Another involved the participants being awakened once per hour for five minutes. When researchers woke them up, they were given the same sugary beverage.
In the third test, researchers woke participants up throughout the night as in the previous experiment, but they were initially given a strong, black coffee 30 minutes prior to drinking the sugar-filled drink.
After the participants consumed the drink, researchers took blood samples. The sugary drinks reflected the same amount of calories that might typically be eaten for breakfast.
While it was discovered that one night of interrupted sleep did not make participants' breakfast-time blood glucose/insulin responses worse compared to a normal, restful night, drinking strong, black coffee ahead of breakfast time significantly increased the blood glucose response to breakfast by about 50%.
“We know that nearly half of us will wake in the morning and, before doing anything else, drink coffee – intuitively the more tired we feel, the stronger the coffee,” said professor James Betts, co-director of the Centre for Nutrition, Exercise and Metabolism at the University of Bath who oversaw the study. "This study is important and has far-reaching health implications as up until now we have had limited knowledge about what this is doing to our bodies, in particular for our metabolic and blood sugar control.
“Put simply, our blood sugar control is impaired when the first thing our bodies come into contact with is coffee especially after a night of disrupted sleep," he added. "We might improve this by eating first and then drinking coffee later if we feel we still feel need it. Knowing this can have important health benefits for us all.”
Lead researcher, Harry Smith from the Department for Health said that “individuals should try to balance the potential stimulating benefits of caffeinated coffee in the morning with the potential for higher blood glucose levels and it may be better to consume coffee following breakfast rather than before.”
Researches say the study’s results could have “far-reaching” health implications given the importance of keeping blood sugar levels in a safe range to decrease the risk of conditions, such as diabetes and heart disease, both of which are common. According to the Centers for Disease Control and Prevention, they often go hand in hand.
“There is a lot more we need to learn about the effects of sleep on our metabolism, such as how much sleep disruption is necessary to impair our metabolism and what some of the longer-term implications of this are, as well as how exercise, for instance, could help to counter some of this,” Smith said.