How 20 minutes' extra sleep could help you say no to cake: Extra shuteye could reduce intake of unhealthy sugars by a third each day

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If you have a sweet tooth, it can be hard to resist just one last sugary treat in the evening.

But the key to stopping yourself snacking could be as simple as getting into bed.

A study found that an extra 20 minutes of sleep could help people cut back on the equivalent of half a slice of cake a day.

Sleep-deprived people who manage to spend more time in bed change to a healthier diet, according to researchers at King’s College London.

The findings were made after researchers wanted to know if an extra 90 minutes in bed could provide a health boost. 

Our collective lack of sleep has seemingly become a worrying norm, turning into a hot topic of discussion at school gates, office water-coolers and supper parties across the nation

They found that when a group of people who slept less than seven hours a night were helped to get an average of just 21 minutes extra shut-eye, they cut their intake of unhealthy ‘free’, or added, sugars by almost 10g – a third of their daily allowance.

The Fitbit 'fitness delusion'

Activity trackers are unlikely to make any difference, research suggests

Turning to wearable tech such as a Fitbit might convince us we’re getting in shape but users could end up taking even less exercise.

Unless strict targets are set – such as 10,000 steps a day – the activity trackers are unlikely to make any difference, a study found. In the trial, 322 people, who were not set any fitness goals, were assessed after six months wearing the bracelets, the British Journal of Sports Medicine reported. But while 57 per cent believed they had increased activity levels, their devices showed a ‘downward trend’ from the overall group average of 500 steps an hour.

Dr Luke Burchill, of Oregon Health and Science University which carried out the study, said: ‘To make trackers effective, users need to set a specific goal and stick with it.’ 

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This is the equivalent of half a slice of cake with icing, or three chocolate digestives. The group also cut down on carbohydrates. It is believed sleep deprivation makes brain cells react more strongly to unhealthy food, driving us to indulge in comfort eating. 

This may be why people who do not get enough sleep often put on weight. Previous studies have shown sleep deprivation can cause people to eat an extra 385 calories a day. 

Dr Wendy Hall, of King’s department of nutritional sciences, said: ‘The fact that extending sleep led to a reduction in intake of free sugars, by which we mean the sugars that are added to foods by manufacturers or in cooking at home as well as sugars in honey, syrups and fruit juice, suggests that a simple change in lifestyle may really help people to consume healthier diets.’

The study looked at 42 healthy people of normal weight who were slightly sleep-deprived, getting between five and less than seven hours of sleep a night. Half of these were given help to sleep longer, receiving four personalised tips such as avoiding caffeine, establishing a relaxing routine or not going to bed too full or hungry.

Results show 86 per cent of the group managed to increase time in bed by an average of 55 minutes, while half increased their sleep duration by an average 21 minutes. After a month of better sleeping, people cut their sugar intake by an average of 9.6 grams a day – around a third of the recommended daily allowance, or about half a chocolate bar.

Commenting on the results, published in the American Journal of Clinical Nutrition, the team said it may also be that people ate less sugar because they were in bed longer and had less time to snack.

They added that their findings suggest ‘increasing time in bed for an hour or so longer may lead to healthier food choices’.