Development of night time temperature rhythms over the first six months of life

Article Abstract:

A characteristic pattern of body temperature change develops within the first four months of life. Among young infants, body temperature decreases from above 37 degrees Centigrade (C) at bedtime to 36.4 degrees C within the first two hours of sleep, remains low, and rises again before waking. The drop in temperature is associated with sleep, but is greater during nighttime sleep than during daytime sleep. These findings suggest a circadian rhythm, or 24-hour pattern, that may vary somewhat from one infant to another. The fall in body temperature is not affected by the surrounding temperature or the thermal insulation provided by clothing. Hence, the pattern appears to be controlled within the body and maintained by thermoregulation, a physiologic mechanism that automatically controls body temperature. The pattern of temperature change is not present in newborns and probably develops within the first one to two weeks of life. To learn more about this phenomenon, the nighttime rectal temperatures of 49 babies were measured continuously during the first six months of life. It was found that after six weeks the babies' rectal temperatures were significantly higher at bedtime than later during the night. Nighttime body temperatures dropped to 36.5 degrees C by 12 weeks of age, and a consistent pattern of body temperature change was evident in all 16-week-old babies. Specifically, body temperature fell by 0.8 degrees C within the first two hours of sleep, remained low, and increased again one to two hours before awakening. The decrease in body temperature to 36.5 degrees C coincided with a sleeping duration of seven hours. The duration of sleep increased as the baby's rectal temperature decreased with sleep. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Demographic aspects, Body temperature regulation, Circadian rhythms

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Sleeping position and rectal temperature

Article Abstract:

Several reports have suggested a possible association between sleeping in the prone (stomach down) position and a risk of crib death (sudden infant death syndrome, or SIDS). It is thought that babies in this position, especially in warm rooms or when covered warmly, are at risk of overheating. Although babies over three months of age maintain consistent night-time core (deep body) temperatures, it is possible that temperature-elevating factors other than the prone position, such as infections, may be potentiated by the position. To better understand this situation, the disturbed temperature rhythms which follow diphtheria, pertussis and tetanus (DPT) immunization were studied in 137 infants who were sleeping in a variety of conditions. In normal babies aged 12 to 22 weeks, there were no differences in body temperature between those sleeping prone and those sleeping supine (stomach up) or laterally (on their sides). However, among babies covered more heavily who were in rooms over 18 degrees Celsius (about 65 deg F), those who were prone had significantly higher temperatures than those who were supine or lateral. Among normal babies aged six to 12 weeks, there were no significant differences in temperature according to sleeping position. Among normal babies on the night after the first DPT immunization, there were no significant differences. The study shows that babies regulate their temperatures in spite of sleeping positions, even when well wrapped, in warm rooms, and when affected by factors causing mild fevers. (Consumer Summary produced by Reliance Medical Information, Inc.)

Sudden infant death syndrome, Sleep positions

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Disturbed nights and 3-4 month infants: the effects of feeding and thermal environment

Article Abstract:

In addition to their other responsibilities, the parents of 98 babies agreed to take on the task of keeping a diary of their infants' sleeping habits. The purpose of the diaries was to identify feeding and temperature patterns which might contribute to disturbed sleep in three- to four-month olds. Although some studies have indicated that breast fed babies awaken more often at night, the present study found that to be true only within the first four hours of night-time sleep. Overall, the breast fed babies did not awaken more often. However, a significant correlation was found between temperature and waking at night. The body temperature of babies who awakened was greater than that of those who appeared to be asleep. Furthermore, the babies who awakened more often tended to be in warmer rooms and were also more likely to be warmly wrapped. In many cases, it was observed that the babies who woke at night were sweating. A possible explanation for these findings is that the baby must expend a considerable amount of metabolic effort on proper temperature regulation. In a hot room, with warm wraps, the effort may create so much stress that the baby becomes uncomfortable and wakes up. The authors suggest that these effects are probably stronger than those related to breast feeding. A breast feeding mother who wishes to maximize her chances for undisturbed sleep might wish to supplement her child's feeding with a bottle before bedtime, and to use less wrapping in a somewhat cooler room for the sleeping infant. (Consumer Summary produced by Reliance Medical Information, Inc.)

Environmental aspects

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