effects of improved sleep quality with administration of melatonin plus gaba on total-body skeletal muscle mass of amateur crossfit athletes

Purpose: sleep and exercise influence each other through complex interactions. sleep disorders incidence in athletes are high among several sports. method: 24 crossfit practitioners, of both genders, between the ages of 25 and 35, presenting difficulty in initiating sleep, with a total sleep time of less than 6 hours per night, were recruited into a double-blind, randomized, placebo-controlled trial that lasted 8 weeks. participants received capsules containing 3 mg of melatonin + 1200 mg of gaba (gamma-aminobutyric acid) or placebo at 10:00 pm daily. sleep quality was assessed using the pittsburgh sleep quality index (psqi), cortisol and testosterone levels were measured and total-body skeletal muscle mass (tbsmm) by lee's equation performed by two different examiners. results: group melatonin + gaba gained an average of 600g of tbsmm while the control group lost 200g (p = 0.295). both groups improve psqi score (p = 0.007). no difference was found in cortisol and testosterone level. conclusions: although there was a difference between groups about tbsmm, it wasn't statistically significant. further studies will be necessary to demonstrate evidence of increased tbsmm from better sleep quality, with a larger number of participants and a longer trial.