Similarly, positive relation between achievement motivation
and school performance was found by Meijer and Wittenboer
[6]. The authors analyzed the joint influence of sleeping time,
intelligence, eagerness and achievement motivation on school
performance in the last two grades of elementary school (age
M=11,7). Results of the study showed that less chronic sleep
reduction, greater eagerness, higher achievement motivation
and intelligence rise a better school performance [6]. According
to the authors, those variables explain together 43% of the
variance in school performance.