In recent years, it has become common for people to reach for sweet coffee drinks or energy drinks when they feel mentally tired after working on a computer or playing video games. While these drinks are thought to temporarily alleviate fatigue, increased intake of sugar and caffeine can also lead to lifestyle-related diseases. Takahashi and his team focused on unsweetened, highly carbonated water and conducted their study in collaboration with Asahi Soft Drinks Co., a major carbonated beverage manufacturer. The study utilized e-sports that require quick decision-making and careful attention to detail. Fourteen men and women with an average age of 22.9 played a soccer video game for three hours. Participants drank highly carbonated water every hour and repeatedly underwent tests to check their fatigue levels and measure their blood glucose levels and heart rates. On another day, they played the same game while drinking uncarbonated water to see if it produced similar effects.