The relevance of dopaminergic level in nocturnal disability in Parkinson's disease: implications of continuous dopaminergic stimulation at night to treat the symptoms. 
Sleep problems are an under-emphasized cause of disability in Parkinson's disease (PD).  Difficult sleep maintenance (light and fragmented sleep) and difficulties in initiating sleep are often the earliest and the most frequent symptoms observed in PD patients.  In fluctuating patients, nocturnal akinesia, dystonia, painful cramps, and parasomnias may aggravate nocturnal problems.  Treatment of sleep problems can be complex and challenging for the physicians.  Dopaminergic treatment may improve some of the nocturnal symptoms in PD.  In this paper, the effect of drugs and technique that ensure a more continuous delivery of dopaminergic drugs on sleep problems in PD is reviewed.