SLEEP PHYSIOLOGY Nonrandom Variability of Respiration During Sleep in Healthy Humans

Study objectives: Breath-to-breath variability is not purely random but is, instead, characterized by correlations on short- and long-term scales. Short-term correlations might reflect intact metabolic-control mechanisms. To investigate whether the higher variability of breathing during rapid eye movement (REM) compared to non-REM (NREM) sleep is of random or nonrandom nature—reflecting an altered respiratory control—short-term and long-term correlations of respiratory drive and timing were determined. Design: A full-night polysomnogram with a pneumotachograph attached to a full-face mask was performed. For each breath during NREM and REM sleep, respiratory components were analyzed based on the quanti-tative airflow. Setting: Data collection took place in the sleep laboratory. Participants: Twenty-nine healthy subjects (age, 25.8 ± 3.1 years). Measurements and Results: Long-term correlations are practically absent in respiratory timing and drive components during NREM sleep