This study is important even though it failed to reveal a benefit for caffeine in improving sleepiness and no changes in quality of life, depression or sleep quality in study participants of Parkinson's disease. Interestingly, it did reveal a clinically significant potential motor benefit. This is one of the first studies in humans to show that caffeine can help with movement symptoms for people who already have the disease, compared to their caffeine-free counterparts. It will be interesting to see if these findings hold up, and caffeine becomes a treatment approach in Parkinson disease.