A phase I study evaluated doses up to 80 mg, resulting in significant improvement in sleep latency without adverse effects.
In randomized, double-blind, placebo-controlled crossover trials, the 10 and 30 mg doses increased sleep time and reduced sleep latency. The subsequent study added a 60 mg dose and observed dose-dependent sleep promotion.
^Bettica, P; Nucci, G; Pyke, C; et al. (Aug 2012). "Phase I studies on the safety, tolerability, pharmacokinetics and pharmacodynamics of SB-649868, a novel dual orexin receptor antagonist". Journal of Psychopharmacology. 26: 1058–1070. doi:10.1177/0269881111408954. PMID21730017.CS1 maint: Explicit use of et al. (link)