The experimental sleep protocol and sample are detailed elsewhere [4
] and were approved by the local Institutional Review Board. Twenty 13.9–16.9 year-old participants were recruited via mass e-mail and screened via parent-report for sleep disorders (in part using the Child Sleep Habits Questionnaire [6
]), a history of neurological illness or injury, and current illness, injury or medication known to impact sleep or daytime functioning. Throughout the 3-week experiment, prescribed wake time was held constant at the time each participant reported that they would need to arise to attend an 8:30 am meeting. During the baseline
week, participants self-selected their bedtimes. During the next two weeks, bedtimes were modified to create two conditions (order counterbalanced): sleep deprivation
(SD; Monday-Friday nights limited to 6.5 hours in bed) and healthy duration
(HD; 10 hours in bed Monday-Friday nights). Saturday and Sunday nights were “washout” periods, during which bedtime was participant-selected. Participants slept at home, monitored via actigraphy and sleep diary. Participants also used a daily diary to record caffeine intake and napping, though both were quite limited [4
]. Participants were reimbursed $50 weekly.
Between 09:00 and 11:30 on the Saturday mornings at the end of each experimental week, participants were assessed in a simulated classroom analogous to that used in younger children to assess attention [7
]. Participants were seated behind a table and viewed 30-minute educational films presented on a 19-inch television ~6 feet away. The two films, presented one per week in counterbalanced order, were selected from The Western Tradition
series (Annenberg Foundation, Washington, DC) based on their developmentally-appropriate content. Afterwards, participants completed related 12-item multiple-choice quizzes. Twelve participants experienced the simulated classroom in groups of 2–3, while eight did so individually while undergoing video and electroencephalography (EEG) monitoring. A limited montage of EEG leads was secured to the scalps of these eight prior to the films. During the films, video of each participant was recorded, and linked EEG data was amplified and digitized at a rate of 256 data points per second (Hz).
There were three primary outcomes. Quiz performance
was computed as the number of items correct. The two quizzes correlated moderately, r
= .53, and had equivalent means and variance within each condition. Inattentive behavior
, operationalized as occurrences in which the participant looked away from the television for ≥ 3 consecutive seconds, was coded by a condition-blind rater in 30-second epochs. Secondarily, the rater coded sleepy behaviors, including yawning, eye rubbing, and eyes closed or head on the table for ≥3 consecutive seconds. Tonic arousal
was operationalized by spectral power in the relatively slow theta range (4–7 Hz) in the C3
EEG channel commonly used while coding sleep/wake data. Spectral power was computed via Fourier transformation after manual screening for artifacts, with higher theta power reflecting lower arousal [5
], and log-transformed to approximate the Gaussian distribution.