From "A Wearable Sensor for Unobtrusive, Long-term Assessment of Electrodermal Activity" (by Poh, M.Z., Swenson, N.C., Picard, R.W. in IEEE Transactions on Biomedical Engineering, vol.57, no.5), a chart showing a single student's electrodermal activity over the course of a week. Note the neural flatlining during classtime. As Joi Ito notes, "Note that the activity is higher during sleep than during class." He also adds, "Obviously, this is just one student and doesn't necessarily generalize."
A week of a student's electrodermal activity (Thanks, Joi!)