Sedating Antidepressant Improves Driving Safety in Patients With Major Depressive Disorder

In the treatment of depression, the role of sleep is important as there are mutual relationships between mood disorder and sleep disorders. Over 80% of major depressive disorder (MDD) patients report sleeping problems. Depression can strongly impair cognitive functioning and daytime alertness. (Mirtazapine (Remeron) is an antidepressant and sleep-promoting agent that has been available in Canada for a few years. However, research investigating the effects of mirtazapine on sleep is limited and it is not known what are the short- and long-term changes in sleep architecture associated with this drug and if daytime performance is affected. Rationale: The co-existence of depression and sleep difficulties are very common. Mirtazapine is marketed as a single modality of treatment for both depression and impaired sleep. As a sleep clinic in a psychiatry department, a single modality of treatment for depressive and sleep disorders is preferred by patients and can help improve compliance to treatment. However, there are only 7 published studies investigating the effects of mirtazapine and sleep and these have significant limitations. None of these studies have objectively examined mirtazapine's short- and long-term on sleep architecture and daytime function (daytime sleepiness, alertness, driving performance) in depressed patients. This study will address these issues. Hypothesis: I) Mirtazapine will produce both immediate and long- improvement effects on sleep in patients with major depressive disorders. There may be impairments in alertness for the first two days after starting treatment but daytime alertness will recover after one week. II) Patients treated with mitrazapine will show a rapid, initial improvement in driving performance with recovery of sleep and slower, further improvement as treatment of their depression translates into better sleep quality as well as improvements in attention, alertness and concentration. Study Design: This pilot proposal is a two-part longitudinal, open-label clinical study with consecutive enrollment of subjects. This research study will take place in conjunction with normal clinical practice. Patients with depression and sleep disorders are commonly seen in our sleep clinic and mirtazapine is one of several antidepressants that is prescribed by our clinicians. In this study, we will follow a group of patients who have been prescribed mirtazapine by one of our clinic physicians and who meet the inclusion and exclusion listed below. There will be an additional number of sleep studies (10 total versus the usual 2 or 3) performed; the usual daytime testing will be conducted as part of the standard of care (Multiple Sleep Latency Test (MSLT) and Maintenance of Wakefulness Test (MWT)); we will administer additional questionnaires to assess subjective sleepiness, alertness and fatigue; and, driving simulator testing will be conducted in accordance with our normal standard of care.