Suvorexant (Belsomra) for the Treatment of Bipolar Depression With Insomnia

The investigators are doing this research study to find out if suvorexant (Belsomra) can help people with bipolar depression when added to their usual treatment. The investigators also want to find out if suvorexant (Belsomra) is safe to take without causing too many side effects in people with bipolar disorder. Suvorexant (Belsomra) is approved by the U.S. Food and Drug Administration (FDA) to treat insomnia. It has not yet been studied in people with bipolar disorder who have problems sleeping. This research study will compare suvorexant (Belsomra) to placebo. The placebo looks exactly like suvorexant (Belsomra), but contains no suvorexant (Belsomra). During this study participants may get a placebo instead of suvorexant (Belsomra). Placebos are used in research studies to see if the results are due to the study drug or due to other reasons. This study has two parts, each lasting 6 weeks. During each part, participants may receive either Belsomra or placebo. Some participants will receive suvorexant for both parts, some will receive placebo for both parts, and others will receive suvorexant during one part and placebo during the other part. Placebos are used in research studies to see if the results are due to the study drug or due to other reasons. This study is open to people with bipolar disorder who have trouble sleeping. Bipolar disorder is a brain disorder associated with episodes of mood swings ranging from depressive lows to manic highs. About 80 subjects will take part in this research study. All subjects will be enrolled at Massachusetts General Hospital (MGH).