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Occupational Therapy in Mental
Health
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Exploring the Safety and
Therapeutic Effects of Deep
Pressure Stimulation Using a
Weighted Blanket
Brian Mullen BS a , Tina Champagne MEd, OTR/L b ,
Sundar Krishnamurty PhD a , Debra Dickson APRN, BC
b & Robert X. Gao PhD a
a University of Massachusetts—Amherst, Department
of Mechanical & Industrial Engineering—ELAB
Building , 160 Governors Drive, Amherst, MA, 01003,
USA
b Cooley Dickinson Hospital, Acute Inpatient
Behavioral Health Department , 30 Locust Street,
Northampton, MA, 01060, USA
Published online: 08 Sep 2008.
To cite this article: Brian Mullen BS , Tina Champagne MEd, OTR/L , Sundar
Krishnamurty PhD , Debra Dickson APRN, BC & Robert X. Gao PhD (2008) Exploring
the Safety and Therapeutic Effects of Deep Pressure Stimulation Using a Weighted
Blanket, Occupational Therapy in Mental Health, 24:1, 65-89, DOI: 10.1300/
J004v24n01_05
To link to this article: http://dx.doi.org/10.1300/J004v24n01_05
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Exploring the Safety and Therapeutic
Effects of Deep Pressure Stimulation
Using a Weighted Blanket
Brian Mullen, BS
Tina Champagne, MEd, OTR/L
Sundar Krishnamurty, PhD
Debra Dickson, APRN, BC
Robert X. Gao, PhD
ABSTRACT. This paper presents the results of a concurrent, nested,
mixed methods exploratory study on the safety and effectiveness of the
use of a 30 lb weighted blanket with a convenience sample of 32 adults.
Safety is investigated measuring blood pressure, pulse rate, and pulse
oximetry, and effectiveness by electrodermal activity (EDA), the State
Trait Anxiety Inventory-10 and an exit survey. The results reveal that
Brian Mullen (E-mail: Bmullen@student.umass.edu), BS, is Graduate Research
Assistant, Sundar Krishnamurty (E-mail: skrishna@ecs.umass.edu), PhD, is In-
terim Department Head and Associate Professor, and Robert X. Gao (E-mail:
Gao@ecs.umass.edu), PhD, is Professor; all are at University of Massachusetts-
Amherst, Department of Mechanical & Industrial Engineering–ELAB Building, 160
Governors Drive, Amherst, MA 01003 .
Tina Champagne (E-mail: Tina_Champagne@cooley-dickinson.org), MEd, OTR/L,
is Occupational Therapy and Group Program Supervisor, and Debra Dickson (E-mail:
Debra_Dickson@cooley-dickinson.org), APRN, BC, is Behavioral Health Clinical
Nurse Specialist; both are at Cooley Dickinson Hospital, Acute Inpatient Behav-
ioral Health Department, 30 Locust Street, Northampton, MA 01060.
Address correspondence to Tina Champagne at the above address.
The authors wish to acknowledge and thank the UMASS-Amherst School of Nursing
for providing use of the nursing lab and vital signs monitoring equipment for the pur-
poses of this study and to Dr. Keli Mu for his assistance with the revisions of this paper.
Occupational Therapy in Mental Health, Vol. 24(1) 2008
Available online at http://otmh.haworthpress.com
© 2008 by The Haworth Press. All rights reserved.
doi:10.1300/J004v24n01_05 65
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the use of the 30 lb weighted blanket, in the lying down position, is safe
as evidenced by the vital sign metrics. Data obtained on effectiveness
reveal 33% demonstrated lowering in EDA when using the weighted
blanket, 63% reported lower anxiety after use, and 78% preferred the
weighted blanket as a calming modality. The results of this study will be
used to form the basis for subsequent research on the therapeutic influ-
ence of the weighted blanket with adults during an acute inpatient mental
health admission. doi:10.1300/J004v24n01_05 [Article copies available for a fee
from The Haworth Document Delivery Service: 1-800-HAWORTH. E-mail ad-
dress: <docdelivery@haworthpress.com> Website: <http://www.HaworthPress.
com> © 2008 by The Haworth Press. All rights reserved.]
