To investigate the efficiency and effect of a programmed slow-breathing exercise in the evening to the heart rate variability, sleep quality and memory performance over night.

Background Stress and increased alertness in the evening are major reasons for sleep onset problems, poor sleep and insomnia symptoms. For instance, increased amount of REM, and decreased amount of slow wave sleep may result. Also, the function of sleep in memory consolidation may suffer. They also affect the sleep structure and continuity during the night. They are highly prevalent phenomena among the entire population, including healthy adults and children. However, at the physiological level, the concept of evening alertness is still understudied and often neglected.

Recent advances show that breathing exercise is an efficient tool to reduce stress. However, its use specifically prior to sleep onset and with measurement sleep stages and their microstructures with sleep EEG has been little been studied before. The overall objective of this study is to explore interrelations of stress, learning and sleep quality.

Inclusion Criteria:

• age 20-45

Exclusion Criteria:

• chronic disease requiring daily medication, acute sickness (e.g. a flu), jet lag from a recent travel, current diagnosed sleep disorder (such as snoring or insomnia) and any use of medication affecting autonomic nervous system function or sleep.

10 males, 10 females