Influence of ambient temperature on sleep characteristics and autonomic nervous control in healthy infants

Objective: To evaluate the influence of ambient temperature on infant's sleep and cardiorespiratory parameters during sleep. Patients and method: 20 healthy infants with a median age of 11.5 weeks (range 7 to 18 weeks) were recorded polygraphically for one night, They were exposed to 3 different ambient temperatures (20 degrees C-25 degrees C-30 degrees C). Ambient and core temperatures were measured throughout the procedure. Results: influence of ambient temperature was seen in: Respiratory parameters: The frequency of central apneas increased significantly with increasing temperatures in REM sleep, but not in NREM sleep. Heart rate (HR) parameters and HR spectral analysis: Elevation of temperature was characterized by significantly higher basal HR, shorter RR intervals, and lower parasympathetic activity in REM and NREM sleep. Saturation in oxygen: During total sleep time, rise in temperature induced a decrease in basal oxygen saturation. During REM sleep, a greater frequency of oxygen saturation drops was associated with central apneas. Core temperature: With increasing ambient temperature, the rise of rectal temperature was mild. Despite this lack of significant increase, similar results were found when sleep and cardiorespiratory parameters were evaluated according to rectal temperatures. Conclusion: Changes in ambient temperatures associated with mild increases in body temperature significantly modified cardiorespiratory parameters and autonomic controls in healthy infants. The changes associated with increases in temperature were mainly seen during REM sleep.