A study conducted by researchers from the Graduate School of Biomedical and Health Sciences at Hiroshima University has revealed that coffee sweetened with sugar or artificial sweeteners has a significantly stronger effect on biological rhythms than unsweetened coffee. These findings, published in the journal Science of Food, mark a significant step in understanding how caffeine impacts the human body.
How Does Sugar Amplify Caffeine’s Effects?
Caffeine is well-known for influencing circadian rhythms—the internal clock regulating sleep and wake cycles. However, the study demonstrated that adding natural sugar or artificial sweeteners, such as saccharin, amplifies this effect. Mice consuming caffeine mixed with sweetened water exhibited a dramatic shift in their circadian rhythms, extending their activity and sleep cycles to 26–30 hours.
The Experiment
In the study, researchers provided mice with two types of beverages:
- Sweetened water containing 0.1% caffeine and either 1% sucrose or 0.1% saccharin.
- Unsweetened water containing 0.1% caffeine.
Both groups consumed similar amounts of liquid, but the mice drinking sweetened water showed longer activity periods and notable changes in their usual circadian rhythms. Remarkably, some mice even shifted from nocturnal to diurnal behavior—a rare occurrence.
Independence from Light
One of the experiment’s key findings was that these changes in biological rhythms occurred even in constant darkness. This indicates that the effects of caffeine combined with sweeteners operate independently of signals from the body’s central “clock”—the suprachiasmatic nucleus in the brain.
The Mechanism Behind the Effect
Researchers suggest that the combination of caffeine and sugar sends conflicting signals to the body:
- Activation of the reward system: Sweetened beverages trigger the release of dopamine, a neurotransmitter associated with pleasure and motivation.
- Disruption of biological processes: The sweetened drink alters the normal sleep-wake cycle, disrupting the body’s natural rhythms.
Implications for Humans
Although the experiment was conducted on mice, researchers plan to investigate whether similar effects occur in humans. If proven, this could explain why coffee with sugar often produces a more pronounced boost in energy and alertness than caffeine alone. Additionally, it highlights how dietary habits may influence circadian rhythms and overall health.
Conclusion
The combination of caffeine and sweeteners—both natural and artificial—has a profound impact on biological rhythms. This discovery could have significant implications for individuals who rely on coffee to stay energized. At the same time, it underscores the importance of further research into the relationship between dietary choices, stimulants, and our internal “biological clock.”
For more information, refer to the original study in Science of Food.