The invention relates to a method for preparing a sulphoxide compound of formula (I) either as a single enantiomer or in an enantiomerically enriched form, comprising the steps of: a) contacting a pro-chiral sulphide of formula (II) with a metal chiral complex, a base and an oxidizing agent in an organic solvent; and optionally b) isolating the obtained sulphoxide of formula (I); ##STR00001## wherein n, Y, R.sub.1, R.sub.1a, R.sub.2 and R.sub.2a are as defined herein.

The invention relates to a process for the preparation of crystalline forms of the optical enantiomers of modafinil, comprising stages comprising: i) dissolving one of the optical enantiomers of modafinil in a solvent other than ethanol, ii) crystallising the modafinil enantiomer, iii) recovering the crystalline form of the modafinil enantiomer so obtained. The invention also relates to a process for the preparation of the optical enantiomers of modafinil.

Modafinil is effective in improving symptoms of eating disorders or in stimulating appetite.

Modafinil is effective in improving symptoms of attention deficit hyperactivity disorder and symptoms of multiple sclerosis fatigue. The administration of modafinil is also shown to activate the tuberomamillary neurons of the posterior hypothalamus, and thus exhibits activity in an area of the brain associated with normal wakefulness functions.

Modafinil is effective in improving symptoms of attention deficit hyperactivity disorder and symptoms of multiple sclerosis fatigue. The administration of modafinil is also shown to activate the tuberomamillary neurons of the posterior hypothalamus, and thus exhibits activity in an area of the brain associated with normal wakefulness functions.

Modafinil is effective in improving symptoms of attention deficit hyperactivity disorder and symptoms of multiple sclerosis fatigue. The administration of modafinil is also shown to activate the tuberomamillary neurons of the posterior hypothalamus, and thus exhibits activity in an area of the brain associated with normal wakefulness functions.