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Long term continuously fed infants do not develop heart rate circadian rhythm

Early Human Development
|December 1, 1985
PubMed

Insights

Continuous feeding in infants prevents the natural daily rhythm of heart rate (HR). While behavioral states still affect HR, the typical nighttime decrease is absent in continuously fed infants, indicating disrupted circadian modulation.

Area of Science:

  • Neonatal physiology
  • Circadian rhythms
  • Infant nutrition

Background:

  • Heart rate (HR) exhibits diurnal variations influenced by behavioral states and sleep cycles in infants.
  • The impact of continuous feeding on the development of circadian rhythms in neonatal HR is not fully understood.

Purpose of the Study:

  • To investigate the effect of long-term continuous nutrition on the circadian modulation of heart rate in infants.
  • To compare HR patterns across different behavioral states (waking, quiet sleep, paradoxical sleep) and nycthemeral periods in continuously fed infants versus controls.

Main Methods:

  • HR was monitored in 8 infants receiving continuous feeding from birth.
  • Data were collected across four periods of the nycthemeron (24-hour cycle).
  • HR was analyzed separately for three distinct behavioral states: waking, quiet sleep, and paradoxical sleep, comparing continuously fed infants with a control group.

Main Results:

  • Continuously fed infants did not show significant differences in HR across the four nycthemeral periods for any behavioral state.
  • Control infants exhibited a clear decrease in HR during nighttime periods.
  • Significant differences in HR were observed between behavioral states in both continuously fed infants and controls.

Conclusions:

  • Long-term continuous nutrition in infants inhibits the establishment of circadian modulation of heart rate.
  • While behavioral states continue to influence HR, the typical diurnal rhythm is not developed under continuous feeding regimens.
  • Continuous feeding disrupts the natural entrainment of cardiovascular rhythms to the light-dark cycle.

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