Correlation between sleep and psychological mood states in female wheelchair basketball players on a Japanese national team.

With only 17 players, the correlations may not apply to other wheelchair athletes. Sleep and mood were measured by self-report questionnaires, so recall or reporting bias could affect the results. The design was cross-sectional, so it cannot show that better sleep causes higher vigor or lower tension. Players were tested on the first day of a training camp after main competition had finished, and timing in the season may have affected mood. The PSQI was asked about the past week rather than the usual past month, so the sleep findings may not match standard PSQI interpretations. Users of sleep medication were excluded, and the number excluded was not disclosed, so the sample may not represent players who use such medication. The general population comparison used external published data from Japanese women aged 30 to 39 years, not a matched control group from the same setting.

Do not conclude that improving sleep will raise vigor or athletic performance. The study was cross-sectional and included 17 players, so it shows association, not cause. It also did not find a significant correlation between sleep duration and mood states.