Lactococcus cremoris YRC3780 improves subjective sleep quality in adults with sleep dissatisfaction: A randomized double-blind placebo-controlled study.

BackgroundLactococcus cremoris YRC3780 (previously Lactococcus lactis subsp. cremoris YRC3780), isolated from kefir, has been suggested to improve sleep quality by acting on intestinal immune cells and promoting cytokine production and has been shown to improve subjective sleep quality in healthy young men without sleep problems.AimWe examined the effects of YRC3780 in subjects dissatisfied with their sleep.MethodsWe investigated the effects of daily YRC3780 intake for 8 weeks on sleep in a randomized, placebo-controlled, double-blind, parallel-group study involving 105 healthy Japanese adults with baseline Athens Insomnia Scale (AIS) scores of ≥6.SummaryAfter 8 weeks, the AIS score and the change from baseline score were significantly better in the YRC3780 group than in the placebo group. The YRC3780 group showed significant improvements compared with the placebo group in the scores for the individual AIS items related to "sleep induction" at 4 weeks and in those for "functioning capacity during the day" at 8 weeks. The percentage changes from baseline at 4 weeks for the Oguri-Shirakawa-Azumi Sleep Inventory Middle-aged and Aged version question "fell asleep quickly" and for the Japanese version of the Epworth Sleepiness Scale question about sleepiness while watching TV were significantly better in the YRC3780 group than in the placebo group. In conclusion, daily YRC3780 intake significantly improved sleep quality and alleviated daytime sleepiness and difficulty falling asleep in healthy Japanese adults with sleep complaints (UMIN-CTR, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno = R000060004, UMIN000052586).