Subjective and Objective Daytime Sleepiness in Schoolchildren and Adolescents: Results of a Community-Based Study

Study Questions:

Is the Pupillographic Sleepiness Test (PST) an adequate method for assessing daytime sleepiness among schoolchildren and adolescents?


Data for the present study were from an observational, cross-sectional, community-based study. PST recordings were performed in schools (located in Tuebingen, Germany) between November 2008 and February 2009, using two identical PST devices in two appropriate rooms shielded from daylight. Subjects were tested between 9:30 am and 1:00 pm according to a standard operating procedure. Participants were recruited and balanced by age and gender from schools using stratified random sampling. One primary school (first–fourth grade) and one high school (fifth–12th grade) were selected to cover the total age span of schoolchildren. Sleep problems and subjective sleepiness were assessed using parent- and self-reported questionnaires. Objective sleepiness was assessed in schools under standardized conditions by using the PST and by calculating the natural logarithm of the pupillary unrest index.


Of all children whose parents provided consent (N = 251), 168 were randomly selected and 163 (82 boys; age range, 6.6–17.8 years) fulfilled the inclusion criteria for age (ages, 6–17 years). Age and sleep problems were predictors of subjective sleepiness. Nine PST recordings (5.5%) were excluded due to artifacts (feasibility, 94%). Gender, sleep problems, and sleep duration were predictors of objective sleepiness. Compared to adults (age range, 20–60 years), the pupillary unrest index was higher in children (mean ± standard deviation [SD], 1.5 ± 0.4 vs. 2.0 ± 0.4; p < 0.001) and showed significant gender differences. There was no agreement between measures of subjective sleepiness and the pupillary unrest index (r < 0.3). After excluding children with sleep problems, preliminary reference values (mean ± SD) for the pupillary unrest index were 2.01 ± 0.43 for boys and 1.93 ± 0.43 for girls, respectively.


The investigators concluded that the PST is a feasible method in schoolchildren and adolescents. Sleep problems are predictors of both subjective and objective sleepiness; there is no agreement between the latter. Results of the PST are influenced by sleep duration, and specific pediatric gender-stratified reference values are definitively needed.


These data suggest that PST is a test of sleepiness, which is feasible in children. Furthering our understanding of sleep characteristics in children has important clinical and public health implications for overall health and aging. Further research in larger cohorts of children is warranted.

Clinical Topics: Heart Failure and Cardiomyopathies, Sleep Apnea

Keywords: Parents, Cross-Sectional Studies, Reference Values, Germany, Questionnaires, Sleep Apnea Syndromes

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