Effect of low-frequency repetitive transcranial magnetic stimulation as adjunctive treatment for insomnia patients under hypnotics: A randomized, double-blind, sham-controlled study

Abstract

Background: Pharmacotherapy of insomnia is prescribed often but may be complicated by drug dependence. Cognitive-behavioral therapy for insomnia is effective, but requires time to take effect. Repetitive transcranial magnetic stimulation (rTMS) is effective for depression but of uncertain benefit for insomnia. We studied low-frequency rTMS of the left dorsal medial prefrontal cortex (DMPFC) as an adjunctive therapy of insomnia. Methods: We recruited 60 patients with insomnia, of whom 49 completed the study. We applied 1 Hz rTMS to the DMPFC in the experimental group (n = 36) and sham coil for the placebo group (n = 13). Outcome measures included objective polysomnography (PSG) and subjective Pittsburgh Sleep Quality Index (PSQI). All participants were requested to continue prescribed pharmacotherapy. Results: After 10 sessions of low-frequency DMPFC-rTMS, the experimental group demonstrated a reduction of duration of wake after sleep onset (WASO) from 75.4 (±53.3) to 51.2 (±75.1) min (p = 0.011). Sleep efficiency (SE) increased from 74.6% (±15.6) to 80.8% (±13.8) (p = 0.004). The sham group experienced improved SE from 79.4% (±30.7) to 88.9% (±5.6) (p = 0.039). After controlling for baseline PSG parameters and hypnotic dosage, the sham group exhibited better effects of sleep onset latency and SE than the rTMS group but no difference on PSQI. Conclusion: Although the effects of rTMS and sham coil on insomnia were similar (which implied significant placebo effect), low-frequency DMPFC-rTMS might offer a safe, non-invasive, and useful adjunctive therapy of insomnia by reducing WASO. The DMPFC may represent a new target for future rTMS insomnia studies.