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Transcript
Katherine Stones
Bio 1615 - 1pm
Final Research Paper
It is no surprise that our world today is filled with more stress, more sensory disorder,
more depression, and seemingly more of everything than even a century ago. Our world is
booming with new industry and technologies that demand our attention and keep us in
constant motion, ultimately disallowing our minds the right to recoup and recover.
Unfortunately, this onslaught of information can often lead to various mood disorders and
other such things that get in the way of fulfilling a happy, satisfied existence. I believe that
anxiety and depression will often discover each other in an individual simultaneously, and it has
been theorized that sleep disturbances are also directly involved in this mix of mood disorders.
For the last five years, I have been no stranger to all three of the aforementioned disorders, and
it is for this reason that I decided to look into a “cause and effect” research article that focused
on the troubled depression/sleep disorder relationship that seems to haunt so many.
Intro
Unipolar depression is a fairly familiar psychological disorder. Those with depression experience
feelings of low self-worth, sadness, and a lack of interest in things that they usually find
enjoyable; all of which have a conflicting effect on everyday functioning. Prevalent in both
adolescents and adults, almost 90% of those experiencing depression have comorbid sleep
disorders, thus allowing for a wide examination of their influence on the development and/or
aggravation of depressive-like symptoms.
Sleep difficulties, more often than not, seem to have a strong affinity for psychological
conditions, specifically mood disorders. The question that continues to remain unclear,
however, is whether sleep problems are a risk for the development of unipolar depression, or if
they are a result of said mood disorder. What evidence has suggested, and what seems to be
the most reasonable, is that between depression and sleep problems there is a bi-directional
relationship: each contributes to the manifestation of the other. This article’s purpose is to
examine evidence naming various sleep aspects as risk factors for depression, as well as
common underlying mechanisms and “clinical implications of the interplay between sleep and
depression.”
Methods
The authors of the article went through dozens of scientific articles and journals, which were
weeded down to only those concerning either depression or sleep difficulties, with precedence
given to studies that showed a directional relationship between the two. Studies involving the
elderly were excluded because of the additional complications not usually seen in prepubescent
individuals and young adults that could contribute to the development of sleep problems
and/or depression. Universal definitions were also given for the sake of unity in the article:
insomnia refers to the clinical condition of non-restorative sleep, sleep deprivation refers to the
purposeful elimination of sleep, and sleep disturbance refers to dysfunctions of sleep.
Results
Through studies concerning the impact of sleep deprivation on depressive symptomology, it
was discovered that sleep deprivation can either be beneficial in reducing symptoms or it can
trigger a negative mood state. Studies that have targeted and manipulated the amount of sleep
healthy participants received have shown a significant increase in depressive-like symptoms the
less sleep they get. When these same studies involved participants who were already suffering
from depression, there was generally little to no increase in anhedonia ratings. This is important
because while sleep deprivation may not cause unipolar depression, it does induce depressionlike symptoms, making it a likely risk factor
Chronic sleep disturbances, such as insomnia, have much more accumulated evidence
suggesting them as risk factors for developing depression. An area that has received much
attention is the association between childhood sleep problems and the development of
anxiety/depression in adolescence or adulthood. What was generally discovered is that the
presence of sleep problems can predict future development of unipolar depression, but the
reverse is not true. So either sleep problems are an initial symptom, or they can make an
individual more vulnerable to developing depression later in life. There also needs to be a good
amount of consideration towards the developmental aspect of sleep and depression’s
relationship, considering that sleep physiology undergoes significant changes from prepubescence all the way through adulthood.
Regulation by the prefrontal cortex (PFC) has been considered as a mechanism that
might trigger the relationship between the sleep/wake system and depression. It is involved in
both arousal control and mood regulation, as well as the regulation of affect. The orbital and
medial PFC are connected with the amygdala and hypothalamus structures in the limbic system,
and sleep deprivation is known to lead to weaker function connectivity between the two, both
of which are important for affect regulation. This suggests that impairment due to sleep
problems affects mood regulation. Furthermore, studies have indicated that impairment of the
PFC can lead directly to affective disorders, such as depression. All of this leads to the idea that
the PFC is a very likely place responsible for the co-occurrence of sleep disturbance and
depression.
The serotonergic system has also made a strong case in representing serotonin as an
underlying mechanism. Serotonin is a neurotransmitter involved in several neurological
processes that decreases in level during sleep. A study examining serotonin receptor sensitivity
discovered that sleep restriction can lead to a decreased response to the presence of serotonin,
limiting the brain’s ability to optimally use the amount of the neurotransmitter available to it.
This kind of situation had been found to be present among those suffering from unipolar
depression. There was a follow-up experiment conducted which then examined how long
desensitization lasted once the subjects were allowed some recovery sleep. But even after a
week, receptor sensitivity was still not back to normal. It is then suggested that chronic sleep
restriction can make an individual much more vulnerable to the development of unipolar
depression.
Conclusion
A good deal of the research conducted on this topic is relatively new, and there is not a solid
unity between experiments since there are many different definitions and biased opinions
regulating them. However, the theory that sleep patterns and unipolar depression are closely
interrelated cannot very easily be denounced given the huge amount of evidence provided.
Once technicalities are resolved, we can better understand the roles played by sleep
deprivation and insomnia as risk factors, the relationship between sleep problems in
adolescence compared to the development of depression in adulthood, and exactly how the
prefrontal cortex and serotonergic system can act as mechanisms in such a relationship. But for
the sake of technicalities, the relationship between unipolar depression and sleep disturbance
still remains unclear.
Discussion
I believe the authors of this scientific article did their research very well, and considered many
different outlooks on such a complicated topic. For what we know of mood disorders and sleep
problems, the information is still quite limited and we often have to make assumptions and
theories of our own (within reason) to fill in the blanks. What might have helped is if they had
more personal insight into the topic rather than completely depend on others’ already
completed studies to work with. They might have conducted tests and studies of their own in
order to determine or illuminate some of the key factors mentioned.
I chose to examine this article in particular because I wanted to better understand why
these mood and sleep disorders work the way they do and what their possible mechanisms
might be. Having dealt with depression and insomnia hand-in-hand for years, I have learned
that the more you are able to learn about them, the better you can understand not how to
control them, but how to deal with them more effectively. I found a good deal of insight into
the matter through this article and plan to look deeper into some of the topics touched briefly
here, particularly the development of depression through childhood sleep disorder symptoms.