SPS-B, a physiological sleep regulator, from the brainstems of sleep-deprived rats, identified as oxidized...

We previously reported regarding the "sleep-promoting substance (SPS)," which was isolated from the brainstem extract of sleep-deprived rats, the existence of multiple active components including uridine and SPS-B. Intracerebroventricular infusion of crude SPS-B exhibited significant enhancing effects on both slow wave sleep and paradoxical sleep in unrestrained rats. Further investigation of SPS-B has resulted in its final identification as oxidized glutathione (GSSG, gamma-glutamylcysteinylglycine disulfide). Authentic GSSG similarly administered in rats also significantly enhanced sleep which was indistinguishable from normal physiological sleep. We propose GSSG as a candidate endogenous sleep substance.