KEYWORDS. Sensory modulation, weighted blanket, deep pressure
touch stimulation, skin conductance, electrodermal activity
INTRODUCTION
The weighted blanket is a therapeutic modality used within the scope
of occupational therapy practice (Nackley, 2001; Walker & McCormack,
2002). It has been increasingly employed in acute mental health care
settings for crisis intervention, preparatory purposes, and as a purposeful
activity, which appears to help the consumer nurture, soothe, and care
for himself or herself (Champagne & Stromberg, 2004). When used in
this way it is considered a sensory modulation treatment tool aiding in
the stabilization and recovery process (Champagne, 2005). While there
is no published research on the safety or effectiveness of the therapeutic
use of the weighted blanket, anecdotal accounts support that when used
in an individualized manner, the weighted blanket appears to facilitate
the ability to feel safe, comforted, and grounded in the world (Cham-
pagne & Stromberg, 2004; Heller, 2002).
The President’s Freedom Commission (Department of Health and Hu-
man Services, 2003) was initiated to promote a national focus on increas-
ing options in the areas of treatment, education, employment, assistive
devices, and universally designed technology for people with mental ill-
ness. National and state mental health organizations, such as the National
Association for State Mental Health Program Directors (NASMHPD)
and the Department of Mental Health (DMH) support this initiative and
advocate the use of more humane, person-centered, and sensory sup-
portive options (Huckshorn, 2004; National Executive Training Institute
[NETI], 2003). Although it is well established that no one therapeutic
tool is helpful to all consumers, the use of the weighted blanket as a
66 OCCUPATIONAL THERAPY IN MENTAL HEALTH
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prevention and/or crisis intervention tool, classifies as a primary and
secondary crisis prevention approach (NASMHPD, 1999), which may
ultimately help to decrease the need for the use of restraint and seclusion
(Champagne & Stromberg, 2004; NETI, 2003). Therefore, given the
potential of this humane and recovery supportive treatment option and
the importance of engaging in evidence-based practice, it is necessary
for occupational therapists to begin studying the safety and effective-
ness of the use of the weighted blanket.
Further, when requesting the allocation of resources to introduce a
novel treatment modality into clinical practice it is necessary to present
empirical evidence demonstrating that its use is within one’s scope of
practice and that it is both safe and effective. This may be achieved
through the application of principles from traditional social science and
engineering data analysis. Such an analysis will not only lead to a better
understanding of the therapeutic effects of deep pressure, but also will
lay the foundation for technological advances in the remote sensing of
anxiety (Luharuka, Gao, & Krishnamurty, 2003), and the engineering
of new and improved modalities offering deep pressure stimulation. To
this end, this paper presents the details of the first clinical study exploring
both the safety and effectiveness of the use of a 30 lb weighted blanket, the
heaviest available at the time of the study, with a heterogeneous conve-
nience sample of 32 volunteer adults.
Background Information
Deep Pressure Stimulation (DPS)
One of the qualities offered by the weighted blanket is DPS, which is
generally referred to as a form of touch pressure applied to the body
providing the feeling of a firm hug, holding, swaddling, or massage
(Grandin, 1992). Although there is no published research regarding the
use of the weighted blanket, there is a growing body of research sup-
porting the use of DPS for varied therapeutic purposes. Interestingly,
when using Grandin’s Hug Machine, the use of DPS had a calming in-
fluence for adults and children with anxiety, autism, and attention dif-
ficulties (Edelson, Edelson, Kerr, & Grandin, 1999; Grandin, 1992).
Additionally, DPS applied through the use of the weighted vest, for chil-
dren with pervasive developmental and attention disorders, influenced an
increased ability to focus on fine motor tasks (Fertel-Daly, Bedell, &
Hinojosa, 2001; Olson & Moulton, 2004a, 2004b; VandenBerg, 2001),
and a decrease in self-stimulatory behaviors (Fertel-Daly et al., 2001).
Mullen et al. 67
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Foam-padded splints to the arms applying firm pressure appeared to help
reduce self-stimulatory and self-injurious behaviors in a child with au-
tism (McClure & Holtz-Yotz, 1991). Wrist weights providing DPS influ-
enced a reduction in self-injurious behaviors by 92% in a child with
intellectual disabilities (Hanley, Piazza, Keeney, Blakeley-Smith, &
Worsdell, 1998). These studies provide support for the use of DPS mo-
dalities for a variety of treatment purposes, such as the facilitation of
attention, self-control, and a decrease in anxiety. While providing some
evidence of the effectiveness of the use of DPS modalities these studies
do not specifically explore the use of the weighted blanket or whether the
modalities used are safe.
