Can lack of sleep make you fat? Do you really need eight hours? Ten sleep facts (and myths)

BBC research called society ‘arrogant’ for ignoring sleep and its many benefits. So just what does sleeping do for our health?

The older we get the harder it is to get a solid night’s sleep, due to biological changes associated with ageing that make sleep that much more difficult. But it’s hugely important not only because not getting enough shut-eye can lead to a lack of mental alertness the following day, but because of serious health issues such as heart disease, diabetes and depression that can result over the long term. 

A BBC survey last year even described society as “arrogant” for ignoring the benefits of sleep. But if you thought you knew everything about sleep, think again. Some common myths about sleep are based in fact, but others come from dreamland.

1. Lack of sleep can make you fat 

TRUE  Sleep deprivation makes you more likely to binge on sugary, salty and fatty foods. Several studies confirm the insomnia/junk food connection, with University of California Berkeley researchers suggesting that lack of sleep affects parts of the brain that control decision making.

A large-scale US study also found that women who sleep five or fewer hours a night are 15 per cent more likely to become obese than those sleeping for seven hours.

2. Older people need less sleep 

FALSE Arguably the most common misconception about sleep is you need less of it as you get older. Experts do agree that you may sleep more lightly and wake more frequently during the night when you’re in your fifties, sixities or older, and that may explain why you assume you need less sleep. But an adult’s need for sleep is the same at any age.

Of course, you could be more concerned by your teenage children’s desire for sleep. But don’t fret, it’s entirely natural for teenagers between 14 and 19 to crave more rest, with nine and a half hours suggested as the optimum.

This is because puberty can trigger a sleep phase delay in their normal circadian rhythms, and, while negotiating a bedtime with them might be tricky, a restriction on access to technology before bed has been proven to help.

3. You’re either a night owl or an early bird

FALSE Whether you’re a lark or an owl describes your chronotype. But according to chronobiologist Dr Richard Coleman, only ten per cent of us are extreme larks or owls, with everyone else falling somewhere between the two.

German researchers who scanned the brains of different chronotypes found a reduction in the integrity of white matter in owls, which might explain why they seem to suffer from permanent jet lag.

4. Essential oils help you to sleep

TRUE It may sound New Agey, but some studies claim aromatherapy oils really could help you sleep better. For example, Wesleyan University experts discovered that sniffing lavender before bedtime could increase the amount of time you spend in restorative slow-wave sleep (though the effect may be stronger in women than men). Chamomile, jasmine and vanilla oils have also been shown to help people drift off.

5. Power naps are good for you

TRUE/FALSE It’s true that a quick nap in the middle of the day can make you feel more refreshed and alert. But don’t nap for too long. According to the Medical School of the University of Massachusetts, a 20-minute nap can recharge your body, but half an hour may put you in a deep sleep, making you feel groggy afterwards. Napping during the day could also reduce your brain’s sleep drive later on, meaning you’ll struggle to nod off at night.

6. Exercise makes you sleep better

TRUE A Stanford University study suggests that middle-aged and older people who exercise regularly may fall asleep 15 minutes quicker and stay asleep for 45 minutes longer. So how much exercise should you do? According to the US-based National Sleep Association, 20 to 30 minutes of exercise a day. But don’t work out too close to bedtime, as it could keep you up longer.

7. Everyone needs eight hours

FALSE Eight is the magic number where sleep is concerned. But one person’s sleep requirements can vary from the next, and some can function normally and feel good on five or six hours, while others need nine or ten hours a night. However, experts say seven to eight hours is the right amount for most of us.

8. A comfy bed helps you to sleep longer

TRUE It may sound obvious, but the more comfortable your bed, the more you’ll sleep. A study by Dr Chris Idzikowski, director of the Sleep Assessment and Advisory Service, found that people whose bed is uncomfortable sleep for almost an hour less than those who love their mattress.

So how often should you replace your bed? According to the Furniture Industry Research Association, beds that are just six years old offer significantly less support and comfort compared with new beds.

9. There’s no such thing as too much sleep

FALSE If sleep is so good for you, then more must be even better, right? Not so, says mental health charity Mind. Sleeping longer than your body needs could cause health problems, with studies linking chronic oversleeping with heart disease, diabetes, depression, obesity, back pain and headaches.

10. Alcohol helps you sleep more deeply

FALSE Some people find that alcohol makes them drowsy, so logic suggests a tipple before bedtime could help you sleep better too. But the opposite is more likely, say Dr Idzikowski and the London Sleep Centre’s Irshaad Ebrahim. Their study suggests that while alcohol may help you to fall asleep faster, it also reduces rapid eye movement (REM) sleep, resulting in more disrupted sleep. Drinking may also lead to snoring and poorer breathing, neither of which help you feel refreshed.