Heart rate changes during sleep in normal two-month-old infants

Area of Science:

• Pediatrics
• Sleep Medicine
• Cardiology

Background:

• Heart rate regulation in infants is crucial for development.
• Sleep states significantly influence physiological parameters in neonates.
• Understanding diurnal variations in infant heart rate is important for assessing cardiovascular health.

Purpose of the Study:

• To investigate diurnal variations in heart rate during active sleep (AS) and quiet sleep (QS) in normal two-month-old infants.
• To examine the impact of sleep cycles, intrasleep awakenings, and periodic breathing on infant heart rate.
• To explore the correlation between respiratory and heart rates during sleep.

Main Methods:

• Polygraphic recordings were conducted on 35 normal two-month-old infants during both nighttime and daytime sleep.
• Heart rates were calculated every minute, categorized by sleep state (AS and QS).
• Statistical analyses were performed to compare heart rates across different conditions and correlate with respiratory rates.

Main Results:

• Mean heart rates were significantly lower during nighttime sleep compared to daytime sleep (P < 0.0001) for both AS and QS.
• Heart rates exhibited minimal values in the middle of sleep recordings, with some statistically significant differences noted, particularly in QS.
• Intrasleep awakenings caused a marked increase in heart rate, especially when infants were fed post-awakening. Infants with periodic breathing showed lower mean heart rates, though not statistically significant.
• A statistically significant correlation was observed between concurrent changes in respiratory and heart rates during sleep.

Conclusions:

• Nighttime sleep is associated with lower heart rates in infants compared to daytime sleep.
• Sleep state, sleep cycle, and external stimuli like feeding influence infant heart rate patterns.
• Heart rate and respiratory rate exhibit synchronized changes during infant sleep, suggesting a coordinated physiological regulation.