Life Satisfaction and Academic Achievement among Tanzanian College Students: Mediated by Sleep Quality and Moderated by Smartphone Addiction

Academic achievement is vital for socioeconomic advancement, particularly in developing countries like Tanzania. While cognitive factors of academic achievement have been widely studied, psychosocial and behavioral influences such as life satisfaction, sleep quality, and smartphone addiction remain underexplored. To address this research gap, this study examines how life satisfaction affects academic achievement through sleep quality, with smartphone addiction as a moderator. Data were collected from 513 Tanzanian college students and analyzed using SPSS 27 and PROCESS Macro Models 4 and 59, controlling for age, sponsorship, and occupation. Research results showed that life satisfaction was positively correlated with academic achievement ( r  = 0.578) and sleep quality ( r  = 0.638), while smartphone addiction showed negative correlations with these three variables. Sleep quality partially mediated the link between life satisfaction and academic achievement, accounting for 30.77% of the total effect. Moderated mediation analysis revealed that smartphone addiction strengthened the positive relationship between life satisfaction and sleep quality (effect sizes: 0.437 to 0.642, all p  < 0.001), but weakened the link between sleep quality and academic achievement (effect sizes: 0.339 to 0.108, all p  < 0.001). These findings highlight the dual moderating role of smartphone addiction and underscore the importance of promoting psychological well-being and responsible technology use in academic contexts.