Chronic insomnia of early childhood: Phenotypes and pathophysiology.

This paper aims to review the limitations of the current classification of insomnia of early childhood and propose a new conceptual model allowing a better understanding of its pathophysiology. Our hypothesis is that chronic insomnia of childhood has different phenotypical expressions, associated to different pathophysiological mechanisms. Based on a long-lasting experience in evaluating a very large number of children with specific insomnia symptoms (nocturnal awakenings, difficulty in falling asleep, nocturnal restlessness, early morning awakenings) and on published data, we hypothesize that different phenotypes of insomnia might exist with different therapeutic implications. We describe three phenotypes of insomnia in early childhood: a) insomnia with motor restlessness; b) insomnia characterized without difficulties in falling asleep but with long-lasting early morning awakenings; c) insomnia with multiple night awakenings and falling asleep difficulty. This type of categorization might have important implications for treatment, based on the different hypothetical neurotransmitter dysfunctions. The early identification of a phenotype of insomnia might guide to specific behavioral and/or pharmacological interventions with the aim to prevent chronic insomnia.