Hello, Based on your description of complaints, your mother does have insomnia, which is secondary to the Schizophrenia that she is diagnosed with. Seroquel (Quetiapine) is known to have sleepiness as a side-effect, which is of advantage in schizophrenic patients suffering from sleepless nights. If the dose of 600 mg is not working, it is unlikely to work at higher doses for the specific complaint of sleep. There appears to be an obvious need for ensuring lifestyle modification to check day-time sleep and of revising the on-going treatment regimen. The choice of the appropriate medication should rest in the hands of a Psychiatrist who has seen your mother regularly and whom you can take regular follow-up sessions with. If I was in that place, I would ensure that the current medicine has successfully controlled her disease (psychosis and anxiety) symptoms. There needs to be a possibility of another co-morbid diagnosis to be ruled out along with the underlying schizophrenia. Thereafter, the appropriate change in medicine dose or regime should be done. Usually other anti-psychotic drug molecules with sedative side-effects are used in small doses to supplement an on-going treatment. The use of benzodiazepines (sleeping pills) is not recommended for a long term solution. I would advise you to run a detailed consultation with work-up of current symptoms, in order to efficiently manage her sleep and its possible underlying factors. Hope this addresses your concern. Feel free to ask any more questions.