From Vegan to Intermittent Fasting, These 4 Diets Wreak Havoc on Your Sleep

We know what we eat has a huge impact on how we feel physically and mentally. But so often nutrition as a factor of good sleep is overlooked and undervalued.

To put it simply, our nutrition can significantly affect our sleep; how long it takes to fall asleep, stay asleep and the quality of our sleep. We eat and drink for enjoyment, but we also eat and drink for the fuel, vitamins and minerals required for our bodies to operate each day – which includes performing basic innate functions such as sleeping.

We won’t beat about the bush - there are a lot of diets floating around out there. You’ve likely heard about many of the more popular ones through friends or platforms such as Instagram, YouTube and Facebook. These diets (whatever their end goal) tend to encourage increased consumption of certain nutrients and decreased consumption of others, which can in turn negatively impact your sleep. Here are the four worst diets to avoid.

4 worst diets affecting your sleep

1. Ketogenic diet

Not entirely favoured amongst dietitians, the keto diet involves consuming a high amount of fat and an extremely low amount of carbohydrates.

Insomnia is just one of the very common side effects reported by those who follow this diet, particularly in the initial phases of transitioning to using fat as the major macronutrient to fuel the body. Research has demonstrated that a diet high in fat can decrease the amount of restorative sleep we get, and decrease sleep efficiency. Why? When we eat carbohydrates, it triggers our body to release insulin into our bloodstream. So, when we eat less carbohydrates, we release less insulin. One of the many roles of insulin is to help an amino acid known as L-tryptophan to enter our brain. L-tryptophan is involved in creating melatonin. For anyone who may not have heard of melatonin before, it’s a hormone that helps to regulate our sleep/wake cycles. To put it simply, less carbohydrates in the diet can have the eventual effect of decreased melatonin production. 

The keto diet also has the potential to trigger electrolyte imbalances, including low magnesium levels. Magnesium is a superstar at getting our nervous system to enter a calm and relaxed state that promotes sleep; people with low magnesium levels often wake up more frequently during the night. 

2. Paleo diet

Like old-mate Keto, the Paleo diet is also commonly low in carbohydrates – it restricts intake of grains and legumes. Overall, the Paleo diet is considered to be high protein. A study examining the effects of different diets on sleep found that higher protein intake increased a participant’s chances of experiencing difficulties staying asleep throughout the night. In comparison to a high protein diet, it appears that people who do not restrict carbohydrate intake may fall asleep more quickly. Again, due to low carbohydrate quantity, L-tryptophan is less able to enter the brain and produce melatonin. 

Another finding regarding low carbohydrate diets such as the Paleo diet, is that there is often a reduction in the production of serotonin - a brain chemical that helps with sleep regulation as well as improved mood and feelings of wellbeing. Low serotonin can make us feel stressed and anxious, with cortisol levels rising as a result, and yep, you guessed it, increased likelihood of sleep issues. 

3. Intermittent fasting 

Intermittent fasting (IF) is sort of an umbrella term for different methods of scheduling your eating with intentional periods of little or no food intake. Some types of IF encourage you to eat all your meals within a specific window of time (for example, eating all meals within eight hours of waking, and not eating during the other 16 hours of a 24-hour period), or not eating breakfast and fasting until later in the day, or the 5:2 method of restricting calorie intake drastically on two out of seven days per week. 

Why does IF impact many people’s sleep? Fasting for long periods of time can increase the amount of stress hormones in our body. This then encourages heightened sensations of unease - and who sleeps well when they’re feeling anxious? Research shows that including a nutritious wholegrain source of carbohydrates in your evening meal (approximately 3-4 hours before bed time) can produce better quality sleep. We also can’t forget the research that shows any predisposition to insomnia can be worsened on an empty stomach, so pass the brown rice, please! 

4. Veganism 

People may choose to be vegan for a myriad of reasons. The observation that sleep quality may decrease with a vegan diet is more often due to the fact that, if not ‘done’ correctly, a vegan diet can very easily become deficient in a vast array of important nutrients, especially vitamins and minerals.

In particular, food sources of vitamins D and B12, zinc and calcium are often lacking in this diet, and when low, this can result in circadian rhythm dysregulation, shorter sleep duration, decreased REM sleep and increased risk of sleep apnoea. A vegan diet may also be low in Omega-3’s, which are found most densely in non-vegan foods such as fish. Omega-3’s are linked to increased sleep quality and quantity. 

Final word

Did this sound like a load of bad news for your sleep? The key takeaway here is that many popular diets encourage the restriction of foods that actually help our bodies thrive and the ability to get a good night’s sleep.

When it comes to nutrition, too much or too little of something can have a significant impact. If you’re on a restrictive diet and seeing benefits in some areas but deteriorations in others, consider why you’re on that diet and whether it’s truly serving you. And, as always, if you’d like to learn more about creating the best and most balanced diet for your body and unique circumstances, please reach out to a dietitian. It’s what we are here for.

Explore more content like this in our series, Ask a Dietitian. 

Health & Performance Collective is the brainchild of Sydney Dietitians Jessica Spendlove and Chloe McLeod. They use their 20 years of combined knowledge and skills as dietitians to work with motivated people to live and perform at their best.

Now you know the diets that can sabotage your sleep patterns, here are the best foods that promote good sleep.