Of the 29 research studies, the majority (n=23) provided evidence for a significant seasonal pattern for mania, while the other 6 studies did not. Most of the studies reported that mania occurred more often during spring and summer and that depression occurred more often during fall and winter. The authors of the studies estimated a prevalence of seasonal mania of 15% among patients with bipolar disorder. It is hypothesized that the underlying mechanism for seasonal mania may be hypersensitivity to bright light that suppresses melatonin production. Both lithium and valproate can counteract the action of bright light in suppressing melatonin and prolong sleep-wake cycles in the circadian rhythms of patients with bipolar disorder. These effects may at least partially explain their efficacy as mood stabilizing agents. No research studies were located that provided information on managing the medication regimen, especially of mood stabilizing medications, based on the seasonal patterns seen in some patients with bipolar disorder in order to reduce the risk of relapse associated with seasonal mania. Positive findings in this area might lead to a new paradigm for the management of patients with bipolar disorder who have seasonal mania.

No abstract