Measuring Safety and Establishing Guidelines
Safety guidelines established for the use of backpacks have been gen-
eralized to the use of the weighted vests and weighted blankets (Olson &
Moulton, 2004a; Walker & McCormack, 2002). This includes recom-
mendations according to body weight ratios (5-10%), the distribution of
the weight, and wearing schedules. Weighted vests are typically used
while in ambulatory and/or seated positions, whereas the weighted blan-
ket is not meant for use while ambulating. Rather, the weighted blanket is
used while in a lying down or seated position. Therefore, applying the
same backpack safety guidelines to the use of the weighted blanket is
unsubstantiated. Further, clinical experience of the authors suggests
that for some consumers the use of a weighted blanket that is more than
10% of the person’s body weight may be preferred. Hence, there is a
need to explore whether the use of the 30 lb weighted blanket has a neg-
ative influence on physiological safety and whether there are patterns or
preferences according to body weight. Vital signs provide information re-
garding a person’s general health status and are used in this study to begin
to assess whether the deep pressure provided from a 30 lb weighted blan-
ket influences adverse changes in the vital signs of the test participants.
Measuring Effectiveness
Mixed research methodology, the use of a combination of quantitative
and qualitative approaches, is considered a reliable way to measure the
effectiveness of therapeutic interventions (Creswell, 2003). Edelson et al.
(1999) used a mixed methods approach to explore the influence of DPS
provided by Grandin’s Hug Machine on the anxiety levels of children
with autism using the Connors Parent Rating Scale and electrodermal
activity (EDA). Skin conductance (SC), a measure of EDA, provides a
68 OCCUPATIONAL THERAPY IN MENTAL HEALTH
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direct measure of sympathetic activity and has been one of the most
widely used quantitative metrics in psychophysiology research (Boucsein,
1992; Cacioppo, Tassinary, & Bernston, 2000). Although only a mar-
ginal reduction in anxiety was revealed using SC, a significant decrease
in tension (a behavioral measure of anxiety) occurred, and researchers
concluded, “deep pressure appears beneficial for children with high lev-
els of anxiety or arousal, and there may be a threshold of anxiety or
arousal required for deep pressure to be beneficial” (Edelson et al., 1999,
p. 151). Krauss (1987) examined the influence of DPS among college
students using a self-controlled mechanical device to self-administer
DPS with a pulley system, using qualitative surveys and body tempera-
ture to monitor anxiety. Temperature is also a measure of sympathetic
arousal (Boucsein,1992). Although the results from Krauss’ study were
found to be inconclusive, these studies demonstrate the value of the
use of mixed methodology, including psychophysiological metrics in
addition to subjective self-report, when studying the influence of DPS.
Evidence demonstrates that sympathetic arousal is directly linked to
emotional and other cognitive processes such as attention, decision-mak-
ing, and memory (Damasio, Tranel, & Damasio, 1991; Damasio, 1994;
Bechara, Tranel, Damasio, & Damasio, 1996; Bechera, Damasio,
Tranel, & Damasio, 1997; Cahill, 1997). Further, chronic high levels
of sympathetic arousal are hallmarks of anxiety disorders and stress,
which are conditions associated with high levels of psychological and
physical morbidity (Russek, King, Russek, & Russek, 1990; Steptoe,
Cropley, & Joekes, 1999). It has also been demonstrated that treatments
influencing the reduction of autonomic arousal often reduce anxiety and
distress (Critchley, Melmed, Featherstone, Mathias, & Dolan, 2001).
Thus, it is hypothesized that the weighted blanket assists in helping con-
sumers decrease anxiety and levels of distress. Since SC is a direct mea-
sure of sympathetic nervous system activity, which is influenced by
anxiety, SC is a quantitative measure used to explore effectiveness. The
State Trait Anxiety Inventory-10 (STAI-10) and an exit survey are self-
rating metrics, also used to explore effectiveness.
METHOD
Experimental Design
A concurrent, nested, mixed methods design was used to gather quan-
titative and qualitative data. The qualitative data gathering process was
Mullen et al. 69
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embedded within the quantitative procedures. Figure 1 shows the ex-
perimental design.
Sample
A convenience sample of 34 people including 20 males and 14 fe-
males participated in the study. Testing was interrupted for two partici-
pants; therefore, the data for these two participants were not included in
the statistical analysis or results. Consequently, the final sample size of
the study was n = 32. The age range was 18-58, with a mean of 31 and a
standard deviation of 11.7. The population was skewed toward younger
people because a large number of the volunteers were undergraduate
and graduate students. The lowest body weight of the participants was
112 lb and the maximum was 234 lb with a mean of 165 lb and a standard
deviation of 27.8 lb. Inclusion criteria required consenting, non-hospi-
talized, volunteer adults with no apparent medical conditions or physical
70 OCCUPATIONAL THERAPY IN MENTAL HEALTH
FIGURE 1. Experimental design overview.
