Sedative antidepressants are commonly used drugs in the treatment of
insomnia. However, some recommendations claim that only
hypnotics have been proven effective in the treatment of
sleep initiation and maintenance disorders. The aim of this article is to compare the effect of
hypnotics and
trazodone on sleep, and to analyse the evidence for the use of
trazodone in the treatment of
insomnia. Three studies investigated the effects of
trazodone on sleep in
primary insomnia, 5 studies on
insomnia in the course of
affective disorders and 6 studies on
insomnia in other indications (
PTSD,
Alzheimer's disease, alcohol and
opiate dependence,
somatoform disorder, and
insomnia during pregnancy). In the treatment of
insomnia,
trazodone is less effective than
hypnotics in the treatment of sleep onset
insomnia (i.e., disorders of falling asleep). For this indication it needs to be administered earlier than
hypnotics, at least 1 hour before bedtime. It is, however, very effective in the treatment of sleep-maintenance
insomnia, especially in patients with comorbid
mental disorders or patients treated with activating
antidepressants.
Hypnotics and
trazodone have the opposite effect on deep sleep.
Trazodone increases the duration of deep sleep, which is associated with better sleep quality as assessed by patients. In contrast,
hypnotics decrease slow-wave activityin sleep EEG, which is the
biomarker of deep sleep. The main mechanism through which
trazodone promotes sleep is its antagonistic effect on
5-HT2 serotonin receptors, while
hypnotics are agonists of
gamma-aminobutyric acid GABAA receptors, and other
sedative antidepressants block H1
histamine receptors. This is associated with a low risk of
weight gain, which is rare with
trazodone treatment.