Procedures
PD, abnormal behaviors
After baseline sleep, neurological and psychological assessments, participants entered a 4-week baseline observation period. No change in melatonin or antidepressant treatment was allowed during the study. Participants on clonazepam tapered off this medication during the baseline period to avoid interactions with the study drug. Patients followed a titration schedule of 50% dose reduction weekly until reaching 0.25 mg dose at which point they discontinued the drug. Patients completed an RBD diary daily, after consultation with their bedpartner and/or after review of their home video monitor footages, reporting number, and description of abnormal behaviors. Entry PSG occurred on the last night of the baseline period. Participants using positive airway pressure therapy at home received treatment during PSG. Patients were randomized to SXB or placebo in a 1:1 ratio, using permuted blocks of six, stratified by PD status. Study drug and placebo containers were each labeled with a code assigned by a random number generator. One investigator (CK) was responsible for the random allocation sequence and intervention assignment; all other research personnel and participants were blinded. Starting dose was 4.5 g nightly divided into two doses taken 2.5–4 hours apart, following a prior PD protocol [