While trazodone is rarely used to treat depression alone any more, it's widely prescribed, off-label, at lower doses for treating insomnia, for several likely reasons.
First, trazodone has one distinct advantage—and possibly a few others. It's generic, so it's considerably cheaper than many of the other widely prescribed sleep medications-about $3 for a week's supply, vs. $45 and $34 for eszopiclone (Lunesta), and ramelteon (Rozerem) for a week's supply. (The other frequently used drug, zolpidem, or Ambien, is available as a generic, at $15 for a week's worth.) And while some of the insomnia drugs like Sonata,Ambien and Lunesta are classified by the FDA as controlled substances and require doctors and pharmacists to take additional steps before they're prescribed or dispensed; trazodone is not a controlled substance, so doctors can prescribe it without constraints.
In addition, many physicians apparently think that trazodone is safer than other frequently prescribed sleep medications. But whether that's correct is not clear.
It's true that the other drugs can impair your ability to recall new experiences, and may even—although rarely—cause you to walk, eat, have sex, or drive a car while still essentially unconscious. We could find no evidence to date of those problems having been reported with trazodone. Moreover, many doctors seem to believe that trazodone is less likely than even the newer sleep drugs to cause dependency and, when discontinued, renewed insomnia. Yet there's little evidence to prove or disprove those ideas.
And, trazodone has certain risks of its own. In particular, it's more likely than the newer sleep drugs, particularly the short-acting ones, to leave you feeling drowsy the next day, which increases the chance of accidents. It can also cause abnormally low blood pressure and, in turn, dizziness or even fainting, particularly in seniors.
Trazodone can also cause heart-rhythm disorders. It might possibly weaken the immune system. And some evidence suggests it can cause priapism, or persistent erection, a medical emergency that may require surgery and can lead to impotence if not treated promptly. Moreover, a black-box warning in the package insert notes that trazodone, like other antidepressants, can increase the risk of suicidal thoughts and behavior in children and adolescents.