The overall objective of this study is to identify the best approach for assessing the recovery function of sleep in neurodegenerative diseases associated with abnormal protein aggregation with regard to the conception of future intervention studies. To this end, the investigators will follow an exploratory approach in a preferably broad data set collected in patients with neurodegenerative diseases associated with abnormal protein aggregation and in healthy humans.

First, the investigators want to assess the relationship between sleep parameters (e.g. sleep intensity) and behavioral/cognitive performance and subjective measures (e.g. sleep quality, mood, and sleepiness) in patients with neurodegenerative disorders associated with abnormal protein aggregation. Healthy subjects will be assessed for procedure validation and reference purposes. Second, the investigators want to probe whether associations can be influenced by modulation of sleep parameters by means of auditory stimulation.

Inclusion Criteria:

• Good general health or confirmed diagnosis of neurodegenerative disease associated with abnormal protein aggregation along international criteria
• Age above 18 years
• In ambulant setting: ability to apply the ambulant EEG device for the duration of the study, either alone or with help of co-habitant if MoCA < 20

Exclusion Criteria:

• Failure to give informed consent
• Inability to follow the procedures of the study, e.g. due to language problems or cognitive deficits
• Known or suspected non-compliance, drug- or medication abuse
• Inability to hear the tones to be applied during sleep in auditory stimulation experiments
• Skin disorders/problems/allergies in face/ear area that could worsen with electrode application
• Regular intake of drugs that may alter the relationship between sleep and outcome variables under investigation (opioids, benzodiazepines and z-drugs (nonbenzodiazepines)).
• Clinically significant concomitant disease states
• Too high (disease) burden for patients
• Additional non-medical exclusion criteria may be defined for certain cognitive tasks (e.g. no glasses during experiments involving eye tracking)

During data collection, participants will be blinded to the condition, i.e. sham or verum stimulation. All experimenters will be blind for processing and analysis of outcome measures.