Sleep and particularly deep sleep are playing an important role for brain and body health. Poor sleep has been associated with risk factors for cardiovascular disease and moreover, is hypothesized to increased mortality risk of cardiovascular diseases. Yet, the role of specific sleep processes for cardiovascular function remains unclear. Particularly deep sleep, which is manifested by large amplitude, low frequency oscillations is of importance for the restorative functions of sleep. Thus, the modulation of deep sleep by auditory stimulation will be of central interests to assess the cause-effect relationship of specific processes within sleep for cardiovascular regulation.

This study will assess the effects of slow wave modulating auditory stimulation on cardiovasuclar functions in healthy male participants.

Inclusion Criteria:

• Informed Consent
• Good general health status
• Male subjects 18-84 years of age
• Native German speaker or good understanding of German

Exclusion Criteria:

• Contraindications on ethical grounds,
• Known or suspected non-compliance, drug or alcohol abuse,
• Regular medication intake that could pronouncedly affect outcomes of interest (e.g. beta-blocker)
• Long (> 9.5 hours per night) or short sleepers (< 6.5 hours per night),
• Smoking (regular smoker, >10 days per year, smoking not allowed during study participation)
• Participation in another study with investigational drug/therapy/interventions within the 30 days preceding and during the present study (start date adapted accordingly),
• Diseases or lesions of the nervous system (acute or residual included neurological and psychiatric diseases),
• Clinically significant concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease, etc.),
• Pacemaker,
• Intake of on-label sleep medication,
• Presence or suspicion of sleep disorders (e.g., insomnia, sleep disordered breathing (apnea), restless legs syndrome). Possibility of apnea might be assessed in the screening night,
• Body Mass Index < 18 or > 30 kg/m2,
• Irregular sleep-wake rhythm (e.g. shift working),
• Bad sleep quality during screening night (e.g. < 75% sleep efficiency in screening night)
• Significant sleep complaints in general or excessive daytime sleepiness (PSQI > 5; ESS ≥ 11),
• Travelling more than 2 time zones in the 2 weeks before experimental session starts or during intervention (start of experiment will be adapted to fit with this criteria),
• Hearing disability/ hearing aid (only an exclusion if in a simple audiometry participants cannot hear intervention tone sound levels),
• Skin disorders/problems/allergies (face region) that will significantly worsen with electrode application,
• High caffeine consumption (> 5 servings/day; including coffee and caffeinated energy drinks),