Insomnia presents an increasing and significant health issue in paediatric population. As the problem had grown over past decade, it became recognised by the specialists dealing with children and adolescents. In a recent study American Academy of Child and Adolescent Psychiatry members were asked about their experience with patients complaining about sleep disturbances. Doctors reported that sleep was a problem for 1/3 of their patients out of which 1/4 required pharmacotherapy [1]. Multiple studies concerning adults confirmed significance of healthy sleep in optimal cognitive, emotional, social and biological functioning. Adequate sleep is important in prophylaxis of many chronic diseases such as obesity, diabetes, hypertension, myocardial infarction, stroke [2]. Due to increasing prevalence of insomnia in children and adolescents growing attention is paid to its short and long term consequences in this group. This review summarises available data on chronic insomnia prevalence and its consequences in population under 18 years old.