1
Department of Global Research, Ritsumeikan University, Kyoto, Japan
2
The graduated University of Advanced Studies, Miura, Japan
Corresponding author details:
Mitsu Nakamura
The graduated University of Advanced Studies
Miura,Japan
Copyright:
© 2018 Nakamura O, et al. This
is an open-access article distributed under the
terms of the Creative Commons Attribution 4.0
international License, which permits unrestricted
use, distribution and reproduction in any
medium, provided the original author and source
are credited
The experience of our environment stimulates our perception and our ability to learn.
This learning ability is enhanced by the quality and duration of our sleep [1-3]. Recent
results have shown that repetitive stimuli influence cortical neuron responses and their
mechanisms of synaptic plasticity, as well as their learning and consolidation process
during sleep [3]. It is easy to see why sleep disorders such as insomnia, narcolepsy and
sleepwalking; are continually associated with cognitive or memory deficits. This reality can
occur as much in healthy subjects as in mental health, as in individuals with diagnoses of
neurological disorders such as Parkinson’s or people with depression [4]. Sleep disorders
may be the result of a neurological disorder (anxiety, depression and dementia) or an
early stage neurodegenerative disease (Parkinson’s disease and Alzheimer disease) [5-8]
or be the cause of brain imbalance (cognitive impairment or decreased alertness). Among
the sleep disorders that best characterize this cerebral dysfunction, we find insomnia
(e.g. frequent awakenings, maintenance of difficult sleep, early awakening) and excessive
daytime sleepiness (e.g. sleep attacks, frequent sleepiness during the day). These sleep
disturbances have multifactorial and varied causes (e.g. pathophysiology of Parkinson’s
disease, medication, co-morbidities such as cognitive disorders and psychiatric disorders)
[8]. Stress is a determinant of sleep disorders. We distinguish environmental stress,
which is the result of exposure to multiple environmental stressors (e.g. housing, income,
presence of a caregiver) that varies according to socioeconomic status and psychological
stress causing certain disorders mood (anxiety, depression) [8]. In the elderly, the level of
exposure to environmental stressors influences psychological stress. Hypothetically, there
is thus a strong relationship between environmental stress and sleep disorders, but also
between environmental stress and mood disorders such as depression and anxiety. Thus,
several external factors (environmental and socio-economic) and psychobiological factors
(hormones, circadian cycle, lifestyle, medical history, medication) act on sleep disorders.
The literature has recently shown the individual effects of each category of factors
mentioned above, on sleep disorders and cognition. But the combined interaction of the
two types of factors has been little, or never studied. The current literature also describes
several processes and diseases in the elderly population and arising from the influence of
psychobiological, environmental and socio-economic factors [8-10]. Yet, there is still a lot
of data on cognitive impairment and sleep disorders in young adults, who are subject to
the same factors. The prevalence of sleep disorders is significantly higher in the population
aged 50 and over. This state of affairs is correlated with the processes accompanying
the aging of individuals. The predisposing factors are numerous and contribute to the
progressive trajectory of neurodegeneration and co-morbidities in the elderly [11-13]. The
lack of favourable terrain in young adults suggests a lack of neurological disorders, or in
other words a minimization of the effects of environmental and psychobiological factors on
the cognition and somnopathies of young adults. It is therefore important to understand the
simultaneous effect of socio-environmental stimulation and psychobiological profile on the
evolution of sleep disorders in this young adult population.
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