Columnar analysis of sleep electroencephalogram.

During sleep, different rhythms appear in the electroencephalogram. The alpha rhythm was recently suggested to be the result when the excitability of the cerebral cortex is increased and decreased in order to keep the number of highly active columns within reasonable limits. It was found that the number most often is kept between four and five when awake. If the number is kept within other limits, the result will be different electroencephalogram rhythms. It is proposed that this is the explanation of the various rhythms during sleep.