Sleep – Key to Tackling Obesity

The focus in the fight to tackle obesity tends to be diet and exercise, but what role does sleep play and what are the effects of sleep disorders?

By Dr Neil Stanley

It is an undeniable fact that we have a problem with obesity in the UK. The government and the NHS rightly believe that for the health of the nation, levels of obesity need to be reduced. So we have campaigns based on eating less and more healthily, such as “5-a-day” and exercise – “10,000 steps a day” and the “Change for Life” initiative. However, given recent reports, these efforts, whilst very well-meaning, are seemingly having absolutely no effect on reducing levels of obesity or increasing rates of exercising.

The conventional line is that this is because we are all victims of the “aggressive advertising” and “easy availability” of sugary and fatty foods and/or that we are addicted to computer games/TV/Facebook etc. It is possibly true that in the past we did move a bit more than modern children, but I seem to remember that surgery and fatty foods were just as “aggressively” advertised and easily available.

My “bog-standard” comprehensive school had a tuck shop and there were plenty of local shops selling a myriad of sugary and fatty comestibles for our delectation.

Hunger hormones

Perhaps there is some other reason why the “eat less, move more” advice is not working. What if we simply cannot help ourselves? And that, from a physiological point of view, we actually crave junk food and don’t want to exercise?

So what might be the answer?

Numerous studies have shown a significant association between short sleep duration and being overweight or obese in both children and adults. And I believe that it is more than coincidence that, over the last 40 years, as there has been a reduction in our sleep duration, there has also been a rise is the number of people who are overweight or obese.

Using fMRI (functional magnetic resonance imaging), poor sleep has been shown to affect the brain areas responsible for complex decision-making and response to rewards causing us to favour unhealthy foods. Poor sleep also causes changes in the levels of our hunger hormones. There is a decrease in the level of leptin – which regulates food intake and signals when we have enough food, while the level of ghrelin – which stimulates appetite, fat production and body growth – rises.

Apple – or cupcake?

Research suggests this causes 24% higher feelings of hunger, a 23% increase in overall appetite but a 33% increased desire for high-fat, high-carbohydrate foods making us feel that we have had insufficient food and thus encouraging us to increase food intake.

Short sleep has also been shown to increase our urge to snack between meals and causes us to excessively season our food, eat fewer vegetables, buy more junk food and buy more food overall.

So the availability and advertising of junk food is seen as the problem.

However, the simple fact is that because of poor sleep, you may actually physiologically want to eat these foods regardless of the efforts of the multi-national purveyors of junk food – though this is in no way trying to absolve them of their responsibilities.

But be honest – when you are sleepy, which would you prefer: an apple or a cupcake?

The “eat less, move more” message, no matter how it is presented and how much money is spent on its promotion, is obviously not working – and I would contend that, in isolation, it cannot work. Up until now, there has been no serious government or NHS advice or guidance about sleep, no multi-million pound campaigns – they haven’t even appointed a scientist off the telly as a “Sleep Tsar”.

I believe that if we are serious about reducing the weight of the nation and increasing rates of exercise, we need to address the issue of poor sleep.

Isn’t it is time for a new approach – “eat less, move more, sleep well”?

Dr Neil Stanley

Sleep ‘boosts brain cell numbers’

Scientists believe they have discovered a new reason why we need to sleep – it replenishes a type of brain cell numbers.

Sleep ramps up the production of cells that go on to make an insulating material known as myelin which protects our brain’s circuitry.

The findings, so far in mice, could lead to insights about sleep’s role in brain repair and growth as well as the disease MS, says the Wisconsin team.

The work is in the Journal of Neuroscience.

Dr Chiara Cirelli and colleagues from the University of Wisconsin found that the production rate of the myelin making cells, immature oligodendrocytes, doubled as mice slept.

The increase was most marked during the type of sleep that is associated with dreaming – REM or rapid eye movement sleep – and was driven by genes.

In contrast, the genes involved in cell death and stress responses were turned on when the mice were forced to stay awake.

Precisely why we need to sleep has baffled scientists for centuries. It’s obvious that we need to sleep to feel rested and for our mind to function well – but the biological processes that go on as we slumber have only started to be uncovered relatively recently.

