Acute and sub-chronic administration of olanzapine has shown a favourable effect on the sleep disturbances in previously medicated schizophrenia patients with predominantly negative symptoms. The present study will be carried out to clarify the effect of olanzapine on polysomnographic profiles of schizophrenia patients in an acute phase of illness after controlling for the drug effects.

Twenty schizophrenia patients (11 drug naïve and 9 drug free) will be studied over a period of six weeks of olanzapine treatment. Patients will be assessed at the baseline on BPRS, PANSS, CDSS and UKU side effect rating scales and a baseline 40 channels polysomnography will be done. After the initial assessment, patients will put on olanzapine treatment, in flexible dosages based on clinical response, for a period of six weeks when a final assessment on clinical rating scales and polysomnography will be done. The sleep data will be scored manually for staging based on Rechtschaffen and Kales criteria.

Inclusion Criteria:

1. Male patients fulfilling International Classification of Diseases-10 Diagnostic Criteria for Research for schizophrenia
2. Aged 18-50 Yrs
3. Drug naïve or drug free (not receiving any psychotropic medication for the past 4 months)
4. Consenting

Exclusion Criteria:

1. Any comorbid psychiatric illness
2. Significant medical or neurological illness
3. History of significant head injury, epilepsy
4. Substance use in the past 4 months excluding nicotine and caffeine
5. Presence of a primary sleep disorder