Non-REM Sleep Instability in Children With Primary Monosymptomatic Sleep Enuresis

Sleep enuresis is one of the most common sleep disturbances in childhood. Parental perception of deeper sleep in children with sleep enuresis is not confirmed by objective studies. However, evidence of disturbed sleep has been demonstrated by questionnaire, actigraphy, and polysomnographic studies, but no neurophysiological correlation with low arousability has been found. The goal of this study was to analyze the sleep microstructure of children with sleep enuresis using cyclic alternating pattern (CAP) analysis.

Forty-nine children were recruited, 27 with enuresis (19 males and 8 females, mean age 9.78 years, 2.52 standard deviation) and 22 normal control patients (11 males and 11 females, mean age 10.7 years, 3.43 standard deviation); all subjects underwent clinical evaluation followed by a full-night polysomnographic recording. Psychiatric, neurological, respiratory, and renal diseases were excluded.

No differences in sex, age, and apnea-hypopnea index were noted in the patients with enuresis and the control patients. Sleep stage architecture in children with sleep enuresis showed a decrease in percentage of stage N3 sleep. CAP analysis showed an increase in CAP rate in stage N3 sleep and in phase A1 index during stage N3 sleep in the sleep enuresis group, but also a significant reduction of A2% and A3% and of phases A2 and A3 indexes, supporting the concept of decreased arousability in patients with sleep enuresis. The decrease of phase A2 and A3 indexes in our patients might reflect the impaired arousal threshold of children with sleep enuresis. Sleep fragmentation might result in a compensatory increase of slow wave activity (indicated by the increase of CAP rate in stage N3 sleep) and may explain the higher arousal threshold (indicated by a decrease of phase A2 and A3 indexes) linked to an increased sleep pressure.

The findings of this study indicate the presence of a significant disruption of sleep microstructure (CAP) in children with sleep enuresis, supporting the hypothesis of a higher arousal threshold.