Antidepressants and sleep: a qualitative review of the literature

Abstract

Most antidepressants change sleep; in particular, they alter the physiological patterns of sleep stages recorded overnight with EEG and other physiological measures. These effects are greatest and most consistent on rapid eye movement (REM) sleep, and tend to be in the opposite direction to the sleep abnormalities found in major depression, but are usually of greater degree. Reductions in the amount of REM sleep and increases in REM sleep onset latency are seen after taking antidepressants, both in healthy volunteers and in depressed patients. Antidepressants that increase serotonin function by blocking reuptake or by inhibiting metabolism have the greatest effect on REM sleep. The decrease in amount of REM sleep appears to be greatest early in treatment, and gradually diminishes during long-term treatment, except after monoamine oxidase inhibitors when REM sleep is often absent for many months. Sleep initiation and maintenance are also affected by antidepressants, but the effects are much less consistent between drugs. Some antidepressants such as clomipramine and the selective serotonin receptor inhibitors (SSRIs), particularly fluoxetine, are sleep-disturbing early in treatment and some others such as amitriptyline and the newer serotonin 5-HT2-receptor antagonists are sleep promoting. However, these effects are fairly short-lived and there are very few significant differences between drugs after a few weeks of treatment. In general, the objectively measured sleep of depressed patients improves during 3-4 weeks of effective antidepressant treatment with most agents, as does their subjective impression of their sleep. Sleep improvement earlier in treatment may be an important clinical goal in some patients, perhaps when insomnia is particularly distressing, or to ensure compliance. In these patients, the choice of a safely used and effective antidepressant which improves sleep in short term is indicated. Patients with other sleep disorders such as restless legs syndrome and REM sleep behaviour disorder should be identified before choosing a treatment, as some antidepressants worsen these conditions. Conversely, there is evidence that some antidepressants may be useful in the treatment of sleep disorders such as night terrors.