['To investigate whether the outcome of treatment with trazodone CR in primary insomnia differs between patients with and without subthreshold depression.', '14 patients (9 females, mean age 57.3 ± 13.3) with primary insomnia and increased Beck Depression Inventory (BDI) scores (>10) and 15 sex- and age-matched patients with primary insomnia and low BDI scores (≤ 10) were treated with trazodone CR 25-150 mg/d for 3 months and followed for 1 month after discontinuation of the medication. The Athens Insomnia Scale (AIS), Sheehan Disability Scale (SDS), and Clinical Global Impression scale (CGI) were completed at baseline, after each month of treatment and after the first week of run-out phase. Additional assessment tools comprised sleep diaries, the Leeds Sleep Evaluation Questionnaire (LSEQ) and actigraphic recordings.', 'Subjective sleep time increased by 61.5 ± 72.3 min in the group with low BDI and 60.0 ± 59.4 min in the group with increased BDI at the end of the treatment phase. The significant improvements were also observed in the AIS, CGI, LSEQ and SDS. During the run-out phase the improvement was sustained in patients with low BDI, while AIS scores, sleep latency and total sleep time deteriorated in patients with increased BDI.'] Do patients with insomnia and subthreshold depression show marked worsening of insomnia after discontinuation of sleep promoting medication?