1. A method of treating insomnia comprising administering to a mammal in need of such treatment, an effective amount olanzapine or a pharmaceutically acceptable salt thereof. 2. A method of claim 1 wherein olanzapine is Form II olanzapine having a typical x-ray diffraction pattern as follows, wherein d represents the interplanar spacing: d 10.2689 8.577 7.4721 7.125 6.1459 6.071 5.4849 5.2181 5.1251 4.9874 4.7665 4.7158 4.4787 4.3307 4.2294 4.141 3.9873 3.7206 3.5645 3.5366 3.3828 3.2516 3.134 3.0848 3.0638 3.0111 2.8739 2.8102 2.7217 2.6432 2.6007. 3. A method of claim 1 wherein the patient in need of treatment is elderly. 4. A method of claim 1 wherein the patient is suffering from long-term insomnia which has occurred for more than three consecutive weeks. 5. A method of claim 1 wherein the patient has been previously treated with a hypnotic agent. 6. A method of claim 1 wherein the effective amount is from about 1 mg to about 25 mg per day. 7. A method of claim 6 wherein the effective amount is from about 5 mg to about 20 mg per day. 8. A method for treating insomnia wherein such treatment provides no clinically significant alteration of the sleep architecture, comprising administering an effective amount of olanzapine or a pharmaceutically acceptable salt thereof to a patient in need of such treatment. 9. A method of claim 8 wherein the effective amount is from about 5 mg to about 20 mg per day. 10. A method of claim 9 wherein the patient is elderly. 11. A method of claim 6 wherein the olanzapine is Form II olanzapine having a typical x-ray diffraction pattern as follows, wherein d represents the interplanar spacing: d 10.2689 8.577 7.4721 7.125 6.1459 6.071 5.4849 5.2181 5.1251 4.9874 4.7665 4.7158 4.4787 4.3307 4.2294 4.141 3.9873 3.7206 3.5645 3.5366 3.3828 3.2516 3.134 3.0848 3.0638 3.0111 2.8739 2.8102 2.7217 2.6432 2.6007. 12. A use olanzapine or a pharmaceutically acceptable salt thereof in treating insomnia, wherein such treatment provides no clinically significant alteration of the sleep architecture in the mammal in need of such treatment.
METHOD FOR TREATING INSOMNIA