Sleep Quality by Sex and Habitual Ergogenic Aid Use in Athletes: A Cross-Sectional Study

This cross-sectional study examined the sex × habitual ergogenic aid use interaction in relation to sleep quality and described athletes’ primary product choices. The final analytical sample comprised 313 athletes (138 female and 175 male), including 112 habitual users (35.8%) and 201 non-users (64.2%). Habitual use was defined as use on at least two days per week for at least one year, and sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). A two-way analysis of variance tested the main effects of sex and habitual use and their interaction. A small interaction was observed, F(1, 309) = 4.01, p = .0461, partial η² = .013. Female habitual users had higher PSQI scores than female non-users (8.00 ± 2.98 vs. 6.55 ± 2.76; d = 0.52, 95% CI [0.05, 0.99]), whereas the male groups were similar (5.75 ± 2.29 vs. 5.80 ± 2.84). Poor sleep (PSQI > 5) was observed in 81.0%, 58.1%, 49.5%, and 51.2% of these groups, respectively. Among habitual users, protein powder (25.3%) and creatine (25.1%) had the largest relative shares of primary product choices. In conclusion, the association between habitual ergogenic aid use and sleep quality may differ by sex, and this pattern should be confirmed in prospective studies that account for product type, dose, and timing of use.