Related Experiment Video
Updated: Aug 15, 2026
EEG Mu Rhythm in Typical and Atypical Development
Published on: April 9, 2014
Infradian rhythmicity in sleep/wake ratio in developing infants
1GMDRB, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, São Paulo, São Paulo, Brazil. diambra@if.sc.usp.br
Insights
Newborns exhibit infradian rhythms, or monthly cycles, in their sleep/wake patterns. These findings suggest internal stimuli may regulate infant sleep and wake durations beyond daily cycles.
Area of Science:
- Chronobiology
- Developmental Pediatrics
Background:
- Existing research extensively documents ultradian and circadian rhythms in newborns.
- Infradian periodicities in early human development are less understood, with limited prior reports.
Purpose of the Study:
- To investigate infradian rhythms in the sleep/wake cycle of healthy newborns.
- To analyze monthly range periodicities in infant sleep patterns over 24 weeks.
Main Methods:
- Utilized sleep diary records from four healthy newborns, converting data into binary time series (sleep -1, wake 1).
- Calculated cumulative sleep/wake time and derived the sleep/wake ratio (SWR) via average slope.
- Applied Fourier periodogram analysis to the SWR time course to identify periodicities.
Main Results:
- Observed significant individual variations in SWR patterns among infants.
- Two infants displayed a linear SWR decay, indicating more sleep than wake time.
- The other two infants showed SWR oscillations near zero.
- Robust infradian oscillations (monthly range) were detected in all infants via Fourier periodogram analysis.
Conclusions:
- Sleep and wake durations in newborns appear to be modulated by internal stimuli operating on infradian timescales.
- This study highlights the presence of monthly rhythms in infant sleep/wake cycles, expanding our understanding of developmental chronobiology.
Abstract:
Although there are several reports on ultradian and circadian rhythms in newborns, we found only one report in which infradian periodicities are described for heart-rate measurements in the early stages of human development. Here, we report infradian rhythms in the monthly range in the sleep/wake cycle of four infants studied along 24 consecutive weeks. Our procedure was applied to sleep diary records from four healthy newborns. The data were arranged in binary time series representing sleep (-1) or wake (1) states. These time series were integrated in order to obtain the cumulative sleep/wake time. A measure of the sleep/wake ratio (SWR) was obtained by computing the average slope of the cumulative sleep/wake time. To extract periodicities we applied the Fourier periodogram to the temporal course of the SWR. We found a notorious difference in the SWR pattern among infants. In two infants the SWR showed a marked linear decay, spending more time asleep than awake, while in the two other infants oscillated near zero. We found robust oscillations in all children. In all cases the Fourier periodogram results present significant power in the infradian range. From these results, we suggest that sleep and wake durations are probably modulated by some internal stimuli.
Related Concept Videos
02:19Circadian Rhythms and Gene Regulation
01:24Sleep-Wake Cycles
NREM Sleep
NREM sleep comprises four progressive stages that seamlessly merge:
01:22Stages of Sleep
Before sleep begins, in wakefulness, the brain exhibits primarily beta waves, which are high in frequency and low in amplitude, indicating alertness...