Phase 1: before 1952

I have designated the first phase, to some extent with tongue in cheek, as “prehistoric”. This reflects the relative lack of scientific experimentation involving sleep over the first half of the 20th century and before. The subject of dreams and dream interpretation probably received the most attention. A great deal of the early sleep literature reported observations on sleep habits and sleep characteristics in the service of comparing and contrasting the data reciprocally to data describing the waking state. During this “prehistoric” period nearly every biomedical scientist assumed that sleep occurred when sensory stimulation continuously bombarding the brain during the day was rendered insufficient to maintain a waking level of brain activity by the occurrence of the darkness and silence of night.

It seems reasonable that this perspective, often called the “passive process theory”, would have made the study of sleep seem relatively uninteresting. The notion that sleep was the brain “turned off” led to the erroneous conclusion that sleep could be regarded as an entirely homogenous state, and that a single observation could be generalised to the entire sleep period. Finally, there was no tradition of staying up at night to carry out scientific research except, of course, for astronomy.

There are some “prehistoric” scientific landmarks that are worth noting but which occurred far too early …