originally written for and published on Harkla
SENSORY PROCESSING AND DEEP TOUCH PRESSURE (DTP)
Sensory Integration is the process your central nervous system goes through when it takes information in from the environment and your body’s eight senses, processes that information, and then responds accordingly.
Your body takes information in through 8 sensory systems: auditory (sound/hearing), olfactory (smell), gustatory (taste), tactile (touch), vestibular (movement),
proprioceptive (input from muscles and joints), and interoception (internal sensors indicating physiological conditions).
When one’s central nervous system has difficulty processing any of this sensory information, the body’s responses are atypical and can be observed in motor, language, or social-emotional difficulties.
Deep pressure or deep touch pressure therapy (DTP) is firm tactile sensory input that provides proprioceptive input to the whole body. This can consist of firm hugs, firm strokings, cuddling, hugging, squeezing, compression,or swaddling. When administered to the whole body, deep touch pressure therapy (DTP) has a calming, organizing effect on children and adults alike.
PHYSIOLOGICAL RESPONSES TO DEEP PRESSURE THERAPY
When considering your body’s physiological responses to sensory information, and your own emotional reactions, you need to consider the 3 different parts of your Autonomic Nervous System (ANS) and how those systems work together to help you function.
The autonomic nervous system is responsible for receiving information from your body and environment, and sending signals out to regulate the functions of many of your body’s organs in response to that information. Think about the last time you were nervous - sweaty palms, racing heartbeat, fast breathing, and maybe even an upset stomach. On the other hand, think about how you relax every night as you drift off to sleep - slow, deep breathing, slow heart beat, relaxed muscles. All of those physiological responses came from your functioning autonomic nervous system. The ANS is comprised of the parasympathetic, sympathetic, and enteric (gut) systems. Depending on the sensory information your ANS is processing, these systems work together to help you physiologically respond.
The parasympathetic system of your autonomic nervous system is responsible for regulating involuntary functions like heart rate, blood pressure, and stimulating the digestive tract. Deep touch pressure increases this parasympathetic activity and helps slow many high energy functions of the body, thereby helping with regulation.
The sympathetic system of your autonomic nervous system is often referred to as the “fight or flight” response that is elicited during stressful or emergency situations. Think of the adrenaline rush you experience when you’re in an accident or come across a dangerous situation. That is your sympathetic ANS at work! Deep touch pressure decreases this “fight or flight” sympathetic activity and decreases the level of cortisol (stress hormone) which is hugely impactful for people who experience stress, anxiety, or fear on a regular basis (anxiety, PTSD, dementia, ASD).
Deep touch pressure also results in increased endorphin levels and releases the “happy hormones” serotonin and dopamine. Serotonin is a neurotransmitter that helps to regulate some brain functions and help with mood regulation. It is also known to stimulate parts of the brain that are responsible for sleep and the production of melatonin. Dopamine is a “happy hormone” that controls the reward or pleasure center of the brain. While it regulates our emotional responses and is in action when we set or achieve goals, an excess of dopamine is also linked to risk taking and addiction.
At a physiological level, deep pressure therapy helps the two main systems in the autonomic nervous system balance each other out so as to help with emotional regulation. The increased production of serotonin and dopamine counteract the effects of cortisol to hormonally regulate your body’s response to sensory information.
RESEARCHING DEEP TOUCH PRESSURE (DTP)
There have been a number of studies that look at the effects of deep touch pressure, dating back to the original work of occupational therapist and neuroscientist Dr. Anna Jean Ayres, who was a pioneer in the field of Sensory Integration theory and framework. In recent decades, Temple Grandin has contributed significant insight, her own research, and development of the “Hug Machine” for DTP therapy. When looking at the research, the products and procedures may differ but the type of sensory input (weighted blankets versus weighted vests versus compression vests) the studies are investigating are all deep touch pressure sensory inputs.
A 2011 study published in the Journal of Medical and Biological Engineering found the physiological effects of Deep Touch Pressure (medical data like heart rate, blood pressure, etc) corresponded with the participants’ reportedly lower anxiety levels following weighted blanket use. The study’s data validated a change in nervous system activity after deep touch pressure (weighted blanket) was introduced. Since we know that people who experience sensory overstimulation experience real physiological symptoms, this study supports that deep touch pressure can help regulate those medical changes.
In a 2008 study published in Occupational Therapy in Mental Health, use of a 30-lb weighted blanket (deep touch pressure) resulted in adult participants reporting lower anxiety (63%), lower physiological data (blood pressure, pulse rate, pulse oximetry), and positive calming effects (78%). Weighted blanket use in mental health settings, proactively and in crisis situations, had a calming effect that was reported to lower stress and provide a coping strategy in times of anxiety. The use of weighted blankets has been expanded to include people with mental health diagnoses like post-traumatic stress disorder, ADHD, anxiety, and obsessive compulsive disorder. Study participants reported feeling safe, calm, and grounded following weighted blanket use.
Deep pressure compression products like the My T Jacket and Snug Vest have conducted their own trial studies to support the efficacy of their products. Participants included in the first clinical trial were preschool-aged children with identified sensory modulation dysfunction and autism spectrum disorder. Results of this T Jacket 2017 study found that 83% of participants showed improved seated behavior while wearing the T Jacket (uninflated) and 60% of those same participants showed improved seated behavior when the T Jacket was inflated.
The Snug Vest trial study looked at observable effects of deep pressure compression on children with autism spectrum disorder and/or sensory processing disorder. The data showed a decrease in anxiety, tantrums, meltdowns, and tactile defensiveness, and an increase in positive emotions after the vest was inflated.
There have been a number of studies that support the effects of deep touch pressure therapy and more resources can be found at the end of this article, should you want additional information!
OBSERVABLE EFFECTS OF DEEP PRESSURE THERAPY
Functional outcomes of deep pressure therapy are observed as:
Improved proprioceptive processing for increased balance
Improved body/spatial awareness