Can our diet affect how well we sleep?

There are many solutions we might turn to in the bid for a better night’s sleep: a new mattress, changing our sleep routine, listening to soothing music, or practicing mindfulness to name but a few.

All of these can make a difference, but what about our diet? Are there any changes we can make to our eating habits that could help us get the sleep we need?

Senior Physiologist at AXA Health, Lauren Davenport, explains the relationship between what and when we eat and how well we sleep (and vice versa), and suggests which foods may help or hinder a good night’s rest.

The benefits of sleep

Many of us tend to overlook the importance of getting enough good quality sleep and the positive impact it has on our health and wellbeing.

In terms of our daily ‘To do’ list, it’s not even up there – sleep’s just something that happens once everything else is done. Yet the benefits include:

• reducing fatigue,
• boosting immunity,
• helping to maintain a healthy weight,
• boosting mental wellbeing end even helping to ward off some serious long term health conditions, such as type 2 diabetes and heart disease.¹

So it’s important to prioritise getting the sleep we need, in the same way we might getting our 5-a-day portions of fruit and veg, or meeting the guidelines for physical activity recommended to achieve better health.²

But what if you’re among the 25% of people in the UK reporting regularly sleeping less than the recommended 7-9 hours per night?³

Lauren says: “There’s no set menu for getting a good night’s sleep that will work for everyone, but research has suggested that there is an association between some dietary behaviours and better sleep.

You may have noticed before that some foods make you feel sleepy, while others give you a boost of energy. Post-Sunday roast sluggishness sound familiar? Or are you someone whose day only starts after their first cup of tea or coffee?”⁴

Read on to find out why that is, and how you can go about eating your way to a better night’s sleep.

Hormones

There are two main hormones responsible for sleep regulation: melatonin, which helps control our internal body clock, and serotonin, which is responsible for causing sensations like lethargy and drowsiness. Both can be impacted by what we eat.

Tryptophan is one of the building blocks of protein (an amino acid) and is a precursor to the sleep molecules melatonin and serotonin. Getting enough tryptophan in the diet, through protein-based foods such as:

• chicken and turkey,
• eggs,
• fish,
• and soybeans

can consequently help to induce sleep.

Carbohydrates also play an important part here. It’s the role of insulin (which is secreted when we eat carbohydrates), to open the gates for tryptophan to reach the brain where it can get to work.

It stands to reason that a lack of carbs may block this sleep-inducing process and why a combination of roast meat and potatoes can lure us into the land of nod.

When is the best time to eat in the evening?

Eating stimulates your body’s metabolism and blood flow to your digestive system.⁵ Scientific research on eating patterns and sleep duration suggests it’s best to avoid eating too late in the day, to allow time for the metabolic and digestive processes to slow down and give your body time to relax.

However, this isn’t the only reason. Establishing regular eating patterns and eating no less than three hours before you go to bed can help to improve sleep by optimising your body’s production of melatonin (the hormone that makes us feel sleepy) and controlling blood sugar levels.

It’s understandable that for some of us, eating three or more hours before bed may not be achievable, so don’t worry if you can’t. If you’re a shift worker or a busy parent, for example, it may be more helpful to focus on establishing a regular eating and sleeping regime and consider meal planning to help you stay on track.⁶

Which foods can enhance sleep?

Low GI (glycaemic index) carbohydrates: The glycaemic index is a rating system to determine how quickly carbohydrates can affect your blood sugar levels when eaten.

Opting for low GI foods (such as wholegrain pasta, bread, rice, oats and lentils) will help to keep blood sugar stable, as opposed to high GI foods that cause a spike in blood sugar levels and energy, and which, when eaten later in the day, may make it harder to go to sleep.

Water: Dehydration can result in a poor-quality sleep and feelings of lethargy the next day. Stay hydrated by drinking enough water throughout the day and keeping topped up with water-dense foods such as fruit, vegetables, and soups.

Don’t try to make up your fluid intake at the end of the day because the likelihood is your sleep will be disturbed by the need to go to the toilet during the night.

