Creatine Improves Total Sleep Duration Following Resistance Training Days versus Non-Resistance Training Days among Naturally Menstruating Females.

Females historically experience sleep disturbances and overall poor sleep compared to males. Creatine has been proposed to impact sleep; however, the effects are not well known. The purpose of this study was to examine the effects of creatine supplementation on sleep among naturally menstruating females. Twenty-one participants completed a double-blind, randomized controlled trial in which they consumed 5 g creatine + 5 g maltodextrin or placebo, 10 g maltodextrin, daily for 6 weeks. Participants completed resistance training 2x/week using the TONAL (Tonal Systems Inc., San Francisco, CA, USA) at-home gym. Pre- and post-testing assessed body composition, Pittsburgh Sleep Quality Index (PSQI), dietary intake, and muscular strength. Sleep was assessed nightly using an ŌURA (Oulu, Finland) ring. Compared to the placebo group, those consuming creatine experienced significant increases in total sleep on training days ( = 0.013). No significant changes in chronic sleep and PSQI (pre-post) were observed. There was a significant increase in TONAL strength score over time ( < 0.001), with no between-group differences. Participants reduced their total calorie (kcal) ( = 0.039), protein (g/kg) ( = 0.009), carbohydrate (g/kg) ( = 0.023), and fat (g) ( = 0.036) intake over time. Creatine supplementation increases sleep duration on resistance training days in naturally menstruating females.