Espacios. Vol. 37 (Nº 25) Año 2016. Pág. 28

Relationship between sleep duration affects cognitive function in adolescents

Relación entre la duración del sueño y el desempeño cognitivo en adolescentes

André de Camargo SMOLAREK 1; Luis Paulo Gomes MASCARENHAS 1; Luis Henrique Boiko FERREIRA 1; Marcio Maciel CASCANTE-Rusenhack 2; José MONCADA-JIMÉNEZ 3; Tácito Pessoa de SOUZA JUNIOR 4

Recibido: 19/04/16 • Aprobado: 30/05/2016


1. Introduction

2. Methodology

3. Discussion

4. Conclusion



Sleep time may interfere with the ability to perform tasks requiring memory, organization and reasoning. A lack of sleep has been related to cognitive deficits; however, few studies had demonstrated an association between sleep duration and cognitive performance in South American adolescents. Therefore, the aim of the study was to determine whether a correlation between sleep duration and cognitive performance in adolescents exist. Participants from a rural school in Brazil were required to register the time they went to bed to sleep and the time they woke-up the following morning. The Stroop test was used to measure cognitive performance. Independent samples t-tests and a binary logistic regression analysis were computed. Boys went to bed a mean of one-hour later than girls (p < 0.05); however, they woke-up only a mean of 13-min later (p > 0.05). Boys slept 20-min less compared to girls (p < 0.05). Boys read more correctly than girls (p < 0.05); however, no significant gender differences were observed for reading speed and word color performance tests. A significant correlation (r = 0.12, p = 0.01) between sleep duration and cognitive performance on the Stroop test was found. In conclusion, individuals with adequate sleep duration performed better on cognitive tasks than individuals with irregular sleeping habits.
Key words: Sleep duration, cognitive impairment, Stroop Test, Adolescents.


Actualmente se han realizado distintos estudios en relación con la variable tiempo de sueño, y existen indicios de que esta puede interferir en la capacidad de ejecutar tareas que exijan memoria, organización y raciocinio. El objetivo del estudio fue verificar si existe relación entre la duración del sueño y el desempeño cognitivo en adolescentes de una escuela rural brasileira. Se contó con la participación de 54 sujetos (28 varones y 26 mujeres), con un promedio de edad de 13,7±0,9 años. Para medir el tiempo de sueño, se utilizó un cuestionario donde el sujeto debía escribir la hora a la que se fue a dormir y la hora a la que se despertó el día siguiente. Para verificar el desempeño en actividades cognitivas se aplicó el test de Stroop, el cual posee una confiabilidad de 0.89. Se realizó análisis descriptivo de los datos, además se aplicó una "t-student" no paramétrica con correlación de Levene y un análisis de regresión logística binaria con un intervalo de confianza del 95% y e. p<0,05. Se encontró una relación positiva entre la duración del sueño de los adolescentes con el desempeño en el test de Stroop (r=0.12 p=0.01). Se concluye que los individuos que presentaban una duración de sueño adecuada tienen un mejor desempeño en tareas cognitivas en comparación a individuos con hábitos irregulares de sueño.
Palabras Clave: duración del sueño, desempeño cognitivo, test de Stroop, adolescentes, raciocinio, memoria.

1. Introduction

Sleep is the subject of several studies and is considered an important variable dramatically affecting the quality of life in adolescents (Pagel et al., 2007). Sleep quantity and quality are essential for a healthy development, as well as for the interaction with society and to reactions to various stimuli adolescents experience in different environments (Gozal & Kheirandish-Gozal, 2007; Mesquita & Reimão, 2010) .

Emotional and behavioral disorders have been observed during school-age adolescents exposed to different daily situations, for instance, the period when they remain in the classroom. Since other activities are performed outside the school and involve home and actions beyond the regular school-homework, it is believed that this age group is vulnerable to functional disturbances such as school difficulties, academic failure, difficulty in the relationships with family and peers, and finally to a low self-esteem (Barkley, 2006).

