Sudden onset of sleep and dopaminergic therapy in patients with restless legs syndrome.

BACKGROUND AND PURPOSE: Sudden onset of sleep (SOS) was recently reported in patients with Parkinson's disease (PD) under dopaminergic treatment. Here, we investigated as to what extent SOS is found in patients with restless legs syndrome (RLS), who are frequently treated with dopaminergic drugs, and controls. PATIENTS AND METHODS: A questionnaire survey on SOS was administered to 156 RLS patients and 126 controls. RESULTS: While no significant difference between RLS patients and controls was detected in Epworth sleepiness scale (ESS) scores (P=0.76), the prevalence of SOS was higher in RLS patients (32.7%) than in controls (19.8%) (P=0.02). Significant predictors of SOS in RLS were ESS score (odds ratio (OR) 16.4), male sex (OR 4.6), duration of night-time sleep (OR 3.0), and age (OR 2.9), while no association was observed for duration or severity of the disease. Patients on dopaminergic therapy usually featured a lower risk of SOS than untreated patients. Falling asleep while driving was reported by 14.6% of all RLS patients with a driver's license and associated with increased risk of accident (OR 7.1). CONCLUSIONS: RLS patients who are untreated, male, and elderly should be assessed for the presence of SOS. In contrast to PD, dopaminergic drugs may reduce the risk of SOS in RLS. The possible benefit of the drugs should be investigated particularly in male patients.

Daytime sleep latency in medication-matched Parkinsonian patients with and without sudden onset of sleep.

Currently, it is unclear whether sleep attacks in Parkinson's disease (PD) represent a novel entity or just a phenomenon of daytime sleepiness. We investigated 10 PD patients with sleep attacks and compared them with 10 PD patients without any daytime sleepiness. The patients were matched according to their dopaminergic medication and subjected to a sleep medical investigation. The mean sleep latency on the multiple sleep latency test was in the normal range and not significantly different between the groups. These data suggest that sleep attacks can occur against a background of normal alertness.

Driving in Parkinson's disease: mobility, accidents, and sudden onset of sleep at the wheel.

Only few studies have addressed driving ability in Parkinson's disease (PD) to date. However, studies investigating accident proneness of PD patients are urgently needed in the light of motor disability in PD and--particularly--the report of "sleep attacks" at the wheel. We sent a questionnaire about sudden onset of sleep (SOS) and driving behavior to 12,000 PD patients. Subsequently, of 6,620 complete data sets, 361 patients were interviewed by phone. A total of 82% of those 6,620 patients held a driving license, and 60% of them still participated in traffic. Of the patients holding a driving license, 15% had been involved in and 11% had caused at least one accident during the past 5 years. The risk of causing accidents was significantly increased for patients who felt moderately impaired by PD, had an increased Epworth Sleepiness Scale (ESS) score, and had experienced SOS while driving. Sleep attacks at the wheel usually occurred in easy driving situations and resulted in typical fatigue-related accidents. Those having retired from driving had a more advanced (subjective) disease severity, higher age, more frequently female gender, an increased ESS score, and a longer disease duration. The study revealed SOS and daytime sleepiness as critical factors for traffic safety in addition to motor disabilities of PD patients. The results suggest that real sleep attacks without any prior sleepiness are rare. However, our data underline the importance of mobility for patients and the need for further studies addressing the ability to drive in PD.

Dopamine receptor gene polymorphisms in Parkinson's disease patients reporting "sleep attacks".

Genes encoding proteins involved in dopaminergic transmission are potential candidate genes for the induction of somnolence in Parkinson's disease (PD) because dopaminergic agents have been shown to be associated with sudden onset of sleep (SOS) in PD. We conducted an association study on dopamine D2, D3, and D4 receptor gene polymorphisms comparing 137 PD patients with SOS and 137 PD patients without SOS matched according to drug therapy, disease duration, sex, and age. Our results show a significant association between the dopamine D2 receptor gene polymorphism Taq IA and SOS in PD. No significant association between two other investigated polymorphisms and the phenomenon of "sleep attacks" in PD was observed.

Predictors of sudden onset of sleep in Parkinson's disease.

With respect to the ongoing discussion of "sleep attacks" in Parkinson's disease (PD), we sought to estimate the prevalence of sudden onset of sleep (SOS) with and without preceding sleepiness in PD, to identify associated factors, and to define the role of antiparkinsonian medication in SOS. We sent a questionnaire about SOS, sleep behaviour, and medication to 12,000 PD patients. The response rate was 63%, from which 6,620 complete data sets could be analysed. A total of 42.9% of our population reported SOS, 10% of whom never experienced sleepiness before the appearance of SOS (4.3% of all), and we identified the administration of all dopaminergic drugs as a risk factor for SOS. However, SOS occurred earlier after introduction of nonergoline dopamine agonists (DA) and was more strongly associated with nonergoline DA in younger patients (below 70 years) with a shorter disease duration (up to 7 years) but, actually, medication was less efficient in predicting SOS than most other factors considered such as higher age, male sex, longer disease duration, and the report of sleep disturbances. This survey strongly suggests that SOS is a multifactorial phenomenon. Some subgroups are at particular risk of experiencing SOS under nonergoline DA, especially at the beginning of this therapy. Our results support the current notion that SOS, in part, can be attributed to PD-specific pathology because disease duration and subjective disease severity have been shown to be predictors of SOS. We recommend the development of a standardised question to recognise SOS and to facilitate the comparison of prevalence estimates.