The sleep experiment used matching when allocating CBD-first and placebo-first sequences. Matching supported baseline comparability but did not make the two sessions interchangeable or prove that all order effects were absent.
How sequence allocation worked
Eligible volunteers were matched on sex, age and education. The treatment sequence for one member of a pair was chosen blindly, and the matched participant received the remaining sequence. One volunteer withdrew, leaving twenty-six participants assessed on two occasions separated by two weeks.
Each participant received a single 300 mg CBD dose on one occasion and placebo on the other, under otherwise similar overnight procedures.
Matching and crossover serve different roles
Matching concerns allocation across participants. Crossover allows comparison of conditions within a participant. Neither substitutes for examining sequence, timing and possible differences between visits. The statistical analysis included drug-administration order rather than assuming it was irrelevant.
Retain the measured conclusion
Conventional polysomnographic, cognitive and subjective comparisons did not show significant CBD-placebo differences. The allocation detail strengthens understanding of the comparison, but it does not convert nonsignificance into formal equivalence or establish effectiveness for insomnia. This was an acute experiment in selected healthy volunteers, with a specific formulation and dose.
Related reading: limits on proposed CBD mechanisms.
Research cited
Linares and colleagues (2018). No Acute Effects of Cannabidiol on the Sleep-Wake Cycle of Healthy Subjects: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study. DOI: 10.3389/fphar.2018.00315.
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