Document Type : Original Article
Authors
1
PhD in Exercise Physiology, Salami Azad University, Central Tehran Branch, Lecturer, Shahid Sattari Air Force University, Tehran, Iran.
2
PhD in Exercise Physiology, Faculty of Psychology and Educational Sciences, Mohaghegh Ardabili University, Ardabil, Iran.
3
PhD in Exercise Physiology, Baqiyatallah University, Lecturer, Imam Ali Military University , Tehran, Iran
10.22038/jpsr.2025.86479.2688
Abstract
Purpose:
Sleep deprivation can negatively impact cognitive function and working memory. This study investigates the effects of caffeine and melatonin supplementation on these indices in soldiers.
Method:
The present study was semi-experimental and applied with a pre-test and post-test design. The statistical sample comprised 55 soldiers divided into 5 groups: sleep deprivation-caffeine (10 subjects), sleep deprivation-melatonin (10 subjects), sleep deprivation-placebo (10 subjects), melatonin-sleep (10 subjects), and full sleep (10 subjects). The Functional Movement Screening (FMS) were used to measure functional performance and working memory (N-BACK) variables, respectively. Cognitive and functional indices were measured for all subjects after a normal night’s sleep. Subjects in all groups consumed 400 mg of caffeine, melatonin, or a placebo after 28 hours of sleep deprivation, and then all pre-test procedures were repeated after 30 hours. Statistical analysis was performed using SPSS version 28 and a one-way analysis of variance with repeated measures. The Bonferroni post-hoc test was used to compare within-group differences in results.
Result:
The effect of the group factor on performance index (p<0.001) (η2=0.402), accuracy (1-back) (p<0.001) (η2=0.504), reaction time (1-back) (p<0.001) (η2=0.449), accuracy (2-back) (p<0.001) (η2=0.469), and reaction time (2-back) (p<0.001) (η2=0.510) were significantly different between groups (Table 2). In addition, the interaction effect of time*group on the performance index (p<0.001) (η2=0.836), accuracy (1-back) (p<0.001) (η2=0.656), reaction time (1-back) (p<0.001) (η2=0.740), accuracy (2-back) (p<0.001) (η2=0.476), and reaction time (2-back) (p<0.001) (η2=0.797) had significant differences betweengroups.
Conclusion:
Caffeine and melatonin supplements can significantly improve working memory and performance in sleep-deprived soldiers. However, more research is needed to determine optimal dosage and timing, as well as to investigate long-term side effects. Application of these supplements should be limited to specific conditions and under medical supervision to achieve the best results and avoid potential risks.
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