This invention relates to N-aroyl cyclic amine derivatives and their use as orexin antagonists wherein: Y represents a bond, oxygen, or a group (CH2)n, wherein n represents 1, 2 or 3; m represents 1, 2, or 3; p represents ) or 1; X is NR, wherein R is H or (C1-4)alkyl; Ar1 is aryl, or a mono or bicyclic heteroaryl group containing up to 3 heteroatoms selected from N, O and S; any of which may be optionally substituted; A2 represents phenyl or a 5- or 6-membered heterocyclyl group containing up to 3 heteroatoms selected from N, O and S, wherein the phenyl or heterocyclyl group is substituted by R1 and further optional substituents; or Ar2 represents an optionally substituted bicyclic aromatic or bicyclic heteroaromatic group containing up to 3 heteroatoms selected from N, O and S; R1 represents hydrogen, optionally substituted (C1-4)alkoxy, halo, cyano, optionally substituted (C1-6)alkyl, optionally substituted phenyl, or an optionally substituted 5- or 6-membered heterocyclyl group containing up to 4 heteroatoms selected from N, O and S; when Ar1 is aryl p is not 1, or a pharmaceutical acceptable salt thereof.