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Abstract

We analyzed the effects of wearing blue lenses on melatonin level, physical and cognitive performance. Fifteen youth volleyball players (15.0 ± 1.5 yrs) attended the laboratory on 3 occasions (48-h interval): on the 1 st visit they were familiarized with the procedures of the study, and on 2 nd and 3 rd visits they were submitted to the testing protocol wearing transparent (control) or blue lens glasses in a counterbalanced crossover design. The protocol consisted of 10 min in "total darkness," 30 min of light stimulation (wearing blue or transparent lenses), followed by an attentional test, and an agility T-test (without wearing the glasses). Samples of saliva (to determine melatonin concentration) were obtained pre-and post-exposure (30 min) to artificial light, wearing the lenses. Sleepiness, alertness, attention, mood, and perceived recovery status and performance variables (reaction time and T-test) were assessed after lens exposure. Melatonin levels did not differ within and between groups (blue lenses, pre: 0.79 ± 0.73 and post: 1.19 ± 1.374 pg/ dl, p = 0.252, effect size (ES) = 0.38; control, pre: 0.97 ± 1.00 and post: 0.67 ± 0.71 pg/dl, p = 0.305, ES = -0.35). Nonetheless, melatonin differences were significantly correlated with physical sedation for glasses with blue lenses (r = −0.526; p = 0.04). No other variables differed (p > 0.05) between protocols, including T-test performance (p = 0.07; ES = 0.41). Blue lenses do not influence melatonin levels, cognitive/physical performance, and mood status in amateur youth volleyball players.