Document Type : Research Paper


1 Irmandade da Santa Casa de Sao Paulo

2 Irmandade da Santa Casa de São Paulo

3 Department of Neurology and Sleep Medicine Sao Leopoldo Mandic Medical College, Campinas

4 Cilla nutrition center

5 Santa Marcelina Medical College

6 Hospital Israelita Albert Einstein


Introduction: Sleep and exercise influence each other through complex interactions. Sleep disorders incidence in athletes are high among several sports. People who suffer from sleep disorders have impaired sports performance and difficulty gaining muscle mass. Hormone levels such as testosterone and cortisol may be altered as a cause or consequence. So, improving sleep quality and a careful assessment of other tests are key to improving performance in sport.
Material and Methods: 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.
Conclusion: 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.