Temporal sequencing in sleep and waking states during the first 6 months of life

Abstract

All-night polygraphic recordings of 25 normal infants were carried out to describe the early development of sleep-waking-state sequencing. Each minute of the 12-h recordings was coded into quiet sleep, active sleep, or waking states. These data were then transformed into a binary series and subjected to spectral analysis using the fast Fourier transform for determination of periodicity of each state. Spectral estimates of sleep- and waking-state periodicities displayed a high variance early in life, but by 3 to 4 months of age, there was a principal rhythm approximating 1 cycle/h in the active and quiet sleep states. The average frequency for the quiet and active sleep states increased significantly from 0.87 to 1.07 cycles/h during this 6-month period. These data offer evidence that the establishment of the periodic organization of sleep states requires 4 months to develop in the normal infant.