Agents for improving sleep

A chemical compound having the formula the pharmaceutically acceptable acid addition salts and the stereochemically isomeric forms thereof, R and R each independently are hydrogen or C1-6alkyl; X is C1-6alkyl, hydroxyC1-6alkyl, C1-6alkyloxyC1-6alkyl, aminocarbonyl, mono- and di(C1-6alkyl)aminocarbonyl, carboxyl, C1-6alkyloxycarbonyl, (aminocarbonyl)C1-6alkyl, Ämono- and di(C1-6alkyl)aminocarbonylÜC1-6alkyl, carboxylC1-6alkyl, (C1-6alkyloxycarbonyl)C1-6alkyl or (hydroxyC1-6alkyl)aminocarboxyl; m is 1 or 2; n is 1 to 4; Ar is optionally substituted phenyl; optionally substituted pyridinyl; optionally substituted pyrazolyl; or a radical of formula Q' is arylethyl, arylethenyl, aryloxymethyl, diarylmethoxy, 2,2-diarylethenyl, diarylmethylcarbonyl, arylcarbonylmethyl, mono- and diarylaminocarbonyl, diarylethyl or arylaminomethyl. Process for preparing said compounds and pharmaceutical compositions comprising them are also disclosed.