Abstract—This study presents evidence of the chronotype’ significant influence for the cognitive performance of children aged between 7 and eleven years old, specifically for the attention skills. Two groups of children were identified regarding their chronotypes: morning, intermediate and eveningn types. The impact of chronotype or diurnal preference was examined concerning the performance in attention subtest of Wechsler Intelligence Scale for Children (WISC). The subtest was administered in two periods of the day – morning and afternoon - during two weeks. The students answered to the same subtest with one-week interval. The statistical analysis for the chronotype identification (through questionnaire) and for the attention test (WISC) followed the procedures and the score calculation of the original version of the instruments. By using the SPSS, version 24, were carried out comparison statistical tests to confirm performance differences. The different biological preferences of children impacted the attention fluctuation in a significant manner (p< .05) considering the different hours of tests realization which confirmed that biological clocks are determining and affecting the synchrony effect: the optimal performance according to specific periods of the day. These specific periods are determined biologically and with differences among individuals. Even determined biologically, the chronotype shows variation during lifespan. The results of this study highlight the crucial reflexion for the biological studies on the diurnal preferences and their impact in life of human being. Specifically related to Psychology area in order to understand the effect of biological rhythms in the development of young children and the schedules of the assessment settings where they are assigned.

Index Terms—biological rhythms, school children, sleep patterns, cognitive performance, daytime preference

Cite:Sandra Figueiredo, Odete Nunes, João Hipólito, and Cátia Tomás, "Sleep Habits and Biological Clocks Determined in Children: Cognitive Fluctuations and Intelligence," International Journal of Pharma Medicine and Biological Sciences, Vol. 8, No. 3, pp. 114-117, July 2019. doi: 10.18178/ijpmbs.8.3.114-117