There is no confusion around the effect of drinking on sleep, if we drink a lot of alcohol before sleeping, we don't sleep well. However, the impact of food is not clear. How food impacts our sleep can be unique to each individual depending on how our body reacts and also how the food influences our tryptophan levels.
In this article we'll explore how our bodies respond to the consumption of food with different glycemic indices prior to sleep, and how that influences our sleep.
Before we begin we need to understand exactly what the Glycemic Index is.
Understanding the Glycemic Index
The Glycemic Index is a rating system for foods containing carbohydrates. It shows how quickly each food affects your blood sugar (glucose) level when that food is eaten on its own.
High GI foods are broken down quickly by your body and cause a rapid increase in blood glucose. High GI foods include:
- Sugar and sugary foods
- Sugary soft drinks
- White bread
- Potatoes
- White rice
Low and medium GI foods are broken down more slowly and cause a gradual rise in blood sugar levels over time. They include:
- Some fruits and vegetables
- Pulses
- Wholegrain foods such as porridge oats
A common misconception is that high GI foods are unhealthy and low GI foods are healthy, but this is not always the case. For example, watermelon and parsnips are high GI foods whilst chocolate cake has a low GI value.
Additionally, studies have shown that having high- and low- GI carb-based meals can influence the plasma concentration of tryptophan, a precursor of serotonin and sleep-inducing agent.
High-GI meals trigger the largest release of insulin and the highest ratio of tryptophan to other amino acids. This occurs because an increase in insulin allows greater absorption of neutral amino acids into muscle which leads to a greater concentration of tryptophan in the bloodstream.
How does tryptophan induce sleep?
Tryptophan is one of the many amino acids that are found in foods that contain protein. In your body, amino acids are used to make proteins but also serve other functions. Tryptophan specifically can be converted into a molecule called 5-HTP, which is used to make serotonin and ultimately, melatonin which ends up helping to induce sleep.
Tryptophan has to compete with other amino acids to enter the bloodstream. By consuming high-GI foods with the highest ratio of tryptophan to other amino acids before sleeping, we can ensure that enough Tryptophan enters the brain to enable us to sleep well.
How can we use wearables to aid us?
Combining the information from a CGM and a device that measures your sleep would be optimal to figuring out not only how your body responds to the consumption of different foods, but also how your sleep is impacted.
For example, you can look at which foods cause a spike to your blood glucose levels as measured by the CGM. When your blood glucose rises, your pancreas releases insulin into the blood which lowers your blood glucose levels back to normal levels by causing the cells to absorb it and store it as glycogen. Higher levels of insulin also enable greater absorption of amino acids, and ultimately, tryptophan - inducing better sleep. Therefore, you'll be able to determine which foods could produce a better sleep response for you personally.
To test this, you can then observe how your sleep changes over time as you adopt a new approach to the food that you eat.
Some foods you could eat before sleeping include bananas, poultry, shrimp, eggs, elk and crab (high in tryptophan). Or you can supplement your diet with tryptophan supplements and molecules that are derived from tryptophan including 5-HTP and melatonin.
Let us know how you get on!
