Journal of Sleep Disorders: Treatment and CareISSN: 2325-9639

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Research Article, J Sleep Disor Treat Care Vol: 5 Issue: 4

Appropriate Sleep Duration and Physical Activity Modulate Cognitive Improvement

Etindele Sosso FA1* and Raouafi S2
1Department of Biological Sciences, University of Montreal, Quebec, Canada, Research Center in Neuropsychology and Cognition, Quebec, Canada
2Department of Biomedical Engineering, Polytechnic School of Montreal, University of Montreal, Quebec, Canada
Corresponding author : Etindele Sosso FA
Department of Biological Sciences, University of Montreal, Research Center in Neuropsychology and Cognition, Quebec, Canada
Tel: +1 514 343 6111,+ 1 819 943 0117
E-mail: [email protected]
Received: May 27, 2016 Accepted: July 19, 2016 Published: July 26, 2016
Citation: Etindele Sosso FA, Raouafi S (2016) Appropriate Sleep Duration and Physical Activity Modulate Cognitive Improvement. J Sleep Disor: Treat Care 5:4. doi: 10.4172/2325-9639.1000182

Abstract

Sleep and brain work closely and are dependent on each other. Physical exercise is now known as an efficient anti depressive for both healthy brain and cognitive decline. But few specific studies show relation between combination of these two factors and the probability to develop, when people are aged less than forty years old, cognitive impairments such as mnesic pathology, memory encoding and retrieval of information. The aim of this study is to explore how cognitive impairments are linked to sleep duration and physical exercise; and if this difference is related to sociodemographic items that we choose. This case control epidemiological study was led by a questionnaire incorporating the shorter version of McNair Test, usually employed to detect cognitive complains. The questionnaire also included ten socio-demographic items and twenty-five other questions divided in three sections: the quality of sleep, levels of physical exercise and smoking (not investigated in the present study). We recruited one hundred participants through universities in Montreal, Canada. Our results demonstrated that the stress levels are comparable in men and women. Specifically the results showed that lack of sleep combined with insufficient physical activity radically affects the cognitive score for memory, attention and MLD. The McNair score indicated that the cognitive performance decreased for all these parameters. Physical exercise and good quality of sleep including an appropriate duration, contribute both to a better cognition performance for young adults (between 18 until 40 years old) until midlife.

Keywords: Sleep duration; Cognitive parameters; Sleep; Neuroscience; Mood disorders; Brain; Cognitive impairment

Keywords

Sleep duration; Cognitive parameters; Sleep; Neuroscience; Mood disorders; Brain; Cognitive impairment

Introduction

Cerebral function is mainly improved during a delicate stage of development that is, between youth and adolescence. This important stage is characterized by creation of synapses, fine-tuning of excitatory and inhibitory neurotransmitter systems, maturation of the brain structures, and development of the nervous connections [1]. Indeed most of the brain diseases result due to variance or damage to any of these events. As a consequence of these imbalances, impairments in the perception, learning and cognitive performance of an individual may arise [2,3]. Regular, good sleep duration allows body to recover from the physical activities like sport or aerobics, and also protects individuals against neurodegenerative illness, or cognitive deficiency [4-8].
Studies have demonstrated that neuronal circuitry is fundamental to information processing in an adult brain construction, and are primarily influenced by environmental interactions, beginning at the birth until the midlife [9]. The same study also demonstrated that lifestyle factors like quality of sleep, physical exercise and nutrition in midlife have a direct effect on the probability of developing neurodegenerative illness and associated diseases later in life, inducing an impaired brain health, encompassing a range of clinical diagnosis, such as stroke, dementia, mental disorders, and cardiovascular functional impairment. The common symptoms are cognitive impairments which have increased substantially by clinician recognition, along with the support of governmental policies which support research and documentation database; and public awareness of mental disorders which has never been so higher. Variances or imbalances in timing of neuronal maturity process strongly increase the risk of cognitive impairments and most certainly leads to the development of neurodegenerative diseases, dementia, anxiety and psychiatric disorders at an unknown rate in the groups of young adults (aged between eighteen years old until midlife) [1,10-12]. Moreover, these changes also influenced the risk of Alzheimer, dementia and other associated diseases [13].
As long as no final cure for cognitive impairments exists, primary prevention of risk factors and promotion of good lifestyle are necessary, because illness and conditions related to brain health remains major aetiology of morbidity and mortality.
Physical exercise and sport were recently identified as factors with the capability to influence mental health, decreased the severity of cognitive impairments in young adult population, between eighteen and thirty-six, compared to midlife adults [14-18]. For this population we also need to acknowledge the influence of a stroke, sleep quality, and sleep disturbances or environmental stress events. Just a hand of studies explored relation between sleep duration and physical exercise with a possible impact on cognition, mental disorders and associated diseases [13,19]. Therefore, the aim of this study is to explore the link between cognitive impairment evaluated with McNair scale, sleep duration and physical exercise. We explore at the same time if this difference is related to, sociodemographic items like educational levels, medication, age and quality of sleep.

