How Eating Sugar Before Bed Affects Your Sleep – The Alarming Truth

Eating Sugar Before Bed.
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Eating Sugar Before Bed

Sugar is a carbohydrate your body metabolises quickly, providing your cells with a quick energy source perfect as a pick-me-up. However, it also interrupts sleep when consumed too close to bedtime and in too great a quantity.

2016 study found that people with diets high in sugar have lower sleep quality and duration. A more recent 2022 study found a significant association between the consumption of added sugars and sleep quality.

The connection between sugar and sleep is simple: sugar increases restlessness and reduces sleep quality. It also makes falling and staying asleep more difficult, a particularly enlightening point for parents with giddy children.

The bottom line – eating sugar late at night overstimulates you, giving you energy. We recommend consuming sugar no more than three hours before bedtime so that your body can fully metabolise it and use the energy.


Why sugar is bad for sleep

When you consume sugar, your body metabolises it and turns it into energy, with the amount of energy proportional to the sugar consumed. Consuming more sugar extends the time it stays in your body up to several hours.

If you consume as little as a teaspoon of sugar up to an hour before bedtime, you will have an energy boost and stimulation while in bed.

It takes around an hour and a half for your body to burn through a teaspoon of sugar, so it is easy to see why sweets and chocolate keep you awake.

Eating Sugar Before Bed.


Sugar can disrupt your sleep in several ways, leading to a less restful night and potentially impacting your overall health. Here are some key reasons why:

Blood sugar fluctuations: Consuming sugar, especially processed foods and sugary drinks, can cause significant spikes and crashes in your blood sugar levels. This roller coaster effect disrupts your body’s natural processes and can lead to:

  • Hormonal imbalances: The fluctuations trigger the release of hormones like adrenaline, cortisol, and growth hormone, which can cause feelings of anxiety, restlessness, and hunger, making it difficult to fall asleep or stay asleep.
  • Energy crashes: The initial sugar high may make you feel drowsy, but as your blood sugar crashes, it can lead to a sudden drop in energy, waking you up in the night or leaving you feeling tired in the morning.

Inflammation: High sugar intake is linked to increased inflammation in the body. Chronic inflammation can disrupt sleep by impacting the nervous system and promoting the release of stress hormones that hinder sleep quality.

Gut health: Diets high in sugar can negatively affect the balance of good and bad bacteria in your gut. This imbalance has been linked to various health problems, including poor sleep quality.

Orexin levels: Research suggests that people who consume a lot of sugar tend to have lower levels of orexin, a chemical in the brain that promotes wakefulness. This deficiency can contribute to daytime fatigue but also make it harder to fall asleep at night.

It’s important to note that while research shows a connection between sugar intake and sleep quality, the exact mechanisms are still being studied. However, limiting your intake of added sugars, particularly close to bedtime, can be beneficial for promoting better sleep and overall health.


Beware of hidden sugars!

One of the biggest mistakes people make with sugar in their diet is ignoring the sugar content of savoury processed foods and sauces.

For example, there’s approximately 4.3g of sugar in 100g of red pasta sauce, equivalent to just less than one rounded teaspoon. While this is no danger a few hours before bedtime, it could keep you awake if eaten an hour before.

Sources of hidden sugar include:

  • Fermented and pickled foods
  • Sauces of all kinds
  • Yoghurt
  • Instant oatmeal
  • Salad dressing
  • Packaged fruits and vegetables

It’s easy to find the sugar content of most foods because there is a label that displays the sugar per a specified amount/quantity.

Anything ending in ‘ose’ (glucose, sucrose, fructose, lactose, maltose) is sugar, and honey, agave, and syrups are also sugars.


How much sugar is healthy for sleep?

There is a difference between natural sugars and added sugars. Natural sugars are found in healthy foods like apples, cucumbers, and yoghurt, while added sugars are found in processed foods, such as sauces, cereals, and pastries.

The World Health Organisation (WHO) and the UK’s nutrition advisers recommend that only 5% of your daily calorie intake should consist of added or ‘free’ sugars.

If your recommended daily calorie intake is 2,000, 100 calories should come from added sugars. That isn’t a lot when you consider a 20g serving of tomato ketchup has around 25 calories from added sugar.


How to cut down your added sugar intake

Try these tips to reduce your added sugar intake:

  • Reduce portion sizes.
  • Use natural sweeteners in tea, coffee, and other hot drinks.
  • Avoid fast food.
  • Eat whole instead of processed foods.
  • Switch to ‘low sugar’ sauces.
  • Eat dark chocolate instead of milk chocolate.
  • Eat plain cereals.
  • Drink diet soda.
  • Drink water instead of cordial.
  • Reach for fruit instead of processed snacks.
  • Weigh sweets and other loose treats to get the optimal portion size.  
Oatmeal is easy to prepare and can make you sleep well if you eat it before bed.
Pictured: Oatmeal is easy to prepare and can make you sleep well if you eat it before bed.

Reducing your added sugar intake isn’t tricky because natural sweeteners do the job, and plenty of sugar-free products taste delicious.

In addition to directly improving your sleep, lowering your added sugar intake can also help indirectly with weight loss and lower anxiety.

The truth is that your body does not need sugar to survive – it needs energy, and it is better to get this from slow carbs like whole-grain bread and pasta.

If you enjoyed this article, read our piece on the best foods for weight loss.   

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