Adjust Text Size:change font sizechange font sizechange font sizechange font sizechange font sizechange font size

Access to the latest research — for scientists and people living with PD alike — in PDF's new scientific journal.

Browse Now

Parkinson's HelpLine


Learn More

Science News

Hallucinations and Sleep Disorders Are Unrelated in Parkinsonís Disease

Sleep problems such as vivid dreams are not associated with increased risk of developing hallucinations for people with Parkinson’s disease (PD), according to a study in the October 20 online issue of Neurology.  Although people with PD who have hallucinations often do have sleep difficulties, the two issues may not be related and they progress differently.  

Sleep difficulties are common for people with Parkinson’s.  The most common sleep difficulties include sleep fragmentation (tendency to wake up multiple times at night), acting out dreams (REM sleep behavior disorder) and vivid dreams.  Traditionally, vivid dreams were considered as an early manifestation of hallucinations, and were treated similarly.  Many people with mid- or late-stage PD experience hallucinations, which may be exacerbated by PD medications.

To understand the relationship between hallucinations and sleep disorders, a team of researchers at Rush University Medical Center led by Christopher G. Goetz, M.D., followed 89 people with PD for 10 years.  At the time of enrollment in the study, 60 participants had never hallucinated but had a range of sleep disturbances and 29 had experienced hallucinations.  

On average, participants were 68 years old and had been diagnosed with PD for ten years.  All were taking levodopa; about half also took other PD medications, including sleep medications.  The researchers used standard assessments to rate the quality of participants’ sleep and the presence and frequency of hallucinations after six months, 18 months, four years, six years and 10 years. 



  • During the course of the study, the percentage of participants who experienced hallucinations nearly doubled.
  • Hallucinations tended to become more frequent and more severe over time for people who experienced them.
  • Acting out dreams was the only sleep disturbance that progressed over time, having occurred in 12 percent of participants at the beginning of the study and in 33 percent at 10 years.
  • Sleep disturbances including frequent waking during the night, vivid dreams, and daytime sleepiness did not worsen over the course of the study.
  • People who reported sleep disturbances in the beginning of the study did not have an increased  risk of developing hallucinations.
  • No association was found between the dose of levodopa and the occurrence of hallucinations.



What Does it Mean?

This study disproves the common notion that vivid dreams are a mild form of hallucinations.  The study authors also point out that no hallucinations should be considered “benign,” as this symptom most often becomes chronic and progresses over time.  In addition, the researchers note that four study participants never developed hallucinations.  Further studies of such people may provide clues to understanding what factors may protect against hallucinations.


Learn More

PDF's recent online seminar discussed, "Fatigue, Sleep Disorders and Parkinson's."

Watch the Online Seminar


Reference: Hallucinations and sleep disorders in PD: Ten-year prospective longitudinal study. Goetz CG, Ouyang B, Negron A, Stebbins GT. Neurology. 2010 Oct 20. (


Source Date: Nov 01 2010