Does Acoustic Stimulation During Sleep Boost Slow Wave Sleep and Memory Performance?

Improving Slow Wave Sleep by Auditory Stimulation to Enhance Memory Consolidation and New Learning in Healthy Older Adults and Older Individuals at Risk for Dementia

With aging the amount of slow wave sleep decreases drastically and this disruption is markedly exaggerated in older adults suffering from mild cognitive impairment and Alzheimer's disease. Critically, the disruption of slow wave sleep and cognitive decline seem bidirectionally linked forming a vicious cycle. In the long run, improving slow wave sleep might be a useful intervention tool to delay the onset of cognitive decline. The present study aims at improving slow wave sleep and memory functions through a closed-loop acoustic stimulation approach. A closed-loop algorithm is used that detects slow waves in the electroencephalogram and is programmed to present short tones (50 ms) in the rhythm of these waves. This procedure has shown to boost both slow wave sleep as well as memory performance, mainly in young adults and when applied for one night. Here, the investigators apply tones via multiple consecutive nights and assess memory performance during this 3-night intervention.

Inclusion Criteria:

• Written informed consent
• Fluent in German
• Normal or corrected to normal vision
• Unimpaired hearing
• For healthy group: Montreal Cognitive Assessment Score ≥ 26
• For MCI group: Montreal Cognitive Assessment Score < 26
• For at risk group: smoker, high cholesterol, high blood pressure and high fasting plasma glucose OR smoker, high BMI, physically inactive, unhealthy dietary habits

Exclusion Criteria:

• Known sleep problems such as Insomnia, restless leg syndrome, apnea
• Irregular sleep pattern
• Symptoms of depression
• History of untreated severe neurological and psychiatric diseases
• Alcohol or substance abuse
• Use of medication acting on the central nervous system