Development of body temperature rhythm: 6 years follow up of three cases.

The present study was conducted to evaluate longitudinally the relationship between phase of temperature rhythm and sleep habits. Sleep-logs were recorded from three children for 3 weeks during school term and 1 week before the experiment, and oral temperature was recorded for 2 consecutive days during summer vacations for 6 years. Although previous studies have reported that phase of temperature rhythm was established by 5 years old, phase delay of temperature was found in all subjects even after 5 years old. These results suggest that the establishment of temperature phase is after 5 years old.