When attention to satisfactorily-perform everyday tasks requiring memory, organization and reasoning is evaluated, it is found that adolescents are not always prepared to carry out these activities. Pathological and non-pathological sleep conditions are likely to affect adolescents, leaving them exposed to attention and cognitive disorders (Huynh et al., 2010) . Adolescents with attentional disorders have decreased activity in the anterior cingulate cortex (Konrad, Neufang, Hanisch, Fink, & Herpertz-Dahlmann, 2006) , the prefrontal cortex (Rubia, Smith, Brammer, Toone, & Taylor, 2005; Smith, Taylor, Brammer, Toone, & Rubia, 2006; Vaidya et al., 2005) , and the inferior frontal gyrus (Durston, Mulder, Casey, Ziermans, & van Engeland, 2006; Rubia et al., 2005) , compared to adolescents who did not have attentional disorders (Peterson et al., 2009) .

In a study (Komada et al., 2011) , it was reported that children with irregular sleep durations exhibited behavioral problems such as aggression and mainly attention deficit compared to children with normal sleep habits. Since children develop similarly to teenagers, duration and regularity of sleep patterns should be monitored by their parents so future cognitive and behavioral problems can be avoided (Bittencourt et al., 2009; O'Brien & Gozal, 2004). Therefore, the purpose of the study was to determine the association between sleep duration and cognitive performance of students from a rural school in Brazil.

2. Methodology

2.1. Participants

A purposive sample was selected for this study. Children and teenagers from the State Rural School of Lustosa, in the city of  Ipiranga, Brazil, volunteered to participate in the study. Parents and/or legal guardians signed an informed consent form to participate in the study. We recruited intentional 54 individuals, 28 males and 26 females with mean age of 13.7 ± 0.9 years.

2.2. Materials and methods

To record the time spent in bed or sleeping, we used a previously developed questionnaire in which the adolescent should write down the time (i.e., 24-hour clock format) when s/he went to bed to sleep and the time s/he woke-up (Santos, Viera & Afonso, 2009) The Stroop test (Max R Trenerry, Crosson, DeBoe, & Leber, 1989; M. R. Trenerry, Crosson, Deboe, & Leber, 1995) was used to verify the effective control and concentration. This test has been used in several populations to detect signs of cognitive dysfunction (Campanholo et al., 2014; Wagner, Müller, Helmreich, Huss, & Tadić, 2014) .

2.3. Statistical analysis

Values ​​are reported as mean (M) and standard deviation (±SD) unless otherwise noted. Frequency percentiles for the Stroop test were calculated and a tertile distribution performance was generated (i.e., low, moderate, sufficient). An independent samples t-student test with Levene's correction was computed to determine mean differences in the Stroop test. Finally, a binary logistic regression was computed to study the association between sleep duration and cognitive dysfunction. The 95% confidence intervals (CI95%) are reported. Statistical significance was set a priori at p < 0.05. Data analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 11.0.


Fifty-four volunteers participated in the study, 28 males (51.9%) and 26 females (48.1%). Descriptive statistics for the sample are shown in table 1.

Table 1. Descriptive statistics (M ± SD) for sleep time and cognitive performance for the sample studied (n = 54).






Time to bed (24-h clock, h:min)

22 ± 15

21 ± 2



Time to wake-up (24-h clock, h:min)

7 ± 55

7 ± 42



Sleep duration (min)

540 ± 39

600 ± 40



Reading performance (correct words)

111 ± 0.9

111 ± 0.7



Reading speed (s)

59 ± 0.9

56 ± 0.7



Color performance (right answers)

92.3 ±10.1

89 ± 12




Boys went to bed a mean of one-hour later than girls (p < 0.05); however, they woke-up only a mean of 13 min later (p > 0.05). Boys also slept 20 min less compared to girls (p < 0.05). Boys also read more correctly than girls (p < 0.05); however, no significant gender differences were observed for reading speed and word color performance tests. Percentile distribution figures by gender 1 and 2 show sleep, reading and color performance test variables.

