We are what we eat, but we also sleep how we eat. With this sentence it is possible to summarize the very interesting research we are talking about today. The study, published some time ago in The American Journal of Clinical Nutrition by an American team from Columbia University (Gangwisch et al, AJCN, Dec 2019), highlights the link between a diet high in refined carbohydrates and the insomnia.
The problem of insomnia
It is estimated that insomnia affects almost 30% of the adult population with a worsening of the quality of life, a decrease in attention and mood and a feeling of daytime fatigue. To treat insomnia, psychotherapy can be used, which is expensive, both in terms of time and from an economic point of view, or drugs, which can cause annoying side effects This is why scientists are constantly looking for techniques and modifications in lifestyle, simple and affordable for everyone, which can improve the quality of sleep. We have already seen, based on previous articles, how some essential oils such as lavender, bergamot and ylang ylang can make sleep more restful and reduce the time to fall asleep. Today we are talking about the effects of diet, and in particular of refined carbohydrates, on sleep quality.
Diet and sleep, a fascinating link
Scientists have started from the hypothesis that refined carbohydrates, that is, those with a high glycemic index such as white bread, refined rice, refined pasta, sweets and packaged snacks, can cause insomnia. This is due to a reaction that is triggered in the body. In fact, refined carbohydrates cause a spike in blood sugar to which the body responds with an increase in insulin. This, in turn, causes a sudden drop in blood sugar, which is followed by the release of hormones such as adrenaline and cortisol, which can interfere with sleep. This hypothesis could be contested by stating that, as indicated by numerous scientific studies, carbohydrates are able to stimulate the release of tryptophan, a precursor of serotonin and melatonin, essential for regulating the sleep-wake rhythm. However, two factors need to be considered, as the study authors themselves point out. First of all, for carbohydrates to stimulate tryptophan the meal must not contain proteins, already a percentage of 2.5% of proteins significantly reduces the amount of tryptophan released. Foods with a high glycemic index such as ice cream, milk chocolate, sweetened yoghurt and cakes contain enough protein to block tryptophan. Then, in any case, even if the amount of tryptophan were to increase, an increase in melatonin would not follow since dark or even artificial light inhibits the synthesis of melatonin. Until now, studies on the link between a diet rich in refined carbohydrates and insomnia have not been conclusive as people have never been followed for a long period of time in order to exclude that it was insomnia that caused an increased consumption of refined carbohydrates.
Refined carbohydrates increase the risk of insomnia
To fill this gap, scientists have developed the study we are talking about today. The researchers drew on data from more than 50,000 postmenopausal women who joined a large study, the Women's Health Initiative, which began in 1991 to assess the health status of postmenopausal women. Participants in the study were asked to fill in a diary for three years, from 1998 to 2001, indicating diet and sleep quality. Extrapolating the data, the scientists observed that a diet high in refined carbohydrates can cause an increased risk of insomnia. In fact, in the three years of analysis, people who had, at the beginning of the study, a diet high in refined carbohydrates, had gradually begun to experience insomnia.
Here is another proof that what we eat can affect different areas of our life and health, even those not directly related to food. A varied and healthy diet, based on whole grains, fruits and vegetables, is certainly a good choice also to ensure restful and peaceful sleep. And to the question why fruit, while containing sugars capable of increasing blood sugar, is not pointed out as a possible cause of insomnia, the authors reply that in the whole fruit, not in the juices, carbohydrates and fibers coexist. The latter slow down the absorption of carbohydrates, by reducing the glycemic index and protecting from an increase in the hormones adrenaline and cortisol and from the risk of developing insomnia caused by a high glycemic index diet.