Clinical Summary
Clinical Summary: Efficacy and Tolerability of Ultra–Low-Dose Mirtazapine in Adult Chronic Insomnia
Chronic insomnia remains difficult to treat when cognitive-behavioral therapy for insomnia is contraindicated or when standard sleep medications have not worked. This study addresses a common real-world question in psychiatric practice: whether mirtazapine 3.75 mg offers a tolerable short-term option for treatment-resistant insomnia.
Design
This retrospective chart review
N
N = 53
Population
veterans aged 31–81 years who were prescribed an ultra-low dose of mirtazapine due to the lack of efficacy of traditional sleep aids
Duration
1–3 months after initiating therapy
Key Findings
- Considering all veterans evaluated, 47% showed a clinically significant decrease in ISI score (greater than 7 points).
- Among all patients, 32% achieved recovery, defined as an ISI score of 7 or lower.
- For patients who completed treatment and had a valid ISI score, the mean ISI score was lower at the 1-to 3-month visit than at baseline: 8.9 [6.76] vs. 20.4 [4.58].
- For veterans who completed treatment, the mean change in ISI score 1–3 months after treatment was 11.3 [6.46], and all showed a constant or decreased ISI score.
- Seventeen of the 53 veterans evaluated did not complete treatment.
Clinical Bottom Line
In veterans with chronic insomnia who had not responded to traditional sleep aids, mirtazapine 3.75 mg was associated with substantial short-term improvement in insomnia severity over 1–3 months. The signal is clinically useful for treatment-resistant cases, but the lack of a control group and incomplete follow-up limit conclusions about comparative or long-term benefit.
Practice Implications
- Consider mirtazapine 3.75 mg as a monotherapy option for treatment-resistant insomnia when traditional sleep aids have lacked efficacy.
- Use the Insomnia Severity Index at baseline and again at 1–3 months to track whether patients achieve a clinically significant decrease greater than 7 points or recovery to 7 or lower.
- Set expectations around short-term response: in this cohort, 47% had a clinically significant ISI improvement and 32% reached recovery within 1–3 months.
- Interpret early benefit cautiously in patients who discontinue treatment, because 17 of 53 veterans did not complete treatment and the study does not establish long-term effectiveness.