Figure 1 shows that 50% of the sample has a sleep duration altered. These results may be associated to the performance in the cognitive tests. Only 7.1% of children did not do the reading test correctly; however, the performance in the word color test demonstrates the difficulty of performing a task that demands more attention, a result that may be related to school performance.

Figure 1. Percentile distribution for males on sleep, reading and word color performance test variables.

Figure 2 shows that females had disturbing results compared to males, because sleep duration was altered in 92.3% of the sample, 15.4% had errors in the reading test and 76.9% failed to achieve normal performance on the word color performance test. This group needs particular attention since the results suggest several disorders that may be associated with other serious problems.

Figure 2. Percentile distribution for females on sleep, reading and word color performance test variables.

The sleep time was significantly related to performance on the word color test, suggesting that appropriate sleep habits are essential to the phonovisual performance (Table 2).

Table 2. Correlation between sleep time and performance on the Stroop Test.


Sleep Time


Odds Ratio




Performance on the reading test



0.1 – 3.4

Time for completion of the reading test



0.1 – 1.9

Word color performance test



0.1 – 0.5


3. Discussion

The purpose of the study was to determine the association between sleep duration and cognitive performance of students from a rural school in Brazil. The main finding was that adolescents with altered sleep duration showed impaired scores in a cognitive test compared to their peers with normal sleeping patterns.

Children and adolescents are currently developing disorders like memory deficits in school activities, difficulty in planning and strategy, selective attention, and difficulty in sustaining attention in a particular activity; therefore, the use and application of neuropsychological tests are in dire need for these individuals so these disorders can be detected and treated by the appropriate specialists (Barkley, 2006).

In this study, we found a correlation between sleep duration and cognitive dysfunction. Our results are similar to other reports (Gozal & Kheirandish-Gozal, 2007; O'Brien & Gozal, 2004) , where it was found that sleep fragmentation was directly related to alterations in memory, attention and intelligence in children. The investigators indicate that a greater sensitivity of early identification and initiation of treatment of these alterations in sleep patterns can produce an improvement in cognitive performance.

The use of the Stroop Test (Max R Trenerry et al., 1989; M. R. Trenerry et al., 1995) is widespread in the literature, because this test is required to assess cognitive function in adolescents. For instance, the cognitive function performance was compared between irregular students from private and public schools (Duncan, 2006).

Research in children has shown that irregular sleep time is associated with aggressive behaviors such as attention deficit, reinforcing the hypothesis that regular sleep habits are necessary for a healthy development (Komada et al., 2011) . The authors suggest that parents or guardians must accompany their children sleep habits and in schools appropriate instruction must be given to children for a healthy good night's sleep.

Other researchers (Cho et al., 2011), have evaluated cognitive deficits in Korean children, and emphasize considering the importance of the teacher report on school performance in cognitive tests, as they assess the children's performance on activities in which predominate cognitive activities almost on a daily basis.

Sleep schedules are probably interrelated and can affect school performance and cognitive behavior in leisure activities in adolescents in public and private schools (Boscolo, Sacco, Antunes, de Mello, & Tufik, 2007). However, it is difficult to compare data between studies, as they used different protocols for data collection.

Although the quality of education is similar in urban and rural schools, they may comprise quite different skills and knowledge as witnessed by the generally higher levels of achievement of children in suburban schools compared to children in small towns or rural schools (Duncan, 2006).

4. Conclusion

In conclusion, we found a statistically significant correlation between sleep duration and performance on the word color test. Therefore, individuals having adequate sleeping times may perform better in tasks requiring cognitive components.


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1. Department of Physical Education, Universidade Estadual do Centro Oeste, Paraná, Brazil. email:
2. School of Physical Education and Sports, University of Costa Rica, Costa Rica
3. School of Physical Education and Sports, University of Costa Rica, Costa Rica; Human Movement Sciences Research Center (CIMOHU), University of Costa Rica, Costa Rica.

4. Department of Physical Education, Universidade Federal do Paraná, Brazil.

Revista Espacios. ISSN 0798 1015
Vol. 37 (Nº 25) Año 2016


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