Amsterdam, NL, 10 July 2014 – Up to 70% of Parkinson's disease (PD) patients experience sleep problems that negatively impact their quality of life. Some patients have disturbed sleep/wake patterns such as difficulty falling asleep or staying asleep, while other patients may be subject to sudden and involuntary daytime sleep "attacks." In the extreme, PD patients may exhibit REM-sleep behavior disorder (RBD), characterized by vivid, violent dreams or dream re-enactment, even before motor symptoms appear.