Researchers at the University of British Columbia conducted a study on rats using caffeine and amphetamines. The researchers say there are two types of rats in this world: slacker rats that typically avoid challenges and worker rats that typically embrace challenges.
The researchers report
that when presented with stimulants, the "slacker" rats that usually avoided challenges worked significantly harder when given caffeine and amphetamines. However, the "worker" rats that typically embraced challenges became less motivated when given caffeine or amphetamine.
Jay Hosking, a PhD candidate in UBC's Dept. of Psychology, who led the study, says, "Every day, millions of people use stimulants to wake up, stay alert and increase their productivity - from truckers driving all night to students cramming for exams. These findings suggest that some stimulants may actually have an opposite effect for people who naturally favor the difficult tasks of life that come with greater rewards."
There has already been anecdotal evidence
that caffeine may have a calming effect on people with ADHD.