1. Comorbidity of Depression and Insomnia Caused by Common Factors
Jennifer K. Ocasio Adorno

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Abstract
Comorbidity between insomnia and depression is a common problem that is affecting a certain
number of the United States population in a negative manner. The incidence of this comorbidity
is not a coincidence and cannot be considered as one. Factors such as common dysfunction of
the hypothalamic-pituitary-adrenal axis (HPA axis) and cerebral cortex hyperarousal hint at a
link that ties the two together. Using a functional Magnetic Resonance Imaging (fMRI), the link
of these two conditions could be found. This link is essential in the proper treatment of this
comorbidity and could be useful in future studies.

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Introduction
Insomnia usually precedes depression and makes a person 9.8 times mores susceptible to
developing depression. Given that depression affects approximately 10-15% of the United States
population, the comorbidity presented in these two disorders poses many problems to a great
quantity of people. Depression for one, poses many health risks such as suicidal risk. Insomnia,
which affects 30-35% of the population, is equally as problematic, causing excessive fatigue that
could prove fatal in a given situation. Although thought to be psychiatric disorders, both of these
conditions pose health risks and can be considered actual medical conditions. Both insomnia and
depression have aspects in common rooted in actual medicine. They both show dysfunction of
the HPA axis, leading to increased activity of corticotrophin-releasing factors (CRF) and cerebral
cortex hyperarousal.
The high incidence of both of these diseases appearing one after the other and the
similarities that present themselves give rise to a very important conclusion: the comorbidity of
insomnia and depression is caused by a common link. Although insomnia could be regarded
only as a symptom of oncoming depression, the presence of a relationship between the two is a
much more substantial conclusion. Therefore, my objective is to determine if there does, in fact,
exist a link between the two. If this link is found to exist, steps can then be taken to find a more
universal treatment for the onset of both, one that could better target the actual problem and not
just the symptoms.

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Methodology
Before any measures can be taken to actually discern the possible relationship in the
comorbidity of insomnia and depression, permits must first be obtained from the Institutional
Review Board (IRB) to be able to work with humans. Once permits have been successfully
obtained, a survey must then be made and distributed to patients from cooperating institutions
that have demonstrated depression, insomnia or both. This survey will have key questions
concerning the patient including basics such as age, sex and other such information. Besides
this, it will also include questions concerning the actual health of the person, for example:
Has anyone in your family demonstrated depression or insomnia?
Have you ever had insomnia or depression?
The answers to the surveys will then be evaluated and a select group of approximately
300 people will be chosen. This sample will be divided evenly into four groups with an
approximately equal number of both men and women, each with 75 people. The first group will
be a control of healthy individuals who have not shown signs of either disorder and have not had
any inclination towards them in their family history. The second group will be comprised of
people that have only demonstrated signs of insomnia and have not developed nor ever
demonstrated symptoms of depression. The third group will have adults that have only shown
symptoms of depression and have not had an incidence of insomnia beforehand. The final group
will be comprised only of people who have both insomnia and depression.
Using Magnetic Resonance Imaging (MRI), or more specifically, a functional MRI
(fMRI), brain activity of the population chosen will be observed. These results will be compared
among the groups, using the healthy individuals as a control to exclude any activity that it not
related with the actual disorders. The similarities will then be processed and studied using the

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MRIs to determine if the relationship of the comorbidity does, in fact, exist. If it does, then
further steps must be developed to find the root cause of this with the hopes that in the future, a
more universal and specific treatment could be developed to treat the incidence of these two
disorders.

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