The Development of Circadian Rhythms in Human Infants

Heller, 2003). Other studies have shown an increase in quiet sleep with age, with no
change in the percentage of active sleep rather than a decrease, in both term and
premature infants (Navelet et al., 1982, Mirmiran et al,. 2003).
Mirmiran suggested that there is a possibility that sleep is controlled by a mechanism
which is inherent to the infant and that the timing of sleep consolidation and
maturation is not as significantly affected by factors such as prematurity as might be
expected (Mirmiran et al., 2003).
Several studies pin point the timing of the change in sleep from immature to mature
patterns to occur at around 3 to 4 months of age. There are several ways sleep
maturation can be mapped. One way is to document the number of REM sleep onset
periods. In a maturing infant these decrease with age (Coons & Guilleminault, 1984).
Another method used to track changes in sleep is to determine the age when sleep
consolidation occurs, i.e. when night time sleep exceeds day time sleep (Glotzbach et
al., 1995, Ariagno et al., 1997, Mirmiran & Ariagno, 2000).
Mirmiran demonstrated that at 36 weeks (corrected gestational age); infants spent a
large proportion of time during both day and night asleep (65% of their day sleeping
and 71% of the night period asleep). By 3 months of age, daytime sleep had fallen to
significantly lower levels (as low as 18%) while night time sleep remained relatively
unchanged at 65% (Mirmiran & Ariagno, 2000).
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