Compared with darkness, exposure to red light boosted alertness: The EEGs showed a significant reduction in brain-wave activity associated with sleepiness after five minutes.
In earlier experiments, designed to replicate normal learning, Dr Tononi found that the part of the brain showing most slow-wave activity during sleep was the same as the part that had been activated during the experiment.
Functional-imaging studies of the brain have revealed another tantalizing clue: During the aura phase, a wave of electrical activity sweeps over the outer, furrowed layer of the brain known as the cortex, at a pace of 2 to 3 millimeters per minute.