Key Takeaways
Extended Takeaways
- This cohort reflects a highly treatment-resistant population: all 151 patients had failed 4 or more antidepressant medications from at least 2 classes and unsuccessful psychotherapy, so the null daylight finding was observed in a clinically difficult-to-treat sample.
- The rTMS course was standardized to an FDA-approved Deep TMS H1-coil protocol targeting the left dorsolateral prefrontal cortex with 18-Hz stimulation, 2-second trains, 20 seconds between trains, 55 trains, 1,980 pulses over 20 minutes, at 120% of the motor threshold.
- Outcome definitions were clinically stringent, with response requiring a 50% or greater decrease on PHQ-9 or HDRS and remission requiring PHQ-9 <5 or HDRS <7; clinicians should interpret the negative seasonal signal in the context of these standard endpoints.
- Median average daylight exposure during treatment varied little across groups—704 minutes in responders, 701 minutes in remitters, and 718 minutes in nonresponders—supporting that any effect of ambient daylight, if present, is likely small relative to other determinants of rTMS outcome.
- Because the data were non-Gaussian by Shapiro-Wilk testing and compared with the Mann-Whitney U test, the analysis was based on distribution-appropriate nonparametric methods rather than assumptions of normality.
- The study design included only patients who completed the full 9-week course, with daily treatment for 6 weeks followed by a taper of 3 sessions at week 7, 2 sessions at week 8, and 1 session at week 9; these results should therefore be applied most directly to completers rather than early discontinuers.
