During recent decades, experts in the field of education have focused on cognitive processes, such as attention performance. Attention is considered one of the most critical and higher-order activities of the mind and one of the prime characteristics of cognitive structure playing a significant role in the structure of intelligence, memory, and perception
[1]. The process of attention plays several roles, including the determination of the kind of required information for processing, control of unnecessary information, manipulation of the current information, and reliability of processing for an extended period
[2]. Through the regulation and prioritization of stimuli that are processed by the central nervous system, attention acts as the gatekeeper of the mind. One of the influential factors in cognitive functions, such as memory and attention, is rapid eye movement sleep
[3].
Sleep is regarded as one of the significant needs of human beings and is among the physiological needs with regard to Maslowʼs hierarchy of needs. Quality sleep occurs when an individual falls into a deep sleep; therefore, quality sleep is something more than finding a chance to sleep for a few hours
[4]. When an individual becomes older, the main changes occur in his/her sleep pattern, structure, and quality bringing about sleep disturbances and consequent frequent complaints
[5]. Nevertheless, sleep disorder occurs in all age groups, and it is estimated that one-third of adolescents experience sleep problems
[6]. Sleep disorders (e.g., inadequate sleep, poor quality of sleep, and irregular sleep)
can influence cognition, emotions, and motor development and bring about physiological changes in the brain
[7]. In addition, disturbances in the sleep and waking cycle can affect the feeling of exhaustion and lack of concentration
[8].
Circadian rhythms are considered a part of biological rhythms, which are a set of constant biological activities, and their duration and amplitude are statistically significant. They are repeated at least during two consecutive periods
[9, 10]. Furthermore, the impact of the gravity of the moon has produced a tide that can even control reproduction [11]. Based on their cycle duration, biorhythms are divided into several categories, including ultradian (less than 20 h), circadian (within 20 and 28 h), and infradian (more than 28 h)
[12]. The proof of the existence of these internal clocks is that if an individual is placed in an environment with constant light and temperature
[13].
Sleep and waking rhythms are the primary factors in creating chronotype or individuals’ preferences during periods of sleep and waking
[14]. As a result, individuals can be classified under two types, namely morningness and eveningness
[15]. These individual differences are genetic and are created based on the endogenous biological clock
[16] and influenced by the environment
[17]. Numerous studies have revealed that generally morningness is more frequently observed in children and adults
and eveningness is more commonly noticed in adolescents
[18].
Regarding the cognitive processes and optimal performance time, various studies have compared the two above-mentioned groups. In a study, morningness, in comparison to eveningness, showed higher memory performance even when subjects were tested in the morning
[19]. In addition, in another study, short-term memory performance was superior in the morning than that reported in the evening. Furthermore, the impact of circadian rhythm is taken into account as a mediating factor in the psychological field and it can be suitable for cognitive activities, attention capacity, and memory function and lead to the deterioration or enhancement of performance
[20]. A circadian pattern regulates memory function, and the peak of performance in short-term memory in the morning group occurs early in the morning and in the evening group occurs during the early hours of the night. The idea of different circadian rhythms shows that functional biological clocks exist in both of the rights and left hemispheres of the human brain
[21] and independently function in diverse situations
[22-24].
On the other hand, emotion is one of the variables influenced by circadian rhythms and sleep quality. Debarnot et al.
[25] demonstrated that there is a relationship between circadian preferences and personality characteristics of impulsivity and emotionality. Tapia-Osoria et al.
[26], in their study on rats, observed that disorder in circadian rhythms, which is resulted from being exposed to 8 weeks of nonstop light, deteriorates the suprachiasmatic nucleus and causes depressive and anxiety-like behaviors. Berger et al.
[27] showed that the despoiled pattern of circadian rhythms was accompanied by anxiety-provoking tiredness and depressive symptoms. The impact of weekly rhythms on performance has revealed that the early days of the week were associated with minimal temperament, arousal, and workload, and the day before the weekend had different results
[28-33].
Objectives
This study was conducted to determine the mediating role of emotional processing styles in
the relationship between sleep quality, lateral superiority, and circadian rhythms with attention performance.
Materials and Methods
This fundamental descriptive-correlational study was carried out on all the undergraduate psychology students of Islamic Azad University, Islamshahr Branch, Tehran, Iran, (n=2,300) using a stratified random sampling method. Firstly, the total number of the statistical population was determined; secondly, the number of the first-, second-, third-, and fourth-year students in each subgroup was determined; thirdly, after the determination of the sample size, the ratio of each subgroup was estimated and multiplied by the sample size. Finally, it was determined that how many students were needed in each subgroup. The inclusion criteria were an age range of 20-40 years, no psychological illness, conscious consent to participate in the study, and at least a bachelorʼs degree. The exclusion criteria of the study were incomplete responses to the study questionnaires.
