Happy Memorial Day weekend to our friends in the states! What better way to spice up your weekend, than to learn more about deep pressure stimulation – more specifically a compression vest and how it attenuates the effects of stress on the body!
Many of our posts discuss deep pressure stimulation from the perspective of the autonomic nervous system, why is the autonomic nervous system so important and, better yet, what is it? I’m so happy you asked!
The autonomic nervous system is responsible for our unconscious bodily processes such as breathing, heart rate, and sweating. It is comprised of two branches: the sympathetic nervous system, and the parasympathetic nervous system. The sympathetic nervous system is responsible for our fight or flight response, so when it is heightened, it is safe to assume there is a stressor which in turn causes our mind/body to be on high alert.
On the contrary, the parasympathetic nervous system is known for its rest and digest properties- meaning, when activated, the parasympathetic nervous system slows down the heart rate, and relaxes muscles to promote tasks such as digestion. When the parasympathetic nervous system is heightened, it is safe to assume we are in a more calm, cool, and collected state.
With this description, you can see why the autonomic nervous system activity has been measured to detect shifts in physiological arousal (effects of stress on the body). Data collected from the shifts of the autonomic nervous system give us insight into the effects of stress on the body and how a compression vest can impact them.
In previous studies which we have dissected, the researchers have used the autonomic nervous system as a variable to measure anxiety with deep pressure stimulation, but the ailments that are triggered by high sympathetic activity extend farther into other presenting concerns such as attention-deficit/hyperactivity disorder, autism, or post-traumatic stress disorder. In fact, a lot psychological conditions can be traced back to the effects of stress on the body; it all boils down to stress.
By tapping into the mechanisms of action with sensory integration therapy (such as deep pressure stimulation in various applications) and the autonomic nervous system, interventions can become standardized and thus provide relief to more people over time.
Let’s take a look at what we know – how sensory integration therapy interactions with the brain.
Compression Vest Study
Reyolds, Lane, and Mullen (2015) sought to better understand autonomic responses in adults utilizing a compression vest. Rather than studying anxiety itself, Reynolds et al., (2015) broadened their results to the effects of stress on the body, which can be applied to various diagnoses, such as those listed above.
Who Wore the Compression Vest for this Study?
A normative sample comprised of 50 adults between the ages of 18 and 35 were recruited to participate. Normative samples are awesome, because they give us excellent insight as to how an intervention/ treatment method will impact the general population.
Gender Breakdown of Participants
To participate, each individual could not:
- Be pregnant.
- Have cognitive/ intellectual delays or motor impairments
** Although, if you are looking for a study that addresses cognitive/ intellectual impairments, check out this one)** Spoiler alert: they found similar results to this study.
About ¼ of the sample recruited were being treated for mental health ailments – fear not though, this better replicates an overall population.
How were the Effects of Stress on the Body Observed?
Data were collected within a dimmed room, and participants were fitted into a deflated compression vest.
Data Collection Sequence
Participants had two electrodes applied to their body (chest and back) to collect heart rate and respiration data. Also, an electrode was attached to their palm to collect skin conductance data.
Skin conductance data measure autonomic activity – more sweat = more stress. Heart rate and respiration are also a way to detect autonomic activity – higher heartbeat/ breathing rate = more stress.
During the phase which entailed use of the compression vest, participants self-inflated their vests to the desired pressure. It would be interesting for the researchers to also have collected data on pressure preference for each participant in order to aid in the development of standardization for clinical use. However, I’m not aware of any way that this data could be collected, due to the differences in body shapes and sizes, and vast difference in preferences.
Each stage lasted for three minutes exactly. The researchers chose three-minute increments based on anecdotal evidence, however, previous studies have used at least five minutes, and Temple Grandin (1992) has noted that up to ten minutes may be needed for benefits to occur, but her device was primarily used on children. It has been noted that children need longer durations of deep pressure stimulation to notice changes/ benefits. Regardless, I can’t help but wonder how the results would have differed had the researchers opted for longer phases.
The “test” stage was comprised of various brain buster activities and was used to purposely heighten sympathetic activity, so that the researchers could test if the compression vest would decrease sympathetic activity/ increase parasympathetic activity.
Can a Compression Vest Reduce the Effects of Stress on the Body?
Skin conductance data was at its lowest when the compression vest was used. Less sweat = Less sympathetic activity.
Skin Conductance Shifts
Nonspecific skin conductance response was lowest when the compression vest was used. Non-specific skin conductance in similar to skin conductance in that it tested for arousal during each phase of the experiment.
Changes in Nonspecific Skin Conductance
Respiratory sinus arrhythmia (RSA) was highest during compression vest use, which indicates there was an increase in parasympathetic response increased. RSA is different than regular heart monitoring in that it accounts for the increase in heart rate during inhalation, and thus looks at the heart rate cycle during inhalation/exhalation as a whole.
Respiratory Sinus Arrhythmia Shifts
There was a reduction in errors between test 1 and test 2. This information can be interpreted in various ways: (a) the compression vest helped reduce anxiety, and thus performance increased, (b) attention increased, thus allowing participants to better focus on questions.
Shift in Errors Between Tests
There were no significant differences between genders for any of the data collected.
DeBriefind From Our Author
Due to the baseline periods of three minutes being implemented after the stressor, I wonder if parasympathetic activity actually increased due to the vest, or did it increase naturally from time and the removal of the stressor, however, there was a jump in parasympathetic activity between the compression vest and baseline 3, so this may negate my skepticism.
I am stuck on the idea that the data would have looked different had the phases been longer than three minutes. Also, to ensure that it was, in fact, the vest that was causing shifts and not time, another phase of vest use would have been helpful.
The results from this study support previous data that we have examined, thus providing more evidence that deep pressure stimulation itself has an impact on autonomic activity regardless of the method used. To date, we have not explored an inflatable vest, but only weighted apparatuses, so this gives another point of view in regards to deep pressure stimulation.
I hypothesize that this intervention would serve well in populations with PTSD, as it may be an effective way to decrease sympathetic activity, and therefore allow the client to process trauma in a safe setting and move closer towards the completion of treatment goals.
Grandin, T. (1992). Calming effects of deep touch pressure in patients with autistic disorder, college students, and animals. Journal of Child and Adolescent Psychopharmacology, 2(1), 63-71. doi: 10.1089/cap.1992.2.63
Reynolds, S., Lane, S., & Mullen, B. (2015). Effects of deep pressure stimulation on physiological arousal. The American Journal of Occupational Therapy, 69(3).