Original ArticleSubjective and objective daytime sleepiness in schoolchildren and adolescents: results of a community-based study
Introduction
There are a variety of subjective and objective instruments to assess daytime sleepiness in children and young adults [1]. Evaluations usually include some kind of structured sleep history, sleep logs, and sleep questionnaires, as well as objective tests like the multiple sleep latency test (MSLT) [1], [2], [3]. The MSLT is a diagnostic test to measure sleep propensity in the diagnostic workup of narcolepsy and other hypersomnias of central origin [4]. Its use to assess sleepiness is questionable, given the large overlap between normal subjects, with reduced mean sleep latency found in subjects with sleep disorders [4]. Therefore, some authors have questioned its status as a gold standard for the evaluation of daytime sleepiness [5]. Furthermore, it is costly and time consuming, lacks sufficient normative data in pediatric patients, and suffers from motivational influences and the last nap effect [3]. Consequently, a feasible, convenient, and time-saving method that also is less dependent on motivation would be a major improvement.
A possible alternative could be pupillography. More than 40 years ago, Lowenstein et al. [6] first observed characteristic fluctuations in pupil size in sleepy individuals. Meanwhile, the Pupillographic Sleepiness Test (PST) is a standardized, valid, and reliable physiologic test to assess the level of sleepiness in otherwise healthy adults and in those with sleep apnea and narcolepsy [7], [8], [9], [10], [11], [12], [13], [14]. Moreover, it also has been discussed for the laboratory assessment of daytime sleepiness in children [2]. However, the need for cooperation and sitting still as well as keeping fixation stable for several minutes was considered problematic for use in children [2]. In addition, sensitivity was questioned and the lack of validation data in children was emphasized [2]. These factors may be the reasons why there is not yet widespread use of the PST in children.
As part of an interdisciplinary project on daytime sleepiness in schoolchildren and adolescents (i.e. TUPEDS: Tuebingen project on excessive daytime sleepiness in childhood), we aimed to assess the distribution of sleepiness and its main determinants by using parent- and self-reported questionnaires and the PST. Concerning the latter, additional goals were aimed to investigate the feasibility of PST performed in the field, detect its main determining factors, compare PST results to subjective measures of sleepiness, and detect differences to adult reference values.
Section snippets
Study design and subjects
Our study was performed in two regular public schools in Tuebingen, Germany (108 square kilometers; 85,300 inhabitants). One primary school (first–fourth grade) and one high school (fifth–12th grade) were selected to cover the total age span of schoolchildren. Schools were approached following approval by the institutional review board and the regional directorate of education. Detailed study information including a parental and child consent form was distributed by teachers. Using a stratified
Sample and questionnaires
Of all children whose parents provided consent (N = 251), 168 were randomly selected and 163 fulfilled the inclusion criteria for age (ages, 6–17 years). Demographic characteristics for this sample are given in Table 1; descriptive statistics for questionnaire scales are provided in Table 2. The proportion of nonwhites was <5%. Stratification by ethnic group therefore was not appropriate.
Linear regression analysis revealed that all questionnaire scales depended on age (all P < .05) and two scales
Discussion
In our study, we confirmed earlier observations that sleep problems in schoolchildren may be linked to subjective and objective measures of sleepiness [28], [29], [30], [31]. In addition, age and gender were significant predictors for some instruments assessing subjective sleepiness. Initially, we also aimed at proposing reference values for these instruments. However, due to the age dependency of all sleepiness scales and gender dependency of some, our sample size was not large enough to
Limitations
Although the participants in our study were schoolchildren from the community between the ages of 6 and 17 years, we cannot prove the representativeness of our sample. The uncertain representativeness, the small sample size, and the lack of a generally accepted definition prevented us from reporting estimates for the prevalence of daytime sleepiness. If the PUI depends on socioeconomic status, the type of secondary school may be a confounding factor. In Germany, children are streamed to
Conclusions
The PST is feasible in children and adolescents from ages 6 to 17 years and may be a simple screening tool for daytime sleepiness in children. The lnPUI as main parameter of the PST is higher in children compared to adults and depends on gender, which makes specific pediatric gender-stratified reference values necessary. The lnPUI is related to sleep duration in the night before testing and sleep problems, which supports the assumption that pupillary instability does reflect the level of
Funding sources
This project was partly supported by a research grant of the University Hospital Tuebingen (AKF program, grant application number 226-0-0).
Conflict of interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2013.05.014.
Acknowledgments
We thank all the pupils, parents, teachers, and headmasters of the 2 participating schools (primary school “Hechinger Eck”, high school “Carlo-Schmid-Gymnasium”) for their motivating interests, support, and participation in our study. We thank Jutta Diem and Katharina Weible for obtaining questionnaires and pupillographic recordings in schools and Anne Kurtenbach for her native speaker criticism and thorough review of the manuscript.
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These authors contributed equally to this publication.