The Sleep-EVAL Expert System

Sleep-EVAL, an artificial intelligent computer program, is an Expert System for evaluation and diagnosis of Sleep and Mental Disorders in general and clinical populations.


An expert system is a computer program conceived to simulate some forms of human reasoning (by the intermediary of an inference engine) and capable to manage an important quantity of specialized knowledge.
These capacities for reasoning and management allow the system to target a small number of relevant hypotheses in the mass of potential diagnoses and being able to find a satisfactory diagnostic conclusion.
Two characteristics of the expert system are essential to accomplish this task:

  • the aptitude to process an important mass of specialized knowledge and
  • the aptitude to simulate the human reasoning (in an imperfect manner).


There are many well known advantages to using computerized tools and expert systems:

  • reduction of missing data,
  • better collection of data,
  • no omission of questions,
  • no data transcription,
  • broader coverage of diagnoses, etc...

Even if some computerized tools possess some diagnostic trees, the term "computerized tools" is not synonymous with "expert systems".
Over their apparent similarities, they are radically different in terms of both conception and capabilities.
Indeed, the apparent reasoning process in computerized tools is only an artifice: The diagnostic trees are predetermined and the software only goes from one node to another without attempting to look for other paths.
Expert systems are making their decision during the interview, looking for the optimal way to reach their conclusions: to make a diagnosis.

Obviously, some limits remain.
Both types of instruments do not possess the richness of the human language and some may complain of a inflexibility in wording.
They cannot analyze non-verbal information such as a lack of hygiene, etc., nor detect a contradiction between a verbal answer and behavioral cues.
Most computerized tools are unable to analyze temporal information, for example, to determine which symptom appeared first unless, like Sleep-EVAL, they have a mathematical preprocessor able to make this type of analysis.


There are two ways to proceed in order to improve epidemiological studies using an expert system like Sleep-EVAL:
- The first lies in the improvement of the questionnaire. This can be accomplished by increasing the quality of data collected by allowing fuzzy and uncertain answers.
- The second way introduces a sharper knowledge of the elements belonging to a diagnosis. This can be done by calculating the relative weight of those elements in the diagnosis of a given pathology. Quality, frequency, intensity are all elements that provide indication on the strength of the associative links between the different criteria and the diagnosis.


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