Physiological relationship between autonomic reactions and arousals in infancy

Area of Science:

• Pediatric Sleep Medicine
• Autonomic Nervous System Function
• Cardiovascular Physiology

Background:

• The prone sleeping position is associated with an increased risk of Sudden Infant Death Syndrome (SIDS).
• Autonomic responses during sleep, such as blood pressure (BP) regulation, are crucial for arousal and survival.
• Understanding how sleep position affects autonomic responses is important for infant safety.

Purpose of the Study:

• To investigate the impact of prone versus supine sleeping positions on blood pressure (BP) and autonomic responses to auditory stimuli in infants and children.
• To explore the relationship between sleep position, arousal thresholds, and cardiovascular regulation.

Main Methods:

• Polygraphic recordings were conducted on newborns, infants, and children during one night in both prone and supine positions.
• Auditory stimuli (white noise) of increasing intensity were presented during rapid eye movement (REM) and non-rapid eye movement (NREM) sleep.
• Blood pressure (BP) changes were measured using Finapress in children and pulse transit time (PTT) in infants and newborns.

Main Results:

• Basal systolic BP was lower and pulse transit time (PTT) was higher in the prone position compared to the supine position.
• Increases in systolic BP and decreases in PTT following auditory stimulation were smaller in the prone position.
• These findings were consistent during cortical arousals, irrespective of sleep stage.

Conclusions:

• Infants and children sleeping in the prone position exhibit lower basal BP and higher PTT compared to the supine position.
• The reduced cardiovascular response to auditory stimuli in the prone position may indicate an elevated arousal threshold.
• These findings suggest that altered autonomic responses in the prone position could be a contributing factor to increased arousal thresholds.