Minerals and vitamins: Certain minerals and vitamins might play an important role in our quality of sleep. Emerging evidence suggests that being deficient in magnesium⁷ could impair our sleep quality, so keeping levels topped up through our foods could play a part.

Including plenty of nuts, dark green leafy veggies, high fibre foods like beans and pulses, whole grains and looking out for certain fortified foods will help!

Melatonin: Because of its role in regulating the body clock, eating melatonin-rich foods may assist with sleep. Some foods high in melatonin content are nuts, mushrooms, legumes, eggs, fish, lentils and kidney.

Note that it takes some time for the melatonin to take effect, so aim to eat these foods a few hours before bed to feel the benefit.

Which foods can impair sleep?

High fat foods: A high fat intake, in particular saturated fat, may reduce your total sleep time as digestion is activated for longer, meaning increased time spent going to the toilet!

It can also increase feelings of tiredness throughout the day by interfering with our internal body clock, resulting in lower (REM) sleep efficiency, more awakening during the night and shorter and lighter sleep durations, according to some studies.

So, for better sleep, try to avoid eating a lot of fatty foods, such as chips, pastries, pizza, takeaways and fried food, instead enjoy them occasionally, as part of a balanced diet.⁸

Caffeine: Caffeine is a stimulant, which increases your state of alertness by blocking the sleep-inducing hormones in the brain and increasing the release of the stress hormone, Cortisol, which also helps wake us up.

Consuming caffeine close to bed time can have an impact on the time it takes to fall asleep, and decrease deep sleep, so both sleep quantity and quality are affected.

In fact, lack of sleep can create a vicious cycle because caffeine is a stimulant that many people use for a boost after waking up in the morning or to remain alert during the day.

Generally, the more tired you are, the more caffeine you’ll consume to stay awake during the day. A useful tip here is to introduce a caffeine curfew, whereby you cut out all caffeinated drinks after 2pm so that by bedtime your body should be caffeine-free.⁹

For more information, read our article on the Benefits of cutting down on caffeine 

Alcohol: Alcohol may appear to increase the ability to fall asleep, but it does have a negative influence on the quality and quantity of our sleep. The consumption of alcohol before sleep can increase the number of times we wake up during the night, affecting our quality of sleep. 

Sugar: Eating sugary foods, such as sweets, chocolate and fizzy drinks, can cause a spike in glucose and energy levels which isn’t ideal when trying to prepare the body for sleep.

Instead, swap out late night snacking for vegetable sticks, unsweetened popcorn or a few almonds and, as well as cutting your calorie intake for the day, you should find it easier to drift off.¹⁰

Spicy food: Spicy food can cause issues such as heartburn, indigestion and in some cases acid reflux, all of which can impair our sleep. These issues may be exacerbated by laying down, which makes it easier for acid to flow back from the stomach to the oesophagus, so it’s best not to eat them shortly before bed! 

Influence of sleep on food choices

As we’ve seen, there are plenty of ways that diet may influence the amount and quality of sleep we get, and it’s also true that how well you sleep may influence the food choices you make.

Sleep deprivation can affect our dietary behaviours, as those who sleep less are more likely to opt for high calorie foods to provide a necessary energy boost to face the day.

A lack of sleep can also be associated with choosing foods that have a higher number of calories from fats or refined carbohydrates, a lower consumption of fruits and vegetables, irregular eating patterns and more frequent snacking.

References

1. Sleep Deprivation - Sleep Foundation
2. Lack of sleep – YouGov
3. Sleep duration recommendations – National Sleep Foundation
4. Effects of diet on sleep quality – National Library of Medicine
5. Enhancing sleep through nutrition – My Sport Science
6. Effects of fat intake on sleep duration – Science Direct
7. Magnesium - NIH
8. Association between Fibre and saturated fat with poor sleep  - NIH
9. Caffeine and sleep – Sleep Foundation
10. Association between a low intake of vegetables, high intake of confectionary and poor sleep quality – NIH