Poor sleep quality can cause various health problems. Despite this evidence, much research demonstrates significant heterogeneity in the amounts that people sleep across cultures. This suggests that despite serving fundamental biological functions, sleep is also subject to cultural influence. Variations in chronotype and problematic smartphone use influence sleep quality, and both poor sleep and smartphone addiction can result in poor health and academic performance. This study aimed to measure the associations between chronotype, sleep quality, and smartphone addiction in a population of 1210 health sciences university students in Morocco and Spain. The Horne and Ostberg Morningness-Eveningness Questionnaire, Pittsburgh Sleep Quality Index, and Smartphone Addiction Scale were used to assess the study variables. The study found that the majority of students belonged to the "Neutral" chronotype (73.9%), that the prevalence of smartphone addiction was fairly high (46.3%), and that the prevalence of poor sleep quality was high (74.0%). Associations were found between chronotype and smartphone addiction ( < 0.001), subjective sleep quality ( = 0.006), sleep duration ( = 0.005), sleep disturbances ( = 0.013), and use of sleep medications ( = 0.003). Chronotype was also associated with gender ( = 0.009), country of study ( < 0.001), field of study ( < 0.001), and chronic health problems ( = 0.001). Associations between chronotype and field of study ( < 0.001 for the evening chronotype), sleep disturbance ( < 0.001 and = 0.026 for both the evening and morning chronotypes), and smartphone addiction ( < 0.001 for the morning chronotype) were confirmed in the multivariate analysis. Our study highlights associations with chronotype that affect sleep quality and addictive behavior when young health sciences students use smartphones. This implies the need to teach or develop strategies to prevent or minimize the negative consequences of the chronotype on mental health and its effects on production. Educational activities on sleep hygiene strategies, the healthy use of smartphones taking into account the chronotype in health sciences students, are needed in order to benefit mental health offuture healthcare professionals. p p p p p p p p p p p p p
