Abstract
This study investigated the effect of the intake of high (HGI) or low glycemic index (LGI) high-carbohydrate meals on athletes' sleep. Nine basketball adult male athletes were assessed during a championship and received high-carbohydrate meals (dinner and evening snack) with HGI or LGI. Quantitative and qualitative sleep variables were assessed: sleep latency (LAT), sleep efficiency (EFIC), Wake After Sleep Onset (WASO), sleep time through actigraphy and sleep diary. Dietary intake, satiety, sleepiness, glycemic response, salivary cortisol and melatonin were also assessed. On both days most athletes had LAT and WASO higher than recommendation, and nocturnal sleep time below the recommendations. There was no difference between sleep and hormonal parameters according to GI dietary manipulations; however, correlations were observed between sleep and diet. Daily energy intake had negative correlation with efficiency and nocturnal total sleep time, and a positive correlation with WASO, regardless of the GI nocturnal meals. No differences were observed in salivary cortisol and melatonin according to GI. The results suggest that food intake throughout the day seems to exert more influence on sleep parameters of basketball players than GI manipulation of evening meals on the pre-night game, but further studies are necessary to better understand this complex relationship.
Highlights
Diet plays an important role in athletes’performance (ACSM 2016)
Considering the lack of studies which investigate the variables related to sleep quality in athletes, we aimed to examine the effect of high (HGI) or low (LGI) glycemic index (GI) carbohydrate-rich meals on sleep parameters during a competition
The results indicate that the majority of athletes presented poor sleep quality both usually (PSQI assessment) and during competition; the GI manipulation did not cause significant differences in sleep parameters; energy and nutrient intake e20180107 7 | 14
Summary
Among several dietary strategies used to optimize athletic performance, there is a consensus about the importance of carbohydrate intake before competitions (Burke et al 2011, ACSM 2016). Studies show that diet can affect sleep (Afaghi et al 2007, Lindseth et al 2013, Nehme et al 2014, Peuhkuri et al 2012), and sleep can impact on athletic performance (Jullif et al 2015). Studies conducted with non-athletes suggest that glycemic index (GI) manipulation can affect sleep, since high GI food intake reduced sleep onset latency (Afaghi et al 2007). The ingestion of carbohydrate-rich drinks before, during and after a cycling training [totalizing 9.9(1.5) g/ kg/day] was associated with lower sleep time than in control group (without carbohydrate increase) [7.4(1.6) g/kg/day], and the authors suggested that control group would need more sleep time to exercise recover (Killer et al 2015)
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