Study of cyclic structure of daytime sleep in normal infants aged 2 to 12 months.
Polygraphic records of the whole duration of the second daytime sleep period have been performed in two groups of infants: 1st group (13 infants)--aged 2, 3, 4, 5 and 6 months (a total of 65 polygrams), and 2nd group (14 infants)--aged 6, 9 and 12 months (a total of 42 polygrams). The analysis of the structure of the sleep period as a whole reveals that with increasing of the age the delta-wave stage (DS) of the QS (determined by defined polygraphic parameters) increases, while the paradoxical phase of sleep (PS) decreases, this change being more pronounced during the first six months than during the second ones of the first year of the life. During the second six months the change is significant for DS duration and slightly expressed for PS duration. By analysis of the consecutive sleep cycles, composing one sleep period, it is found that: (a) during infancy the first cycle has a relatively stable duration, slight change of the ratio between DS% and PS%; after the age of 6 months its PS is greater and DS is smaller than the respective values of the second cycle; (b) with increasing of the age the second cycle tends to become shorter than the first one, this phenomenon being better manifested during the second six months of the first year; the ratio between DS% and PS% reveals much greater age-dependent changes than in the first cycle. It is concluded that during the infancy the described general tendency of the sleep structure development, restricted to one daytime sleep period, is reflecting mainly the changes in the structure of the second cycle of this period.
D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D010507:Periodicity; D012890:Sleep / Q000502:physiology*