Caffeine for Excessive Daytime Somnolence in Parkinson's Disease

Many patients with Parkinson's disease (PD) have sleep problems, including excessive sleepiness during the day. This is probably due to degeneration of sleep-regulating areas in the brain. At present, the only treatment for sleepiness in PD is modafinil, which is expensive and only partially effective. There is another potential treatment for sleepiness that is used worldwide, is inexpensive, well tolerated and safe - namely, caffeine. There have also been suggestions that caffeine may slow the progression of degeneration in PD, since coffee non-drinkers are at higher risk of developing PD. PD patients, even with severe sleepiness often do not use caffeine. It is unclear whether this is because their PD makes their sleepiness unresponsive to caffeine, because they cannot tolerate it, or whether this reflects their lifelong habit of non-use. This proposal outlines a trial in which patients with excessive sleepiness will be given caffeine or placebo (no therapy) in a blinded fashion. In this way, the effect of caffeine on sleepiness and motor symptoms can be directly analyzed. In addition, these findings can be used to test the tolerability of caffeine, to help plan a larger-scale study testing whether caffeine can slow the progression of PD