Although many of us blame alcohol for a bad night’s sleep, a diet high in processed carbohydrates and saturated fats has been shown to be detrimental to sleep quality, according to research published in the journal Obesity.
The link has been long suspected, with previous studies finding that people on high-fat and high-sugar diets are more likely to experience poor sleep than those who are not.
Researchers at Uppsala University in Sweden isolated the effect of diet on sleep by monitoring participants in a sleep laboratory while they followed both a healthy diet for a period of time and then one rich in processed food.
For functional nutritionist Pauline Cox, author of Hungry Woman: Eating for Good Health, Happiness + Hormones, this latest finding confirms what is understood about the impact of an “obesogenic diet” on our sleep.
Processed foods like pizza, takeaways, ready meals, biscuits, cakes and ice creams tend to be loaded with fats and sugars, which “upset our metabolism”, explains Cox. “Eating sugar late at night overstimulates you. Rising blood sugar prepares the body for activity. When we eat late at night, our body temperature rises. But when we are preparing to fall asleep, our body temperature falls, so eating late goes against our body’s natural desire to drop in temperature.”
From a sleep perspective, poor glycemic control can lead to a decrease in REM sleep, which plays an important role in dreaming and emotional processing.
High blood sugar may also cause headaches, increased thirst and tiredness, which can interfere with falling asleep.
“The other thing is that if we have lots of high GI [glycaemic index] foods in our diet, that can deplete our magnesium, which is our sleep mineral,” adds Cox.
So what are the foods we should and shouldn’t be having before hitting the sack?
Don’t: eat a slice of toast because you didn’t have time for dinner
While toast may appeal for ease and convenience, it could lead to a blood sugar spike, impacting your sleep and even your waistline.
“Due to working habits and busier lives, we tend to eat later in the day. It makes sense that we need simple, time-efficient options after a busy day,” says Cox. “But a slice of toast can have as much as 13-17g of carbs per slice, sending blood sugar sky-high. Add on the extra topping of jam or honey and you have a food that will see you slumped on the sofa in a carb coma, yet struggling to sleep when it comes to bedtime.”
However, there are ways we can still enjoy a quick and simple meal without sending our blood sugar soaring.
Do: swap toast and jam for eggs
Cox’s speedy meal go-to is a boiled egg or two, which she keeps ready prepared in the fridge. This quick and easy alternative to toast is packed with nutrients needed to support hormonal health, metabolic health and sleep.
“Eggs are such a super source of protein and mother nature’s multivitamin when it comes to nutrient density,” says Cox.
“Mix chopped eggs with some delicious olive oil mayonnaise, a sprinkle of chopped spring onion and put the mix on some seedy crackers. The combination of the healthy fats found in eggs, olive oil from the mayo, and seeds, along with the high protein content of the eggs, will help you feel fuller for longer and will have minimal impact on your blood sugars, therefore reducing sugar cravings, mood swings and supporting a good night’s sleep.”
Don’t: eat a creamy curry after the pub
A late-night chicken korma or tikka masala in a creamy sauce is a surefire way to raise blood sugars and fats before bed, says Cox, while anything too spicy will keep you awake by increasing digestive problems and further heating up your body. “The combo of rice, with its heavy carb load, and a rich, fatty sauce will see your glucose levels creeping up at a time when we want them to be nice and steady, just before bed.”
A few pints or glasses of wine from an evening at the pub will also send blood sugars sky-high and kick your kidneys into overdrive as they attempt to remove the excess. So, you’re almost guaranteed to be getting up to pee during the night. “The lack of deep, quality sleep will also worsen the hangover,” says Cox.
On the positive side, eating food after being at the pub will help to slow the release of alcohol into the body. Cox explains: “This means the liver has an easier job processing the alcohol, reducing that morning-after feeling.”
Do: opt for a tandoori chicken and salad if you find yourself ordering late
A protein-rich curry with plenty of fibre, such as a tandoori chicken and salad, or chicken curry sauce with added veges, will help slow the blood sugar spike. Have with a wholewheat chapati, which is lower in fat and higher in fibre than naan or paratha and won’t spike your blood sugar as much as white rice.
“If you want to be really angelic, you could accompany your curry with cauli-rice instead of regular rice. It really does taste better than it sounds,” says Cox. “You don’t have to pull out your food processor at 11pm at night; keep a handy bag of riced cauliflower in your cupboard [you can buy dried, dehydrated cauliflower rice], then just order the meat dish from your local takeaway and skip the side of rice.”
Gram for gram, cauliflower rice has a significantly lower glucose load than rice. Cauliflower rice has 2g of carbs per 100g (which the body breaks down into sugar) compared to white rice, which has 29g of carbs per 100g. Even our trusty brown rice has a 26g carb load per 100g. With 93 per cent lower carbs, cauli-rice could be the curry saviour.
Don’t: eat a salami pizza in front of the telly
We all love pizza, but the heavenly hit of carb-heavy base and cheesy deliciousness is the perfect combo for sending us into a carb coma. And it won’t do much for our waistline either. “In labs, when scientists want to help mice gain weight, the ideal way is to provide a meal high in both carbs and fat… and we aren’t much different,” says Cox.
Do: switch up your pizza by adding more veg
You can still have your pizza and eat it, with a few modifications. “There are many alternative, low-carb pizza bases you can buy ready-made, which you can use to reduce the blood sugar load of a pizza,” says Cox. “Loading up your base with veges such as peppers, red onion and mushrooms adds fibre, which will slow the blood sugar spike as well as helping you feel full before reaching for that last slice.”
Eating a side salad with your pizza can also reduce the impact of the blood sugar-boosting pizza. “A simple leafy side salad not only adds extra nutrients, but it will help keep the blood sugars down, which is good news for your waistline and sugar cravings,” says Cox.
Another simple way to minimise the impact of a surge of post-pizza blood sugars is to go for a walk after eating. “A stroll around the block will immediately help bring down your blood sugars, meaning a better night’s sleep and less sugar to get stored as fat as your hungry leg muscles mop up all that sugar from your bloodstream.” So, eat up, then lace up your trainers.
Don’t: snack on biscuits before bed
Sadly, there are very few pros to eating a biscuit before bed, says Cox. Often, we turn to foods out of boredom or even habit. “Our brain becomes entrained to produce hunger hormones at a time when we regularly eat. So, if you break out the biscuits at 10.30pm every night, you will find, just like Pavlov’s dog, we get a predictable hunger pang, even if you’re not truly in need of food.”
And your cravings might also be due to an imbalance in your diet. “Many of us don’t eat enough protein, which can leave us hungry, experiencing cravings,” says Cox. “These often are the brain seeking our amino acids and telling you it doesn’t have what it needs yet, so keep eating.”
Do: have a hot milk instead
A hot milky drink can feel really comforting before bed. Milk is rich in the sleep-inducing amino acid tryptophan as well as the sleep hormone melatonin, so it really can help you drop off. Cox recommends a warm cup of almond milk, which is also rich in tryptophan. You can also make up a delicious golden milk using turmeric, ginger and cinnamon.
Cox says, “There are plenty of pre-made mixes available, or you can steep a turmeric chai tea bag in some hot nut milk.”