Auditory Sleep Stimulation or Sham in People With Parkinson Disease Mild Cognitive Impairment During Cognitive Training

Inclusion Criteria: * clinical diagnosis of PD along the MDS criteria (Postuma et al., 2015) * MCI according to the MDS criteria, level I (Litvan et al., 2012): * \- cognitive decline: Gradual decline, in the context of established PD, in cognitive ability reported by either the patient or informant, or observed by the clinician, AND * \- MoCA ≤ 26 and ≥ 18 (Hoops et al., 2009) * stable home situation (e.g. long-term place to live) that allows for reliable application of intervention for the duration of the study * ability to apply the sleep intervention for the duration of study, either alone or with assistance of a co-habitant if needed * ability to apply the CogT intervention for the duration of study * sufficient German language comprehension to follow the study procedures and answer all questions related to the study outcomes * dosing of dopaminergic and other PD treatment must have been stable for at least 14 days prior to the intervention period and will be expected to remain stable until the end of the study. Exclusion Criteria: Diagnosis/Comorbidities: * clinical diagnosis of dementia (cognitive impairment sufficient to interfere with independence in everyday activities, i.e. "major neurocognitive disorder", DSM-5) * known presence of neurologic (other than PD) or psychiatric disorder * Parkinsonism without response to levodopa; atypical Parkinsonian syndromes as assessed from medical history and clinical examination * severe medical conditions (for example, rena…