A sleepless night and immediately we run to the kitchen to drink a strong coffee, to wake up and face a new day. However, this does not seem a healthy habit, at least based on a recent scientific research that appeared in the British Journal of Nutrition thanks to the work of a team of British researchers from the University of Bath (Smith et al, British Journal of Nutrition, 2020).
Scientists tried to understand the kind of impact a sleepless night and subsequent a strong coffee may have on metabolism and, in particular, on blood glucose. 30 people with an average age of 21 were recruited. All study participants underwent three experiences at random. First, the study participants, after a night of uninterrupted sleep, drank a sugary drink that, by calories, was comparable to a normal breakfast. Second, the participants experienced a night of interrupted sleep, in which they were awakened every hour for 5 minutes. After the night they took the sweetened drink. Third, after a night of interrupted sleep every hour for 5 minutes, the study participants were asked to drink strong coffee and only after 30 minutes to take the sweetened drink. After the drink, all participants were subjected to a blood glucose test. What emerged was that a disturbed night of sleep did not lead to changes in blood sugar compared to a normal night of sleep. Instead, drinking strong coffee before breakfast led to a 50% increase in blood sugar in response to the sugary drink. Thus, the habit of drinking strong coffee after a disturbed night of sleep certainly helps to wake up and regain energy but can reduce the body's tolerance of the sugars ingested with breakfast, paving the way, in the long run, to problems such as diabetes or cardiovascular disease. Therefore, if, after a disturbed night of sleep, we feel the need to drink a nice cup of coffee, the researchers' advice is to have breakfast first and then drink coffee.