Can controlled motivation contribute to desired educational outcomes such as academic achievement over and above autonomous motivation? No, According to Self-Determination Theory. Yet, some recent findings have shown that controlled motivation may not fully undermine motivated behavior when autonomous motivation remains high. In this study, we tested this possibility through two different samples of more than 3000 Turkish adolescent students. Through polynomial regression and response surface analyses we found only slim evidence that high controlled motivation can predict higher grades. Instead, a consistent finding that emerged was that higher grades were expected when high levels of autonomous motivation coincided with low levels of controlled motivation rather than high levels of controlled motivation. These findings highlight the usefulness of polynomial regressions and response surface analyses to examine pertinent questions which challenge the view that controlled motivation may not be as much detrimental as self-determination theory claims to be.

In two diary studies, we examined the reciprocal daily association between the satisfaction and frustration of adolescents’ basic psychological needs and sleep, and the role of stress and fatigue in these associations. In Study 1 (N = 211; 52% female; Mage = 15.86 years, SD = 1.18 years), daily need experiences were unrelated to daily fluctuations in subjective sleep outcomes. However, shorter daily sleep quantity was related to higher daily fatigue, which in turn related to more daily need frustration and less need satisfaction. Study 2 (N = 51; 49% female; Mage = 15.88 years, SD = 2.88 years) extended these findings by demonstrating that daily need frustration related to shorter objective sleep quantity and longer wake after sleep onset, indirectly through higher symptoms of stress. Poor sleep quality also related to worse need experiences via higher daily fatigue. These findings underscore the dynamic interplay between daily need experiences and adolescent sleep.