Respiration During the First Six Months of Life in Normal Infants: II. The Emergence of a Circadian Pattern

Abstract

The objective of the present study was to investigate the emergence of circadian patterns in respiratory rates. Twenty-five neurologically normal infants were monitored for 12-hours during the first week of life and at one, two, three, four and six months of age. Each minute of the recordings of EEG, eye movements, somatic activity, respiration, ECG and temperature was coded into Active sleep (AS), Quiet sleep (QS), Indeterminate (IN) and Awake (AW). The night was divided into four equal intervals and a computer program calculated the mean respiratory rate for each interval as a function of state and age. During the first week of life group means of respiratory rates increased linearly with each interval in all states. A circadian pattern with lowered respiratory rates between 10:00 p.m. and 1:00 a.m. emerged at different ages in different sleep states. This pattern was first seen at one month of age in AS and IN, and at three months in QS. It was also observed in AW at three months of age, suggesting that the circadian rhythm is not solely an expression of the sleep wakefulness cycle. Feeding patterns contributed to but did not explain these observations.

Frequency of Obstructive and Mixed Sleep Apneas in 1,023 Infants

“…1,2,[8][9][10][11]14 Most previous studies were however done on small groups of infants and some studies did not differentiate obstructive from mixed events. 4,8,10,11,14 In the present report, obstructive apneas were almost twice as frequently found than mixed apneas.…”

The Emergence of a Circadian Pattern in Respiratory Rates: Comparison between Control Infants and Subsequent Siblings of SIDS

“…In a previous report (20), we emphasized two observations in control infants. First, a circadian pattern appeared in AS and IN respiratory rates during the first month of life, two months before the appearance of a similar pattern in QS.…”

“…In a previous report, we demonstrated the emergence of what seemed to be a circadian pattern in respiratory rates during the first six months of life in normal full-term infants (20). This pattern was characterized by decreased respiratory rates between approximately 10:00 P.M. and 4:00 A.M., as wmpared to either before or after that time.…”

Analysis of respiratory rate and the respiratory cycle in infants and children using an optical sensor

“…Some smdies have found no gender differences in RR (Tepper et al, 1986;Morley et al, 1990;Rusconi et al, 1994;Yau and Fang, 1994). In contrast, Hoppenbrouwers et al (1979) found the mean RR in infant girls to be 4.7 to 5.9 bpm less than in boys. Respiratory rate is increased in awake and calm children compared to sleeping children (Morley et al, 1990;Rusconi et aL, 1994).…”

“…Hoppenbrouwers et aL (1979) demonstrated the emergence of a circadian pattem in RRs in fullterm infants aged up to six months. RRs decreased between 10:00 PM and 4:00 AM.…”