Maturation of spontaneous arousals in healthy infants.
OBJECTIVE
The propensity to arouse from sleep is an integrative part of the sleep structure and can have direct implications in various clinical conditions. This study was conducted to evaluate the maturation of spontaneous arousals during the first year of life in healthy infants.


METHODS
Nineteen infants were studied with nighttime polysomnography on 3 occasions: aged 2 to 3 months, 5 to 6 months, and 8 to 9 months. Ten infants with a median age of 3 weeks were added to the main study to assess the maturation of arousals from birth. The infants were born full-term, were healthy at the time of study, and had no history of apnea. Sleep-state and cardiorespiratory parameters were scored according to recommended criteria. Arousals were differentiated into subcortical activations or cortical arousals, according to the presence of autonomic and/or electroencephalographic changes. Frequencies of subcortical activations and cortical arousals were studied at different ages in both rapid eye movement (REM) and non-rapid eye movement (NREM) sleep.


RESULTS
During sleep time, the frequency of total arousals, cortical arousals, and subcortical activations decreased with age. The maturation of the arousal events differed according to sleep states and types of arousals. With age, cortical arousals increased in REM sleep (P = 0.006) and decreased in NREM sleep (P = 0.01). Subcortical activations decreased with age in REM (P < 0.001) and NREM sleep (P < 0.001).


CONCLUSIONS
During total sleep time, the frequency of cortical arousals and subcortical activations decreased with maturation. However, the maturation process was different between cortical arousals and subcortical activations. This finding suggests a difference in the maturational sequence of the different brain centers regulating arousals.
Montemitro
Enza
E
Department of Paediatric, Sleep Disease Centre, University of Rome La Sapienza, S Andrea Hospital, Rome, Italy.
Franco
Patricia
P
Scaillet
Sonia
S
Kato
Ineko
I
Groswasser
Jose
J
Villa
Maria Pia
MP
Kahn
Andre
A
Sastre
Jean-Pierre
JP
Ecochard
René
R
Thiriez
Gerard
G
Lin
Jian-Sheng
JS
D001143:Arousal / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007223:Infant; D018730:Infant Behavior / Q000502:physiology*; D007231:Infant, Newborn; D008297:Male; D017286:Polysomnography; D012016:Reference Values; D012890:Sleep / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology