As far as the melatonin, don't waste your money on it, because it doesn't do anything for you. You'd get just as good result, giving your child pieces of candy, or anything edible really, and telling them that it'll help them sleep, and if they believe it will, it might, just like melatonin does.
Ultimately, all of the data is stored in columns, and metadata is required to identify the columns that function as multidimensional objects. In Oracle Database, you can define a logical multidimensional model for relational tables using the OLAP Catalog or AWXML, as described in Chapter 5..2 The Relational Implementation of the Model. The relational implementation of the multidimensional data model is typically a star schema, as shown in Figure 2-2, or a snowflake schema.
The measurement model is the part which relates measured variables to latent variables. The structural model is the part that relates latent variables to one another. Statistically, the model is evaluated by comparing two variance/covariance matrices. From the data a sample variance/covariance matrix is calculated.