This is a randomized, placebo-controlled, 3-way cross-over phase IIa trial comparing two dose levels of THN102 to placebo in patients suffering from Parkinson's disease associated with excessive daytime sleepiness.

The treatment duration is 2 weeks per period. Each treatment period is followed by a one-week washout period.

Inclusion Criteria:

• Subjects with a diagnosis of idiopathic Parkinson's disease as defined by the Movement Disorders Society (MDS).
• Subjects with Hoehn and Yahr scale score ≤ 4.
• Body mass index > 18 kg/m2 and < 35 kg/m2.
• Subjects should have a complaint of daytime sleepiness impacting their quality of life and/or daytime functioning (e.g. falling asleep while reading or watching television, while eating or talking with other people).
• Epworth Sleepiness Scale (ESS) score ≥ 14.

Exclusion Criteria:

• Subjects with known or with a suspected sleep apnea syndrome or who have any other cause of excessive daytime sleepiness, such as shift work sleep disorder.
• Psychiatric and neurological disorders (other than Parkinson's disease),
• Cardiovascular disorders such as - but not limited to
• Uncontrolled moderate to severe hypertension
• History or current diagnosis of electrocardiogram (ECG) abnormalities indicating significant risk of safety for patients participating in the study
• Recent myocardial infarction
• Stable or unstable angina pectoris
• Cardiac insufficiency or history of heart failure
• Previous history of cardiac valvular surgery
• Subjects with current impulse control disorder.
• Subjects showing dementia or with MoCA < 23.
• Subjects with current suicidal risk
• Current or recent (within one year) history of substance abuse or dependence disorder
• Other active clinically significant illness
• Subjects with hepatic or renal impairment