Over the last two decades, doctors treating sleep disorders have prescribed more antidepressants for sleep than insomnia drugs, according to several published analyses. A sample of 3,400 physicians’ prescription practices published in the journal Sleep in 2004 showed that antidepressants were approximately 1.53 times more likely to be prescribed by American doctors than insomnia drugs. There is similar tendency in Scandinavia and other European countries as well. However, there is insufficient evidence that most antidepressants are effective in treating insomnia, concluded a National Institutes of Health panel that convened on the topic in 2005.
Some of the older antidepressants like amitriptyline and dosulepin are themselves a sedative. As a result, they have been used a great deal to help depressed patients with sleep problems. However, they don’t promote ‘normal’ sleep. According to experts antidepressants do not increase the amount of deep sleep. Even though they can help getting off to sleep, they tend not to prevent people still waking in the morning feeling exhausted.
Given the strong bi-directional relationship between depression and insomnia, several studies have assessed the effects of antidepressants on sleep continuity and sleep architecture. In general, antidepressants tend to suppress REM sleep and increase the time taken to enter REM sleep. Both increased REM sleep density and reduced latency to REM sleep are characteristic of patients with depression and thus antidepressants appear to normalise these parameters. Indeed, many clinicians will often give out off-label prescriptions of antidepressants for poor sleep, rather than sleeping pills, due to the perception that they are less habit-forming – and so can be taken for longer – and that they have less potential for side-effects.
A few of the newer antidepressants are sedative. These include mirtazapine and trazodone. Mirtazepine is an effective antidepressant and the sleep it promotes is more normal than with drugs like amitriptyline. Trazodone is an antidepressant, but many doctors feel that it is not as effective as other antidepressants. However, it has relatively few side effects and promotes a good quality sleep. Because, like all antidepressants, it does not cause people to become dependent on it, trazodone is sometimes used in low doses instead of a benzodiazepine to help sleep problems, in addition to an different non-sedative antidepressant.
Antidepressants (such as doxepin, trimipramine, mirtazapine and trazodone) have been successful in treating poor sleep in the (very) short term. However, the impact often lasts only one week. These drugs don’t generally suit long term use. Also, they may cause severe ‘hangover’ effects and heavy drowsiness the next morning that can last till noon or even longer. Other side effects can include headache, night sweats, nausea, agitation, sexual problems and dry mouth.
It is important to note that studies and trials of antidepressants effect on sleep are lacking and current guidelines do not recommend wide use.