Growth and repair

Dr Cirelli said: “For a long time, sleep researchers focused on how the activity of nerve cells differs when animals are awake versus when they are asleep.

“Now it is clear that the way other supporting cells in the nervous system operate also changes significantly depending on whether the animal is asleep or awake.”

The researchers say their findings suggest that sleep loss might aggravate some symptoms of multiple sclerosis (MS), a disease that damages myelin.

In MS, the body’s immune system attacks and destroys the myelin coating of nerves in the brain and spinal cord.

Future studies could look at whether or not sleep affects the symptoms of MS, says Dr Cirelli.

Her team is also interested in testing whether lack of sleep, especially during adolescence, may have long-term consequences for the brain.

Sleep appears necessary for our nervous systems to work properly, says the US National Institute of Neurological Disorders and Stroke (NINDS).

Deep sleep coincides with the release of growth hormone in children and young adults. Many of the body’s cells also show increased production and reduced breakdown of proteins during deep sleep.

Since proteins are the building blocks needed for cell growth and for repair of damage from factors like stress and ultraviolet rays, deep sleep may truly be “beauty sleep”, says NINDS.


Why does sleep matter?

Experts acknowledge that sleep plays a significant role in brain development, and it is therefore important to get enough sleep.

As well as the role it plays in brain development, sleep also plays an important role in our brain’s day-to-day ability to function. Lack of sleep makes it much harder for us to concentrate, and we become forgetful, irritable and prone to being clumsy and making mistakes. Furthermore, scientific evidence shows that the right amount of nighttime sleep is just as important for children’s development as healthy eating and regular exercise.

A lack of sleep can contribute to weight gain too, because it inhibits the production of appetite-controlling hormones.

Sleep requirements differ from individual to individual, but in general a younger person needs more sleep than an older person.

If you find it difficult to get up in the morning and are tired and irritable during the day you may not be getting enough sleep. Experts have also linked a lack of sleep in children to problems with behaviour, concentration and achievement at school.

Tips for better sleep

Limit your use of the internet, games consoles and TV in the hour before you go to bed – and ideally don’t allow a computer, console or a TV set in the bedroom.

Here is a list of 10 tips for getting a better nights sleep which you may find useful.

Are you losing sleep?

Sometimes it can be hard to switch off when you’re stressed out – but don’t despair! There are things you can do to ensure a better night’s sleep…

Getting a good night’s sleep can be a real problem when you’re working hard. You close your eyes and your brain wakes up – and then you lie in bed awake for hours wishing you could fall asleep.

Ideally you should be getting between 7-8 hour sleep a night. Ideally teenagers should get 9 hours sleep but that won’t always be possible. Sleep is an essential part of our lives and is necessary for us to function well. If you want to be on top form in an exam then it’s essential you get a good night sleep.

Top tips for stress-free sleep

  • Stop your revision a good hour before you want to sleep – Your brain needs time to switch off and unwind.
  • Do some exercise; it’s a great way to reduce stress levels and tire you out to help sleep.
  • Don’t eat a heavy meal too close to going to bed or your body will not be able to relax, because it will still be digesting the food.
  • Avoid caffeinated drinks such as tea, coffee, or cola after 6pm.
  • Have a milky drink. It contains a chemical called tryptophan which is an essential component of the body’s sleep mechanism.
  • Sleep in complete darkness or as close to it as you can; that way there is less to distract your eyes.
  • Wear socks to bed. Due to the fact they have the poorest circulation in the body they can often feel cold when you go to bed.
  • Try counting sheep – it sounds boring, but that’s the whole point! Focusing your mind on a mundane task will stop you from worrying about your work.
  • If you really can’t get to sleep, don’t panic – it won’t help. Get up and do something monotonous like filing some notes or folding clothes.
  • If you can’t sleep the night before an exam, don’t worry. The odd night without sleep will not be devastating, because the adrenaline will see you through.

Why do we Sleep?

A recent study into why do we sleep may have an answer to one of the greatest unsolved mysteries in science – what is the purpose of sleep? The work suggests it’s actually about making animals function more efficiently in their environments.

