Could the sweetened drinks we're consuming be making us feel a little more anxious? A 2022 study looking at the effects of the artificial sweetener aspartame on mice suggests that it's a possibility that's worth investigating further.
They're providing a sweetener at all times. That alone would have some affect, so I'd think you'd want another sweetenere like sucrose, glucose, some other artificial sweetener, in addition to a water treatment. Alternatively, a dose response could be informative. They did have different doses of aspartame, but in both groups of mice (male and female), the dose response was opposite what you'd expect; the lower dose had a larger effect.