by Kerry Potter
As a follow-up to my last article on sleep, I would like to address the importance of nutrition in relation to sleep time and quality. Many people do not realize that not only can a lack of sleep affect how we eat, but vice versa. What we eat during the day and close to bedtime can affect our quality of sleep. As I mentioned in my last article, I have become very interested in sleep because I am not the best sleeper myself and I know I am not alone in this problem. Recently, I have been experimenting with different nutrition strategies throughout the day to see how it affects my sleep and my energy the following day.
According to the National Sleep Foundation, certain foods contain an amino acid called tryptophan that causes sleepiness. Tryptophan is an essential amino acid in the human diet. Different types of protein sources, including plant protein sources, can be high in this particular amino acid. Furthermore, foods high in the macronutrient carbohydrate can also make tryptophan more available to be taken up by the brain to promote sleepiness. This is possible because ingestion of a meal rich in carbohydrates triggers the release of insulin. Insulin promotes the uptake of branched-chain amino acids into the muscle while leaving tryptophan to be taken up by the brain. Based upon this information, the best bedtime snack is one that contains both a carbohydrate and protein. However, too heavy of a carbohydrate meal earlier in the day could leave us feeling very drowsy.
After reading this, I wondered if carbohydrate quality and quantity at night also plays a role in sleep. Does the glycemic index of the carbohydrate matter? According to one study (High-glycemic Index Carbohydrate Meals Shorten Sleep Onset by Afaghi), they hypothesized that a high glycemic index meal would cause a greater insulin response in healthy sleepers causing them to fall asleep faster and have a better quality of sleep throughout the night. The study concluded that individuals fell asleep more quickly (an average of 10 to 15 minutes) when they ingested a high glycemic, high carbohydrate meal four hours before bedtime in comparison to a low glycemic index carbohydrate rich meal an hour before bedtime.
Caffeine is a tricky one and, when deciding if and when to consume it, needs to be looked at on a case by case basis. We all have small genetic differences. This explains why we respond differently to all types of foods. In regard to caffeine, we all have a specific enzyme to breakdown caffeine. However, because of our small genetic variations, one person may have the enzyme that breaks down caffeine quickly while another individual breaks caffeine down quite slowly. This is why caffeine can persist in certain people’s bodies for several hours after consumption and disrupt sleep through the night.
I have never been a big drinker (alcohol that is, I love water!), but I have many friends who are social drinkers or enjoy a glass or two of wine with dinner or in the evening. Although at first we may become sleepy with alcohol, it can disrupt the 5 stages of sleep that I spoke about in my last article. It can disrupt sleep over the course of the night by not allowing us to enter the deeper stages of sleep (stages three, four, and REM). So even though you may have slept seven-plus hours, you may find yourself exhausted later the next day or not waking up refreshed because you were never in a deep sleep.
Another interesting aspect of sleep relates to all the sleep aides on the market. A very popular one that comes to mind is melatonin. Melatonin is a naturally occurring hormone that helps promote restful sleep. It is the end product made when tryptophan converts to serotonin then to melatonin. This is what keeps us asleep during the night. However, even though this supplement is still widely used, scientific evidence shows little benefit of melatonin improving an individual’s sleep. This may be due to people not changing other nutritional habits that may be hindering their sleep.
Finally, after all my research and studying, this is what I have concluded about sleep and nutrition…there is no conclusion! We are all so unique and are affected differently by food. What I can conclude is that it’s important to take all the above information and use it to your advantage to help you discover how nutrition does affect your sleep. Keep a food and activity journal and change one nutritional variable every 4 to 7 days and see how that affects your sleep. I have learned a lot about myself in these last couple of weeks just by being more mindful of how I sleep and what I eat.
References: www.sleepfoundation.org Afaghi A, O’Connor H, Chow CM. High-glycemic-index carbohydrate meals shorten sleep onset. Am J Clin Nutr 2007;85:426 –30. Fernstron JD, Wurtman RJ. Brain serotonin content: increase following ingestion of carbohydrate. Science 1971;174:1023–5
