Adding sugar or artificial sweeteners to coffee could have a surprising impact on your body clock, according to new research from Hiroshima University.
Scientists found that sweetened coffee disrupted the natural sleep-wake cycle in mice more than coffee alone, even causing some to switch their activity patterns from night to day.
If this holds true for humans, it could have significant health implications.
Most people rely on caffeine to wake up in the morning or stay up late to finish work.
Caffeine, a stimulant, is well-known for its “night-owl” effects, helping people stay alert by extending their internal waking period.
However, researchers accidentally discovered that combining caffeine with sugar or sweeteners creates even stronger disruptions to the body clock.
The study, published in npj Science of Food, began as a general investigation into how male mice behaved when drinking sweetened caffeine water.
“We noticed unexpected changes in their behavior,” said Yu Tahara, associate professor at Hiroshima University. This led the researchers to focus on the effects of caffeine combined with sweetness.
Mice were given caffeine water mixed with either sugar (sucrose) or an artificial sweetener (saccharine).
Surprisingly, the amount they drank didn’t change, meaning the effects weren’t simply from consuming more caffeine. Instead, it was the combination of caffeine and sweetener causing the changes.
Mice that consumed the sweetened caffeine water experienced a much longer sleep-wake cycle of 26–30 hours, instead of the usual 24 hours.
Some even switched their natural nocturnal patterns to being active during the day.
These effects persisted even when the mice were kept in complete darkness, suggesting the disruptions were not tied to the usual light-based regulation of the body clock.
The researchers believe the combination of caffeine and sweeteners may send conflicting signals to the brain, possibly involving dopamine, a chemical linked to the brain’s reward system. Both caffeine and sweetness trigger dopamine release, and this “double hit” might be responsible for the unusual effects on activity rhythms.
Although this study was conducted on mice, it raises questions about how sweetened coffee affects humans. Many health guidelines already warn against consuming too much caffeine, especially in the evening, as it can lead to poor sleep and other health problems. Adding sweeteners may make these effects worse.
On the flip side, researchers are curious about whether the combination could enhance morning alertness. “If you want to feel extra perky in the morning, sweetened coffee might give you a bigger boost,” said Tahara.
Further studies are needed to confirm if these findings apply to humans, but the research suggests rethinking how sweeteners in coffee might affect your health and daily rhythms.
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Source: KSR.
