The University of Massachusetts Amherst
University of Massachusetts Amherst

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Soothing High Anxiety with a "Huggable Blanket"

Everyone knows the soothing effect of going home after a hard day and burrowing under your blankets. A mechanical engineering student at the University of Massachusetts Amherst did her senior honors thesis on a new kind of “weighted blanket” designed to soothe patients with high anxiety resulting from autism or mental illness. Lexington resident Marnie Bonner created her “deep pressure touch simulation (DPTS) device” after surveying 25 healthcare professionals about the pros and cons of five weighted blankets already on the market. Her new model, which is still in the development stage, combines the best attributes of all five devices into a “huggable blanket” that gives people with anxiety disorders a comforting embrace.

The idea of weighted blankets isn’t new. They have been used for several years, offshoots of the original ``hug machine" designed by Dr. Temple Grandin, an autism patient herself who got the idea from pressure chutes that calm down cattle.

“So she developed one for herself and found that it made her calm down,” explains Bonner. “And after that, other modalities were started, including weighted vests, weighted blankets, wrist weights, weighted animals, squeeze machines, and pressure vests.”

The most commonly used DPTS modality is the weighted blanket. However, there is a lack of evidence-based research in the field of DPTS therapy and the use of the weighted blankets. As a result, they have not always proven to be dependable, safe, cost-effective, or meeting the needs of either patients or caregivers.

Most suppliers of weighted modalities provide only anecdotal evidence that they work. ``There hasn't been any scientific study on why does it work, what makes it work, is it safe and effective?" says Professor Sundar Krishnamurty, who is Bonner’s faculty advisor in the UMass Amherst Mechanical and Industrial Engineering Department. Dr. Krishnamurty’s team used the results of Bonner’s research in the development of doctoral student Brian Mullen’s Deep-pressure Vest, which works on the same principle as weighted blankets and won the $50,000 UMass Amherst Innovation Challenge last May. Krishnamurty’s team also plans to use Bonner’s research to develop a pressurized sleeping bag that takes portable hugging to a new level.

To create her own hug machine in a scientific way, Bonner surveyed the professionals who actually use weighted blankets so she could find out their best and worst qualities in clinical settings. Amanda Worcester also helped Bonner with her survey. Occupational therapist Tina Champagne and registered nurse Debra Dickinson, both of Cooley Dickinson Hospital in Northampton, Massachusetts, were crucial to the advancement of this project. They not only found the participants and blankets to be used in the survey, but spent many hours helping Bonner understand and apply her mechanical engineering knowledge to the field of nursing.

“It was great working with these healthcare professionals because they gave me as an engineer a perspective I wouldn’t have thought about,” says Bonner. “For example, one blanket had these long stringy weights that could be used by people in a psychiatric ward to strangle themselves. Or other blankets have weights made from things like buckshot and plastic that would be bad for patients if they tore open a blanket and ate the stuff. Or another consideration is whether removable weights could be used as weapons.”

Each blanket differed by manufacturer, color, fabric, heaviness, pattern, fill composition of the weights, and whether or not the weights were removable. The survey was administered at the University of Massachusetts Amherst, University of Massachusetts Medical Center Worcester, and Cooley Dickinson Hospital. Participants included occupational therapists, registered nurses, rehab aids, social workers, psychiatric counselors, and clinical specialists. Many of those surveyed had experience with various DPTS modalities. Potential health hazard was a major concern, as various participants rated some blankets unsafe due to their potential for strangulation, abuse, and/or smothering.

Based on her research and analysis of weighted blankets, Bonner developed a final design that meets the customer needs as well as the ideal target specifications indicated by the survey.

“Many of the problems happened because blankets were designed for autistic children and their needs,” notes Bonner, “while now they’re being used in psychiatric wards for a variety of illnesses, where there is a whole different set of needs.”

The new design is a plush washable cover, composed of a layer of batting in between two layers of thick fabric. The cover comes with snaps to accommodate four flat weights, a quarter-inch thick, that are filled with poly pellets and covered with medical grade vinyl. The weights snap into the blanket in between its two outer layers, which are then sealed together with Velcro.

“I really did enjoy that research because it shows how mechanical engineers can go into almost any field, and how useful they can be for humanitarian causes,” Bonner says. “Anything has to be engineered originally.”
UMass Amherst alumni Michael and Theresa Hluchyj established a summer research initiative in 2008 between the College of Engineering and the School of Nursing that provided Bonner with the necessary financial support to carry out the survey. Bonner’s research also led to an internship with the Pratt & Whitney company last summer, working on low cycle fatigue in the discs of jet engines, and to a fulltime job at the company after her graduation in May. (February 2009)