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  • Writer's pictureSophie Bostock, PhD

Eating for better sleep and mental health

Can what you eat have an impact on your sleep, and mood? Absolutely.

This is an active area for research and we don’t have all the answers yet, but in this article I highlight some key evidence that your diet, your mood and your sleep are closely tied together.

I’ll share some recommendations for the diet most likely to support good quality sleep, and emotional health.

Can changing to a healthier diet improve your mood?

Many studies have found that in the general population, people who eat diets rich in fruit and vegetables are less likely to suffer from depression. In the groundbreaking SMILES trial, researchers went one step further, and investigated whether changing diet alone could be an effective treatment for depression (Jacka et al 2017).

Volunteers were randomised to either a befriending intervention (where they had a social chat with a researcher once a week), or to meet a dietitian to receive advice about how to make improvements to their diet. They were recommended to follow a Mediterranean style diet made up of fresh fruits, vegetables, whole grains, legumes, nuts, extra virgin olive oil, and fish. For example, they might have agreed to increase their weekly fish consumption, or swap the occasional chocolate ice-cream for natural yoghurt with walnuts and a drizzle of honey.

After 3 months, 1 in 3 of those in the dietary intervention group were no longer depressed, compared with 1 in 12 in the befriending group.

Those who improved their diet the most experienced the greatest benefit to their depression.

Since the SMILES trial, a number of other studies have confirmed that a Mediterranean style diet can help to prevent the development of depression in vulnerable patients, and improve wellbeing in those with depression. Interestingly, when combinations of supplements are used (such as omega 3, vitamin D and folate), trial results are less consistent than with a whole food diet approach.

Can what you eat affect sleep quality?

Several large studies have found that people who eat a Mediterranean style diet are also more likely to have better quality sleep than those who eat diets richer in processed food and refined carbohydrates such as white bread, cakes and sugary drinks.

Too much sugar before bed, or foods which spike a rapid increase in blood sugar, are not helpful for sleep. Experiments in the lab, under controlled conditions, have found that evening meals containing more fats and sugar are followed by lighter more disrupted sleep, whereas meals richer in fibre and protein are associated with more time in deep sleep.

Big population studies have found that poor sleepers are also more likely to be lacking in various vitamins, such as vitamin D, Magnesium, and vitamins A, B, C and E. However, this doesn’t necessarily mean that if we take more of these things, it will improve our sleep. There is very little evidence that individual supplements can improve sleep, but this is an active area for research. It might be that poor sleepers are more likely to choose less nutrient dense diets.

We don’t fully understand why a Mediterranean style diet has such a broad range of benefits for both mood and sleep. A Mediterranean diet is rich in vitamins and minerals, reduces inflammation and has antioxidant effects. It also helps to fuel good bacteria in our gut that help to produce mood-boosting neurotransmitters. Sleep and mental health have a close relationship, so it could be that dietary-driven improvements in mood are also driving a secondary improvement in sleep.

Does how you sleep affect your diet?

We know that lack of sleep, or irregular sleep patterns, can influence our appetite hormones. Sleep deprivation sends our brain into survival mode. We are more likely to crave highly energy-dense, junk food when we’re tired. We produce more of the hormone grehlin, which makes us feel hungry, and less of the hormone leptin which makes us feel full.

To make things even more challenging, when we’re sleep deprived we have less self control, and we’re more likely to give into our cravings. Research suggests that we eat an extra 385 calories after a bad night’s sleep. That’s about 4 slices of bread, or a jam doughnut.

Having said all this, if you go to bed hungry, that can also interfere with your sleep.

If you’re hungry before bed choose a light snack of healthy, slow energy-release foods. Perhaps some wholewheat crackers, hummus, yogurt, a few nuts or berries.

So, to recap..

● A Mediterranean style diet has been linked to better sleep and mood - think fresh fruits, vegetables, whole grains, legumes, nuts, extra virgin olive oil, and fish.

● Too much sugar, or foods which spike a rapid increase in blood sugar, can cause problems for sleep. Meals with more protein and slow release fibre tend to be followed by better sleep.

This article was written for Bensons for Beds Sleep Hub and appears here.

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