Sertraline and periodic limb movements during sleep: an 8-week open-label study in depressed patients with insomnia

Previous studies have reported that selective serotonin reuptake inhibitors (SSRIs) might induce or exacerbate periodic limb movements during sleep (PLMS). However, most of these studies were retrospective and cross-sectional studies with small sample sizes on a selective SSRI, fluoxetine. Because different SSRIs have different pharmacologic profiles, it was not certain if other SSRIs also might lead to PLMS.

Data were taken from an open-label 8-week trial of sertraline in depressive patients with insomnia (n=31). Depressed patients were administered sertraline 50mg at 8:00am on the first day, and the dosage was subsequently titrated up to a maximum of 200mg daily during the 8-week trial. All participants were tested by repeated polysomnography (PSG) (baseline, first day, 14th day, 28th day, and 56th day). Periodic leg movements (PLM) were visually counted and the PLM index (PLMI) was calculated. PLMS was defined as PLMI ⩾5, and significant PLMS was defined as PLMI ⩾15.

Compared with baseline (PLMI, 3.6±1.5), all PLMI indices increased on the immediate administration of sertraline on the first day (PLMI, 5.1±3.9). From the 14th day onward, PLMI became stable and significantly higher than baseline and the first day (8.7±3.1 on the 14th day, 8.3±3.7 on the 28th day, and 8.5±3.6 on the 56th day; F[11.81]; P=.003). The clinical responses and PSG characteristics continuously improved during the 8-week trial. The PLMS group (PLMI ⩾5) had a higher arousal index (AI) than the non-PLMS group on the 14th day (9.4±5.5 vs 5.2±3.7; t test, 4.22; P=.03) and the 56th day (8.1±5.5 vs 4.3±3.7; z score, 3.11; P=.04); albeit, there was no significant clinical disturbances in the PLMS group.

PLMS were increased during sertraline treatment, but only a few of the PLMS reached the significant level. This effect of sertraline on PLMS might be dosage dependent. Although the sertraline-induced PLMS did not seem to cause significant clinical disturbance, the PLMS group (PLMI ⩾5) had a higher AI than the non-PLMS group. Thus clinicians should pay more attention to PLMS during SSRI antidepressant treatment.