Study of the Symptomatic Effects of Nocturnal Sodium Oxybate in Parkinson's Disease

Inclusion Criteria: * Moderate to severe Parkinson's disease (Hoehn and Yahr II/III) diagnosis according to international criteria \[14\], * History of disturbed nocturnal sleep and presence of EDS (ESS \>10 points), * Doses of dopaminergic and other PD treatment must have been stable for at least 14 days prior to the screening visit, * Negative pregnancy test prior to inclusion (except in women who are surgically sterilized/hysterectomized or post-menopausal for longer than 2 years), * Patients are capable of giving informed consent, * Signed Informed Consent after being informed. Exclusion Criteria: Atypical Parkinson disorder, Parkinson's disease without response to levodopa, * AHI \>15 or oxygen saturation consistently below 90% on baseline polysomnography * diagnosis of sleep apnoea-syndrome or COPD * Severe dementia (MoCA\<22), * Moderate to severe depression (HADS\>15). * Contraindications to the class of drugs under study, e.g. known hypersensitivity or allergy to class of drugs or the investigational product, * Regular use of CNS depressant substances (opioids, barbiturates) as well as melatonin and other sleep-inducing substances, * Other clinically significant concomitant disease states (e.g., renal insufficiency (creatinin \> 120 resp. GFR \<40ml/min), hepatic dysfunction (GPT \> 100U/l), severe cardiovascular disease, etc), * Known or suspected non-compliance, substance or alcohol abuse (i.e. \> 0.5 l wine or 1 l beer per day), * Homeless persons, * Women who…