Methods for the treatment of sleep disorders

1. A method for the treatment of a sleep disorder selected from dysomnia, insomnia, and circadian rhythmic disorder, in a mammal in need thereof, said method comprising administering an effective amount of a compound of formula (I):

wherein

R is a halogen atom or a C 1-4 alkyl group;

R 1 is hydrogen or a C 1-4 alkyl group;

R 2 is hydrogen, a C 1-4 alkyl, C 2-6 alkenyl or a C 3-7 cycloalkyl group; or R 1 and R 2 together with nitrogen and carbon atom to which they are attached respectively are a 5-6 membered heterocyclic group;

R 3 is a trifluoromethyl, a C 1-4 alkyl, a C 1-4 alkoxy, a trifluoromethoxy, or a halogen group;

R 4 is hydrogen, a (CH 2 ) q R 7 or a (CH 2 ) r CO(CH 2 ) p R 7 group;

R 5 is hydrogen, a C 1-4 alkyl or a COR 6 group;

R 6 is hydrogen, hydroxy, amino, methylamino, dimethylamino, a 5 membered heteroaryl group containing 1 to 3 heteroatoms selected from oxygen, sulphur and nitrogen or a 6 membered heteroaryl group containing 1 to 3 nitrogen atoms;

R 7 is hydrogen, hydroxy or NR 8 R 9 wherein R 8 and R 9 are independently hydrogen or C 1-4 alkyl optionally substituted by hydroxy, or by amino;

R 10 is hydrogen, a C 1-4 alkyl I group or

R 10 together with R 2 is a C 3-7 cycloalkyl group;

m is zero or an integer from 1 to 3; n is zero or an integer from 1 to 3; both p and r are independently zero or an integer from 1 to 4; q is an integer from 1 to 4; provided that, when R 1 and R 2 together with nitrogen and carbon atom to which they are attached respectively are a 5 to 6 membered heterocyclic group, i) m is 1 or 2; ii) when m is 1, R is not fluorine and iii) when m is 2, the two substituents R are not both fluorine,

or a pharmaceutically acceptable salt thereof.

2. The method of claim 1 wherein said mammal is human.

3. A method for the treatment of insomnia in a human in need thereof, said method comprising administering an effective amount of 2-(S)-(4-Fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(R)-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide methanesulphonate.

4. The method according to claim 3 , wherein said method comprises administering orally.

5. A pharmaceutical composition comprising 2-(S)-(4-Fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(R)-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide methanesulphonate and a pharmaceutically acceptable carrier.

6. A method for the treatment of insomnia in a human in need thereof, said method comprising administering an effective amount of 2-(4-fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide or a pharmaceutically acceptable salt thereof.

7. A method for the treatment of insomnia in a human in need thereof, said method comprising administering an effective amount of an enantiomer of 2-(4-fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide or a pharmaceutically acceptable salt thereof.

8. A method for the treatment of insomnia in a human in need thereof, said method comprising administering an effective amount of an 2-(4-fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide.

9. 2-(4-fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide or a pharmaceutically acceptable salt thereof.

10. An enantiomer of 2-(4-fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide or a pharmaceutically acceptable salt thereof.

11. 2-(4-fluoro-2-methyl-phenyl)-piperazine-1-carboxylic acid [1-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methyl-amide.