Researchers from the University of Sydney conducted an experiment involving 48 people who consumed large amounts of caffeine. Each participant drank at least 270 milligrams of caffeine each day, the equivalent of three cups of coffee.
The Australian investigators wished to determine if caffeine withdrawal is real or imaginary. They told each participant about the dose reductions and measured how that affected the person’s own opinion on the severity of his withdrawal.
The researchers assigned the participants into two groups at random. Both groups went through the same caffeine reduction plan for five days.
During the first day, the participants received one cup of coffee in the morning and a second cup during the afternoon. Their caffeine intake totaled 300 mg.
They continued to drink the same amount of coffee on the second, third, fourth, and fifth days. However, the researchers gradually reduced the caffeine levels each day.
As such, the participants got 200 mg of caffeine on the second day, 100 mg on the third day, and no caffeine during the fourth and fifth days.
Each group also received different information about their caffeine reduction plan. The participants in one group got accurate data on their reduction schedule.
However, the second group received deliberately incorrect data on their caffeine intake. The Sydney researchers told them that they got 300 mg of caffeine during the first, second, and third days of the study and zero caffeine during the fourth and fifth days. (Related: Nootropics: Not just a fancy way of saying brain vitamins.)
On each day of the experiment, the participants answered questionnaires that analyzed their levels of caffeine withdrawal. The survey measured various symptoms associated with it.
The Sydney researchers compared the survey scores of the two groups. They theorized that the symptoms of caffeine withdrawal would reflect the information that the participants received, rather than the doses they received.
The results of their analysis confirmed their theory. The participants who received real information about the reduction of caffeine doses reported a steady increase in withdrawal symptoms as the five-day test period wore on.
Meanwhile, the participants who got misled about their caffeine reduction doses recorded the same scores during the first three days. They reported a sharp spike in withdrawal symptoms on the fourth day.
“Given that they received identical doses of caffeine, these day-to-day differences in reported withdrawal can only be explained by differences in expectancies,” the Sydney researchers reported.
The final results of the experiment suggest that both groups might have been biased in reporting their symptoms.
The placebo effect might have influenced the incorrectly-informed group. This effect usually makes people believe that they are receiving something effective when, in fact, no such thing is being given.
At the same time, the group that received accurate information might have experienced the opposite "nocebo effect," which refers to when people display the negative side effects known to be associated with a treatment.
The takeaway from this study is that people who are trying to cut back on caffeine may be able to take advantage of their expectations. If they convince themselves that they are still getting their usual amount of coffee even though they are not, they may successfully kick the habit eventually.