The Development of Circadian Rhythms in Human Infants

Sleep parameters were recorded as means for the group. Changes in sleep were related
to maturation of infant physiology as determined by achievement of adult pattern of
core body temperature during night time sleep.
7.2 Description of mean sleep parameters for 35
infants
On average infants were put to bed at around 20:42 hours according to sleep diary.
This was confirmed by actigraphy with sleep start at 20:40 in the evening. The latest
sleep start for an individual baby was 00:19 by actigraphy. Mothers recorded on sleep
diaries that infants woke at a mean time of 07:20 hours. On average sleep ended at
07:16 in the morning. The earliest sleep end for an individual infant was at 03:55
hours by actigraphy.
On average the infants slept for 7.18 (SD =1.20) hours per night, with minimum
duration 3.45 hours and maximum 10.52 hours. During the period from sleep onset to
the end of night time sleep 2 hours 3 minutes were spent awake (range 3 minutes to 5
hours 9 minute; SD = 1 hour 7 minutes). Average sleep latency (SD) was 11 (15)
minutes (range 0 minutes to 1 hour 23 minutes). The infants spent 78.3% of their time
in bed actually asleep during the night time period. Sleep efficiency (SD) averaged at
75.3 (10.98) %. The most sleep efficient infants had a score of 97.8% with the
minimum being 49.4%.
The mean fragmentation index (SD) was 74.85 (35.42) with the score ranging between
22.3 and 201.4. The infant mean activity score (SD) during periods of wakefulness
overnight was 32.69 (21.39). The minimum activity score was 2.89 and maximum
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