The purpose of this study is to estimated prevalence of obstructive sleep apnea (OSA) in 4-8 year old children. To date, most studies estimating prevalence of sleep apnea in young children are based on utilizing subjective questionnaires. The few studies that have utilized objective sleep measures have tested only those children suspected of sleep apnea based on subjective questionnaires, finding prevalence in the range of 1-13%. Untreated OSA is associated with significant morbidities in children, affecting their behavior, cognitive development, cardiovascular-and cardio metabolic health, endocrine and immune function. Better understanding of prevalence of sleep apnea in young children should be beneficial. This study will help to understand the prevalence of sleep apnea in each age-group of children 4-8 years of age and whether certain groups, such as children with obesity or asthma have higher prevalence and/or more severe disease.

The primary objective of this study is to get better understanding of prevalence and severity of sleep apnea in young children using objective sleep measures for all participants.

The study is a population-based, observational study of 4-8 year old children located in Akureyri, Iceland. All parents in this geographical area will be invited for their child/children to participate in the study.

Parents of all participating children will be asked to answer questionnaires to assess general health, sleep habits, behavior and quality of life and then measure their sleep for five consecutive nights with a home based sleep test.

Inclusion Criteria:

• Children 4-8-years old

Exclusion Criteria:

• Children with atrial fibrillation or ventricular trigemini

All children in a pre-specified geographical area 4-8 years of age