History of SleepIf you consider the amount of time we spend sleeping, it is surprising that there has been so little interest by sociologists and historians until the last century. Although researchers have studied and recorded every other part of our evolvement, the mystery of sleep seems to have offered little inspiration in previous centuries.

Some of this neglect may be due to the earlier belief that nothing happens while we sleep – the body is dormant, in a state of repair. Earlier scientific studies mainly concentrated on sleep disturbances and abnormality. Literature and the arts filled the gaps and the mystery of sleep, dreaming and the role of the subconscious have inspired writers artists, poets and musicians throughout history.

Physical Renewal

One of the earliest scientific references to sleep came from Aristotle (c.350 BCE) who referred to sleep as ‘an inhibition of sense perception for conservation’ confirming the view that sleep was a time of physical renewal.

In the early eighteenth century, a French astronomer conducted experiments with plants and discovered ‘biological rhythms’, but it was not until the 1920s that Dr Nathaniel Kleitman started researching circadian rhythms and sleep deprivation.

Sleep research was then well on its way and from 1930 to the present day it has continued to reveal insights into the sleeping mind and our need for sleep.

The development of instruments that were able to measure brain activity enabled researchers to identify the areas of the brain involved in different activities and the various stages of sleep.

REM Sleep

The importance of the thalamus during sleep was discovered by the Swiss physiologist Walter Hess in the 1940s. The thalamus is a symmetrical structure within our brains and part of its function is the regulation of consciousness, sleep and alertness.

In the 1950s Gustav Kramer and Klaus Hoffman conducted research into the ‘biological clock’ and Dr Nathaniel Kleitman discovered Rapid Eye Movement (REM) sleep in the early 1950s. (Find out more about REM here Rapid Eye Movement ) Research then concentrated on the cycles and states of sleep and the involvement of different parts of the brain.

In the 1960s Michel Jouvet looked into Telencephalic Sleep (slow wave sleep) and Rhombencephalic Sleep (paradoxical sleep) demonstrating the two different states of sleep.

During the same decade scientists interested in the influence of circadian rhythms undertook fascinating experiments. In 1962 research in France and Germany set out to eliminate outside factors such as light and sound so that they could study how they body would react without these influences. In 1962 a French scientist lived underground for two months and German researchers studied the effects of sensory deprivation on humans sealed in a laboratory chamber.

Sleep Apnea and Narcolepsy

The study of sleep disturbances was given a boost with the discovery of sleep apnea in 1965. As our knowledge of the brain and the influence of chemicals and hormones on its functioning increases, there is continuing interest in sleep and sleep disturbances.

During the 1990s the growth of internet technology means research can be shared and there is an increase in interest in ideas for improving sleep quality and helping people suffering from sleep disturbances.

In 1999 William Dement writes about the connection between health and sleep and the health consequences of lack of sleep. In the same year, there is a breakthrough in the study of Narcolepsy with the discovery of a gene linked to this serious condition.

Biological Clock

The discovery, also in 1999, that our natural biological clocks may dictate a natural sleep cycle from midnight to 6am and from 2pm to 4pm, confirms the current view that we are not getting enough sleep.

Since then, our knowledge of sleep has increased and with the establishment of specialist ‘sleep centres’, scientists continue to explore the mystery of sleep and its affect on our lives.