Pythons, bats and giant armadillos are among the longest sleepers at over 18 hours a day. Human babies need 16 hours, and most of us probably feel we need around eight hours sleep to function well.

Professor Jerry Seigel from the University of California, Los Angeles, conducted a study of the sleep times of a broad range of animals and found that they vary widely. Some, like migrating birds, can survive long periods without sleeping at all. He believes that shows sleep evolved to conserve energy:

Jerry Seigel: ‘It’s animals that are needlessly active that will not survive, but animals that are most efficient and use their waking time to do vital functions, and are otherwise asleep that will survive.’

Sleep helps make best use of limited resources. In humans, when we’re awake, our brain accounts for 20% of the energy we use when just sitting around. Sleeping also makes us less likely to get injured and less likely to be detected by predators.

Five things that stop a good night’s sleep

Tossing, turning, can’t get to sleep? It’s a familiar feeling for many. Here are five things that could be preventing us from getting the restful night we need.

An uncomfortable or noisy environment

As we start to fall asleep, our muscle tone reduces and our limbs begin to relax. We may feel drowsy but our brain is still active, and any noise or discomfort can make it hard to fall asleep.

As we drift into light sleep, an area of the brain called the thalamus starts to block the flow of information from our senses to the rest of the brain. But it will still let through noises, which can wake us up.

After about half an hour of light sleep, most of us enter a type of deep sleep called slow-wave sleep. The changes in the brain neurochemistry typical of deep sleep, make it harder to be woken up. But some things will always get through – such as our names being called out loudly.

Missing out on any part of our usual cycle of sleep results in reduced quality and quantity of sleep.

An irregular routine

We all have a built-in body clock which tells us when we are tired, and helps synchronise thousands of cells in our body to the circadian rhythm.

The main synchroniser for our body clock is light. Our eyes react to the light and dark, even when our eyelids are closed.

Daylight prompts our brains to reduce the production of the sleep hormone melatonin. We become more alert, and wake up.

If we sleep less, because of going to bed late or waking up early, we’re unlikely to get as much deep sleep as we need, or enough of the stage that comes after it – REM (rapid eye movement) sleep, when we do most of our dreaming.

Stimulants – coffee, alcohol, food

Caffeine is a stimulant which can stay in our system for many hours. Drinks high in caffeine make it harder to fall asleep and can result in more time in the lighter stages of sleep, with less deep sleep.

Drinking alcohol often makes us snore more, making it harder to breathe, and so making us more restless.

Although alcohol initially helps some of us fall asleep, too much of it may disrupt sleep. A lot of alcohol close to bedtime means we can go straight into deep sleep, missing out on the usual first stage of sleep.

As the alcohol starts to wear off, our bodies come out of deep sleep and back into REM sleep, which is much easier to wake from.

In the course of a night we usually have six to seven cycles of REM sleep, which leaves us feeling refreshed. However, a night of drinking means we’ll typically have only one to two, and wake up feeling exhausted.

Eating a large, heavy meal too close to bedtime may also interfere with sleep. Spicy or fatty foods can cause heartburn, which leads to difficulty in falling asleep and discomfort throughout the night.

Foods containing a chemical called tyramine (examples include bacon, cheese, nuts and red wine) can keep us awake at night.

Tyramine causes the release of noradrenaline, a brain stimulant. Carbohydrates, such as bread or pasta, have the opposite effect. They trigger the release of hormone serotonin, which makes us sleepy.

The wrong body temperature

Our core body temperature goes down when we sleep. It’s controlled by our body clock, which starts to open up the blood vessels of the hands, face and feet, to lose heat, as we approach the time we should be sleeping.

But if our bedrooms or duvets are too warm, our bodies can’t lose heat. That can lead to restlessness and discomfort.

Our core temperature should only be half a degree less than during the day. If we get too cold, we get restless.

A busy mind

Stress is the enemy of sleep. In bed, our mind is left free to wander, and feeling anxious about getting enough sleep will only make it worse.

In these states people lose track of time. You may nod off and wake up again but it may still feel as if you are getting no sleep at all. This can result in fragmented sleep with less time spent in the deep stages of sleep.

Sleep experts recommend getting up and doing an activity which distracts our mind from worry – such as a puzzle – before trying to sleep again.