact with others will be improved. It will impact your whole world view.”

Looking to improve your sleep? You may want to read our guides to the best mattresses (including mattresses for back pain), the best duvets and the best pillows (including pillows for side-sleepers and pillows for neck pain)