Trimipramine doesnt. It „brightens“ REM, whereas many other antidepressants shorten it. According to studies(copied from wiki): „Trimipramine is unique in that it is an exception and produces antidepressant effects without compromising or otherwise affecting REM sleep. Even long-term treatment with trimipramine for up to 2 years has not been found to suppress REM sleep.“.Yes. Almost all sedatives mess up your REM cycle. Sure, you fall asleep more easily, but the quality of sleep is worse.