Materials and Methods

Ethics committee
This study was approved beforehand, by the ethics committee of research of the faculty of arts and science of the University of Montreal, Canada. All participants were volunteers and unknown during all the procedures of collecting data.
This case control epidemiological study was led by a questionnaire incorporating the shorter version of McNair Test, usually employed to detect cognitive complains. The questionnaire also included ten socio-demographic items and twenty-five other questions divided in three sections: the quality of sleep, levels of physical exercise and smoking (not investigated in the present study). We recruited one hundred participants through universities in Montreal, Canada. Fifty men and fifty women who received an online survey link to determine their final group between control and case. All participants were followed individually during a monthly meeting or online appointment with our questionnaire. Data collection completed over a four-month period and compiled in four different documents programmed to have no contents such as email, name, IP address or any information able to identify the responders, so totally anonymous and secured. Descriptive statistics and multivariable statistics were used to describe all closed-ended items in the test, and to sort out our results. All open-ended responses were coded using an interpretive-descriptive approach. We also used SPSS software (version 23 for windows 10, 64 bits) to perform our statistical analysis.
Cognitive parameters
Hundred respondents were assessed in subjective cognitive difficulties using a shorted version of McNair’s test of cognitive difficulties, composed of fifteen items (scored from 0 ‘never or not applicable’ to 4 ‘very often’). This version helps to evaluate cognitive complaints over the total score ranges from 0 (no difficulty) to 3 (high cognitive difficulties). The scale is composed of 4 dimensions: Attention/concentration (5 items), Language/ praxis/gnosis (5 items), and Memory Deficiency, learning disabilities and Disorders variable (5 items). We used this classification to subgroups the characteristics of cognitive complaints.
Statistical analysis
To analyse McNair test responses, we used a percentile distribution of scores. The score over 8 corresponded to a suspicious cognitive state. The relationships between socio-demographic data, stress level, sleep and cognitive complaints were tested with the U-Mann Whitney, and relation between each variable and the four dimensions of McNair were explored with Pearson’s chi-square tests. The relationships between different dimensions of cognitive complaints and MLD were examined using the test of U-Mann Whitney.
Logistic regression was carried out to assess the relationships Mc Nair’s score as a dependent variable (A) and gender and quality of sleep as independent variables. Linear regression was calculated to assess the relationships between the fourth dimensions of cognitive complaints: (Attention/concentration, language/praxis/gnosis and memory respectively) as a dependent variable (B) and gender, physical exercise and Memory Deficiency, learning disabilities (MLD) as independent variables.
Statistical tests used an alpha of 0:05 as a level of significance. Data analysis was performed using SPSS Statistics-version 23 for windows 10, 64 bits – (IBM Corporation, Armonk, NY, USA).

Results

Population characteristics
We analysed 60 subjects out of 368 sampled individuals that responded to our questionnaire in this study. To begin with, we characterized the sociodemographic items, namely: physical exercise levels, stress, sleep and cognitive parameters of the whole sample. Table 1 represented this data which is comparable to the basis on the basis of gender. By employing the McNair score (see methods), it was found that in three dimensions (Attention/concentration, language, praxis/gnosis), females scored significantly higher (p<0.001, p<0.0001 and p<0.001) than man. Notably, the memory (MLD) score was not different for both classes. It is to be underlined that, in this study, out of these 60 subjects, young adults (18–24 years) comprised 73.6% of the total population (hitherto, a high proportion). This shows that young females are better in performing cognitively than young men.
Table 1: Sociodemographic Characteristics, physical exercise, sleep duration and cognitive parameters of the total cohort according to gender.
Difference of memory score between men and women (p<0:01)
Subjective cognitive complaints, stress level and sleep duration
To begin with, the collected data were analysed with Mann- Whitney U test (Table 1). The results showed that there was a strong link between stress, physical exercise and sleep duration in relation to the gender, between the control (automatically extracted by the software) and the group under observation. The stress levels for men and women were comparable with a minor increase for men. Subjects (men and women) with less than six hours of sleep per night and less than four hours of physical exercise per week, exhibited a decrease (McNair score of thirty-five and more) of performance in three analysed dimensions (attention, language and memory). However, the performance declined substantially for men in comparison with women (p<0.001) (Table 2).
Table 2: Relationships between measures of cognitive complaints and Memory Deficiency, learning disabilities and Physical exercise disorders.
For the measures of cognitive complaints and MLD score were computed. The results showed a linear relationship between the scores of the three dimensions of the cognitive complaints and the MLD score, specifically for language/praxis/gnosis scores (linear regression, p<0.001).
Predictors of the four dimensions of cognitive complaints
As shown in Table 3, a moderate multicollinearity between independent variables (physical exercise and sleep duration) was detected (p=0.0063). The adjusted R-squared of the attention/ concentration linear regression with models ‘A’ presented 24.3% of the total variation. The relationships between measures of cognitive complaints and MLD persisted irrespective of gender (p<0.001). Subjects with attention/concentration difficulties were 2.63 times more likely to have MLD (p-value=0.004). The adjusted R-squared of the language/praxis/gnosis linear regression with model ‘B’ presented 40.6% of the total variation. Moreover, a good association between the dependent variable ‘A’ and MLD (OR=2.50, p-value<0.001) was revealed. The same association was divulged between cognitive parameters of memory and MLD (OR=4.82, p<0:01). This association with MLD was enhanced with attention impairment (OR=5.06, p<0:01). With a logistic regression based on the 75th percentile of the McNair and Kahn scale, a good association was found between this score and sleep duration. Subjects with sleep duration under 6 hours, had more than twice the chance to suffer from cognitive complaints (p<0.001).
Table 3: Predictors of attention/concentration, language/praxis/gnosis and memory scores.

