Possible treatment of circadian sleep disorders using daily ketotifen administration

Classic H1 histamine receptor (H1R) antagonists are currently used as over-the-counter sleep aids. However, their overdose administrations rather produce wakefulness. Our previous rat model studies suggest that ketotifen, an early-phase, second-generation H1R antagonist may be a more desirable sleep aid. Here, we further examined daily injections of ketotifen (3 mg/kg, intraperitoneally, for 5 days) 3 h before light onset time in rats and analyzed the effect of ketotifen on the successive free-running locomotor activity rhythms under constant dim red light. We found significant phase-advancement by the daily ketotifen injections, suggesting possible treatment of circadian sleep disorders using daily ketotifen administration.