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Polygraphic investigation of 24-h waking distribution in infants
F Giganti1, I Fagioli, G Ficca
1Department of Psychology, University of Florence, Via San Niccolò 93, 50125, Florence, Italy.
Insights
Infants show increased evening wakefulness, suggesting a developmental "forbidden zone" for sleep similar to adults. This period, typically between 5 PM and 8 PM, is characterized by specific behavioral and physiological cues.
Area of Science:
- Developmental Pediatrics
- Sleep Science
- Neuroscience
Background:
- Adult sleep patterns exhibit an "evening forbidden zone" for sleep.
- The existence and timing of such a zone in early human development remain largely uncharacterized.
Purpose of the Study:
- To investigate the prevalence and characteristics of evening wakefulness in infants.
- To determine if a developmental equivalent of the adult "forbidden zone" for sleep exists in infants.
Main Methods:
- Longitudinal 24-hour recordings in 12 infants (2 weeks to 11 months 3 weeks old).
- Multichannel physiological data acquisition: Electroencephalography (EEG), Electrooculography (EOG), Electromyography (EMG), respiration, and electrocardiography (ECG).
- Behavioral observations combined with electrophysiological data to define four distinct states, including wakefulness.
Main Results:
- Infants under 12.5 months displayed significantly higher wakefulness between 5 PM and 8 PM (17:00–20:00).
- Older infants in the study exhibited uniformly high wakefulness throughout daytime hours.
- Wakefulness was characterized by open eyes, eye movements, body movements, and irregular respiration.
Conclusions:
- The findings support the hypothesis of a developmental "forbidden zone" for sleep in infants.
- This period of increased evening wakefulness in infants aligns temporally with the adult "forbidden zone".
- Suggests a conserved biological mechanism influencing sleep onset timing across development.
Abstract:
An evening forbidden zone for sleep has been shown for adults. This research was aimed to ascertain the prevalence of waking in the evening in early development. Twelve infants, aged between 2 weeks and 11 months 3 weeks, were each recorded once over a 24-h period. Recordings included EEG, EOG, EMG, respiration, ECG, and behavioural observation. Four states were defined by combining behavioural and electrophysiological data. Wakefulness was defined by the presence of eyes open, eye movements and additionally body movements, and irregular respiration. In infants younger than 12 months and a half, a greater amount of wakefulness was observed in the time interval between 17 and 20. Older infants show uniform high amount of wakefulness during daytime. Our data corroborate the hypothesis that evening hours are those most frequently characterised by the behavioural waking state, suggesting that a forbidden zone for sleep exists in development and that its time placement corresponds to the one observed in the adult.