Discussion

Our results demonstrated that the stress levels are comparable in men and women. Specifically the results showed that lack of sleep combined with insufficient physical activity radically affects the cognitive score for memory, attention and MLD. The McNair score indicated that the cognitive performance decreased for all these parameters.
To our knowledge, the effect of sleep has not been systematically studied in relation to the parameters employed in this investigation. Generally, previously the authors used a daily record-based approach to examine the relation between sleep quality and clinical parameters of elders participants. On the contrary, in particular, young adults (in most studies subjects were elderly) were recruited as subjects in this study. Results on elderly subjects have shown dual effect with responsibilities and multitasks professionals who regularly and intensively use their brains, and do not get enough sleep and regular exercises have a profound effect on cognitive performance [9,20-28]. Many studies were focused on pathological factors such as stroke or cardiovascular diseases that could negatively impact cognitive function, by declining attention, reducing motor reflexes, and slow capacity of performing multitask action [10,29-31], but there is some evidence of links between simultaneous actions of the pair physical exercise of participants and their duration of sleep, on the decline of cognitive function in general, or cognitive impairment in particular [32]. It has been established in the last decade physical activity is a way to reduce stress and cognitive dysfunction process [14,33-35], while a good quality of sleep and an appropriate duration of sleep perfectly ensures brains maturation and good neurocognitive function [7,36-39]. The issue is adequate data for young adult’s cognitive impairments are not present actually, and our results evoke the possibility of a positive impact of combination physical activity-sleep duration; on cognitive impairment and cognitive performance. Because people with less than eight hours of study and less physical exercise has a bad global score on McNair tests, and the four dimensions of the same scale. This study suggests, it is possible that during learning process, neuronal memory is so sensitized to the environment, here represented by the variables (A) and (B) that it is possible cognitive impairment start sooner as current epidemiological and clinical data actually indicates. We are able to detect cognitive decline with our questionnaire, if it is employed as a continuous evaluation; even with people without a cognitive diagnostic. According to our observations, a regular evaluation of cognitive performance while controlling sleep (duration and quality) and physical exercise can lead to a sensitive model of prediction.
Our questionnaire evaluated correlation between McNair scale and age, sex, duration of sleep, physical exercise. We think it will be more accurate in our next study to use a new questionnaire which explores deeply genetic history of participants and their family medical history. In addition, we will follow and record the evolution of cognitive impairments or mental status, during one year with a control every month for example [14,22,40]. Each of the above has already been studied alone or in association, to see the impact of cognitive status, psychiatric disorders and/or neurodegenerative diseases [4,7,12]. But until now, we have no evidence of the real effect of simultaneous impact of all of them, on the global mental health. We can dissociate single effect of each of these risk factors in cognition, mood disorders or neurologic symptoms. But a little hard work has to be done, to draw a final profile of the complex combination we already reported in our previous study [41].

Conclusion

Physical exercise and good quality of sleep including an appropriate duration, contribute both to a better cognition performance for young adults until midlife. Young adults and midlife samples for both men and women have almost the same level of stress but, cognitive parameters of men are more affected by this combination compared to women. Age is also a main factor because the majority of our subjects were aged between eighteen and thirty years old, and the best score was obtained by people over thirty years old. This result suggests that monitoring the mental state of young adults will considerably decrease memory complaints and prevent the onset of certain diseases of memory.

Author Contributorship

Faustin Armel Etindele Sosso work in conception and design of research, performed experiments, drafted and revised final version of the manuscript. Sana Raouafi analysed data and interpreted results.

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