Morningness-Eveningness Scale (Circadian Rhythm Scale)
This scale is a 19 multiple-choice self-assessment questionnaire developed by Horne and Ostberg in 1976 to determine an individualʼs circadian rhythm type. The scores are within the range of 17-76. A higher score indicates a higher level of morningness, and a lower score shows a higher level of eveningness. In numerous studies, it has been reported that this questionnaire has adequate internal consistency. The internal consistency of the questions was within the range of -0.02 to +0.61, with a mean of +2.2. Furthermore, the Cronbachʼs alpha of the questionnaire was reported as 0.77
[34].
Lateral Superiority Evaluation Checklist
This checklist was developed by Chapman
[35] and included 13 items extracted from the best materials of valid questionnaires. The answers to each item are specified based on the selection of one of three options, including right hand (score 1), both hands (score 2), and left hand (score 3). As a result, the scores are within the range of 13 (perfectly right-sided) to 39 (perfectly left-sided). Individuals with scores within the range of 13-17 are categorized as right-handed (right-dominant), and those with scores within the range of 18-39 are classified as left-handed (left-dominant) and ambidextrous. The internal consistency and retest reliability of this scale were reported as 0.96 and 0.97, respectively. In addition, the correlation of this scale with a behavioral assessment of hand lateral superiority was 0.83. The reliability of this questionnaire using Cronbachʼs alpha, split-half, and test-retest were 0.94, 0.94, and 0.92, respectively
[35].
Pittsburgh Sleep Quality Index
This instrument was designed by Boyce et al. in 1989. This 9-item questionnaire is employed to measure the quality of sleep over the past month. Items 1 and 3 are essay items, and the rest are multiple-choice items. The total score of this questionnaire is within the range of 0-21. A score of 0 to 4 indicates the desired quality of sleep, and a score of 5 or higher shows the poor quality of sleep. This questionnaire includes seven components, namely subjective sleep quality, sleep latency,
sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The reliability of the Persian version of this index was reported as 0.89
[36].
Emotional Processing Scale
This scale was developed by Bakker et al. in 2007 and is a 38-item self-report scale that is used for the measurement of emotional processing styles. Each item is scored on a 5-point Likert scale (never: score 1 to almost always: score 5). Therefore, in this scale, the minimum and maximum scores are 38 and 190, respectively. The scale has eight subscales, namely intrusion, suppression, lack of attunement, lack of
control, disassociation, avoidance, discordance,
and externalization. The items related to each component are 1-8 (intrusion), 9-12 (suppression), 13-17 (lack of attunement), 18-21 (lack of control), 22-25 (disassociation), 26-28 (avoidance), 29-35 (discordance), and 36-38 (externalization). The coefficients of Cronbachʼs alpha and test-retest reliability of this scale were 0.92 and 0.79, respectively. Moreover, the Cronbach’s alpha coefficient of this scale was reported as 0.95
[37].
D2 Selective Attention Test
This test measures the degree of focus (i.e., selective attention) based on the spectrum of general functions. The d2 test puts the subjects in front of the task of selecting visual target stimuli from an assembly of different visual stimuli that are culturally independent. In order to measure the internal consistency of d2 test scales, various external studies have been conducted in different statistical societies. All of the coefficients in these studies, including Spearman and Guttman split-half methods and Cronbachʼs alpha, were higher than 0.90, indicating very high reliability of the scales of the d2 test
[38, 39].
In the present study, two types of descriptive and inferential statistics were employed to analyze the data. Firstly, the values of descriptive statistics (i.e., frequency, percentage, mean, standard deviation, and minimum and maximum scores) regarding the characteristics of the sample and variables under study were determined, and then the structural equation modeling and SmartPLS software (version 3.2.9) were employed to analyze data.
Results
Demographic information included the age and gender of the participants. Firstly, the frequency distribution of the variable of gender in the present study was investigated.
Table 1 shows that 48% (n=96) and 52% (n=104) of the respondents were male and female, respectively.
In examining the study hypothesis, it was shown that emotional processing styles played a mediating role in the relationship between circadian rhythms, lateral superiority, and sleep quality with attention
performance (Table 2). Therefore, it can be said that circadian rhythms, lateral superiority, and sleep quality with a coefficient of 35% (confidence level=0.95; t-value=2.382) affected attention performance with the presence of the mediating factor of emotional processing styles (Table 3).