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BackgroundEvidence is growing that sleep problems in adolescents are significant impediments to learning and negatively affect behaviour, attainment of social competence and quality of life. The objectives of the study were to determine the level of sleepiness among students in high school, to identify factors to explain it, and to determine the association between sleepiness and performance in both academic and extracurricular activitiesMethodsA cross-sectional survey of 2201 high school students in the Hamilton Wentworth District School Board and the Near North District School Board in Ontario was conducted in 1998/9. A similar survey was done three years later involving 1034 students in the Grand Erie District School Board in the same Province. The Epworth Sleepiness Scale (ESS) was used to measure sleepiness and we also assessed the reliability of this tool for this population. Descriptive analysis of the cohort and information on various measures of performance and demographic data were included. Regression analysis, using the generalised estimating equation (GEE), was utilized to investigate factors associated with risk of sleepiness (ESS>10).ResultsSeventy per cent of the students had less than 8.5 hours weeknight sleep. Bedtime habits such as a consistent bedtime routine, staying up late or drinking caffeinated beverages before bed were statistically significantly associated with ESS, as were weeknight sleep quantity and gender. As ESS increased there was an increase in the proportion of students who felt their grades had dropped because of sleepiness, were late for school, were often extremely sleepy at school, and were involved in fewer extracurricular activities. These performance measures were statistically significantly associated with ESS. Twenty-three percent of the students felt their grades had dropped because of sleepiness. Most students (58–68%) reported that they were "really sleepy" between 8 and 10 A.M.ConclusionSleep deprivation and excessive daytime sleepiness were common in two samples of Ontario high school students and were associated with a decrease in academic achievement and extracurricular activity. There is a need to increase awareness of this problem in the education and health communities and to translate knowledge already available to strategies to address it.

Behavioral, event-related potential (ERP), and EEG measures were obtained to describe more fully the relationship between brain activity and arousal level during the process of falling asleep. In addition to standard polysomnographic measures, tones were presented at random intervals throughout two nights to each of nine subjects. Subjects were instructed to respond to the tones whenever they heard them. Initial sleep onset was disrupted five times following zero through four successive response failures. Sampling of EEG was initiated 5 s prior to tone onset (EEG analyses) and continued for 5 s following tone onset (ERP data). With EEG ordered as a function of response rate, significant increases in power were found across all standard frequency bands for the pretone data at sleep onset. Significant changes in amplitude were related to decreasing responsivity for all late ERP components except P2. Inasmuch as virtually all EEG frequencies and ERP components were strongly influenced by momentary changes in arousal, arousal must be considered a (possibly the) primary determinant of the characteristics of the overall electrical output of the brain. Response cessation coupled with sharp increases in EEG synchronization mark the point of sleep onset.

Reaction time (RT), a behavioral measure of arousal, was used to examine standard criteria (Rechtschaffen & Kales, 1968) for assessing sleep onset (SO) and the sensitivity of changes in respiratory patterns at SO. Following 24 hrs without sleep, RT, respiratory, and EEG measures were used to study SO in 12 subjects. Sleep deprivation (SD) permitted multiple examinations of SO in 2 daytime testing periods. Strong relationships between RT and EEG‐based measures of SO serve to confirm the distinction between wakefulness and stage 1 sleep, and moderate to weak correlations between RT and respiratory indices describe the usefulness of the latter. Behavioral, respiratory and EEG assessments of the shift from wakefulness to sleep were observed to be orderly and rapid in these SD volunteers, suggesting that the detection of SO could be sharpened by adding behavioral and respiratory measures to the usual EEG criteria. The close temporal correspondence among these changes has interesting implications for sleep/waking mechanisms.