Information can easily pass the low-level threshold of these neurons, leading to a high transfer ratio. The complexity of the electroencephalogram during conscious waking is high as expressed in a high correlation dimension. Accordingly, the level of information processing is high. Spindles, and alpha waves in humans, mark the transition from wakefulness to sleep. These phenomena are related to drowsiness, associated with a reduction in consciousness.
Drowsiness occurs when cells undergo moderate hyperpolarizations.
Increased inhibitions result in a reduction of afferent information with a lowered transfer ratio. Information processing subsides, which is also expressed in a diminished correlation dimension. Consciousness is further decreased at the onset of slow wave sleep. This sleep is controlled by the medullar reticular formation and is characterized by a high voltage, low frequency electroencephalogram. Slow wave sleep becomes manifest when neurons undergo a further hyperpolarization.