Adding sweetener to coffee enhances the ‘night vomiting’ effect of caffeine, research shows

Adding sugar or artificial sweeteners to coffee disrupted the biological clock in mice more than coffee alone, researchers have found, causing night and day to reverse in some mice. If this also applies to humans, adding sweetener to coffee would have significant health consequences.

The findings are published in the journal npj Science of Food.

If you want to freshen yourself up in the morning, or stay up late to do some work or a school assignment, most people will make themselves a cup of coffee or grab a caffeinated energy drink. These ‘night owl’ effects of this perky chemical are far from unknown.

A large number of epidemiological studies have shown how night-oriented people tend to drink more caffeinated drinks than morning people, and animal and cell experiments have shown how caffeine works to extend the waking period of the internal body clock.

But a group of researchers accidentally discovered that changes in mice’s activity rhythm were affected even more when they mixed caffeine with sugar or other sweeteners.

“We examined the characteristics of male mice’s behavior while drinking sweetened caffeine water in general, and found interesting behavioral changes that we did not expect,” said Yu Tahara, associate professor at the Graduate School of Biomedical and Health Sciences at the Hiroshima University. . “So we focused our research on these sugary effects.”

The team gave sweetened caffeine water with 0.1% caffeine, which is half the concentration of espresso, and 1% sucrose, which is one-tenth the concentration of most energy drinks, or 0.1% saccharin.

“The added sweetness did not change the amount of caffeine water the mice drank, so the effects could not have been the result of just drinking more caffeine,” Tahara added. “It had to be the combination of caffeine and sweetener.”

The mice that consumed the caffeine-sweetener mix experienced a very long “free-running” sleep-wake period of 26 to 30 hours, and some even switched from a nighttime circadian rhythm to a diurnal rhythm.

These effects continued to occur even when the mice were exposed to persistent darkness. This latter phenomenon suggests that the caffeine sweetener effect works independently of the central regulator of the internal body clock, the suprachiasmatic nucleus (SCN), located in the hypothalamus in the brain. That central regulator itself is normally controlled by light and the natural day-night cycle, and in turn ensures synchronization of clocks located in organ tissue elsewhere in the body.

The researchers believe that the combination of caffeine and sweets may create a conflicting signal in the body, possibly mediated by another famous chemical, dopamine. Both caffeine and sweeteners activate the reward system in the brain, leading to the release of dopamine. It is this double dose of dopamine that could contribute to the creation of long-lasting activity rhythms.

The researchers now want to further investigate the possible dopamine link and see whether the caffeine boost produced by a sweetener is replicated in humans. Although this first study only looked at the effects in mice, the findings could have important implications for our understanding of how sweetened caffeine affects human health.

Many health authorities recommend an upper limit on the amount of caffeine consumed per day, or recommend reduced consumption in the evening or night, as excessive amounts are associated with reduced sleep quality and increased night-time vomiting tendencies, which in turn trigger a range of have negative physical consequences. and mental health effects.

This research adds another layer to this advice, suggesting that adding sweeteners to caffeine may further exacerbate any negative effects.

On the other hand, the researchers would also like to investigate the effects of caffeine and sweetener intake in the morning.

“If you want to be even perkier in the morning, you might want to make sure you have your coffee for breakfast with something sweet,” Tahara said.