You’ve had a terrible night of fragmented sleep. You’re feeling groggy and out of sorts. So naturally, the first thing to do is drink the biggest, strongest coffee you can get your hands on. A new study from the University of Bath is suggesting that may not be the best idea. The study found a strong coffee first thing in the morning can impair the body’s glucose response, so the researchers recommend coffee should be consumed after food and not before.
“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,” says James Betts, corresponding author on the new 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.”
The new research recruited 29 healthy adults, with each subject completing three different overnight experiments. A control experiment allowed them an undisrupted night of sleep before consuming a sugary drink in the morning designed to replicate the caloric content of breakfast. This allowed the researchers to take blood samples and establish a baseline glucose and insulin response for each subject.
The two other experiments involved waking the subjects every hour overnight. They were then given the same sugary drink the next morning but in one instance the drink was preceded by a strong black coffee.
Interestingly, the study saw no impairment to the subjects’ glucose/insulin response following a single night of disrupted sleep alone. This finding was somewhat unexpected considering prior research has shown notable metabolic dysfunctions can be induced by a single night of sleep disruption.
The researchers speculate the nature of their sleep disruption intervention may not have been enough alone to trigger a metabolic dysfunction. The subjects were woken for a total of five minutes every hour throughout the night, unlike other studies on the topic utilizing more broken sleep protocols, often keeping subjects awake for an hour or two at a time.
Harry Smith, lead researcher on the study, suggests this particular finding should be reassuring to people with generally good sleep hygiene. Mild disruptions to just one night of sleep should not impair a person’s glucose response the next day.
“However, starting a day after a poor night’s sleep with a strong coffee did have a negative effect on glucose metabolism by around 50 percent,” explains Smith. “As such, 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.”
Smith says there is still a lot more work to be done to better understand the relationship between sleep and metabolism. It’s unclear, for example, how much sleep disruption is needed to disrupt a person’s metabolism. The researchers hypothesize greater disruption of slow-wave sleep phases may be more metabolically and neurophysiologically harmful than other sleep phase reductions.
Betts ultimately suggests, while much is yet to be learned, it does seem clear drinking strong coffee before eating food, and following a night of broken sleep, can limit the body’s ability to effectively tolerate sugar in breakfast.
“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,” says Betts. “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.”
New study recommends drinking coffee after breakfast, and not before [New Atlas]