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injuries between the ages of 18 and 64. Because this was an exploratory
study, a diverse group of people participated. It is understood however,
that age, sex, weight, and race may have varying influences on psycho-
physiological processes and responses.
Using random assignment and a cross over design the participants
were divided into two groups, each person receiving an even or odd
code and number designation. All persons participated in two-test ses-
sions, one session with the treatment (the 30 lb weighted blanket) and
one session without the treatment. The code the person was assigned de-
termined whether the treatment was given during the first or second
testing session. An even code required the use of the treatment (30 lb
weighted blanket) during the first testing session, an odd code required
use of the treatment during the second testing session. Before any testing
or data collection occurred age, sex, and weight were recorded and all
participants signed an informed consent document. The informed consent
document explained potential risks or harm that could arise from being
a participant in the experiment, provided a general summary of the in-
struments to be used, and also the procedures that would take place
throughout the course of the experiment. Before starting the experiment,
the participants were each individually introduced to the test environ-
ment, room, and equipment, and the procedures of the experiment were
thoroughly explained. Questions were encouraged and answered before
the volunteers were asked to sign the consent form. Being fully informed
helps to reduce uncertainty regarding the testing procedures; otherwise,
the novelty of the experience may influence the test responses.
Setting
The study was conducted at the nursing resource room at Skinner
Hall at the University of Massachusetts-Amherst (UMASS). Two nurs-
ing resource rooms were set up to replicate a hospital-like setting, which
was determined to best afford a relatively controlled environment, al-
lowing for comparisons to be made in future studies conducted in an
acute mental health care hospital setting. Hospital beds with pull cur-
tains were used to seclude participants from the monitoring equipment
and most of the stimulation of the rest of the room. During the experi-
ment, the resource room door was locked, a sign was placed on the door
to inform the public that an experiment was taking place, and only the
participant and data collector were allowed in the room. Before the data
collection phase of the test session, the curtain was closed around the
bed; the data and all the equipment connected to the sensors were behind
Mullen et al. 71
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the curtain and out of view of the participant. The room temperatures
ranged between 72⬚and 75⬚Fahrenheit.
Procedures
Grandin (1992) reported the need to use 5 minutes of sustained DPS
to produce a calming influence with children. Anecdotally, the authors
have noticed that the influence is often observable within minutes of use
with adolescent-, adult-, and geriatric-populations in acute care mental
health settings. For the purposes of this initial exploratory study, 5-min-
ute time frames with and without the treatment were used. The partici-
pants were given a 5-minute break between testing sessions where they
were required to complete a STAI-10 survey and leave the testing area.
The data collection equipment was set to have no alarms or noises and
remained quiet throughout the monitoring phases. All participants were
tested in the lying down position. Blood pressure was monitored on
the right upper extremity and all pulse oximetry, pulse rate, and SC data
were collected from the right hand. To ensure the consistency of proce-
dures and data collection throughout the experiment for all participants,
data collectors used a standardized data-recording protocol document and
practice sessions.
Instruments
The Treatment: The Weighted Blanket
One 30 lb weighted blanket was located at each of the two experiment
stations. The weighted blankets used in this study were 56 inches ⫻76
inches in size and each blanket weighed 5 lb in itself (with all of the
weights removed). The blankets were each set up to contain five addi-
tional (removable) 5 lb sleeves of nylon material filled with popcorn
seed, each running the length of the blanket and securely buttoned into
place. Velcro secured each of the openings around the edge of the blan-
ket. The additional five weighted sleeves served to provide an addi-
tional 25 lb of weight in an evenly distributed manner throughout the
blanket. Thus, each blanket weighed a total of 30 lb. The blankets used
in this study were purchased from Weighted Wearables and ordered spe-
cifically to be consistent in make/style, materials used, and weight. This
was carefully specified and subsequently verified by the researchers.
72 OCCUPATIONAL THERAPY IN MENTAL HEALTH
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Quantitative Measure of Safety: Vital Signs
For the purposes of this initial study exploring safety, the following vi-
tal sign metrics were used: pulse oximetry, pulse rate, and blood pressure.
Each participant’s vital signs, data with the blanket and without the
blanket, were compared for each vital sign measured in order to deter-
mine if the blanket influenced a change in vital signs. Table 1 shows the
safe ranges of the vital signs for adult populations, when in an upright
position (Barkauskas, Baumann, & Darling-Fisher, 2002). There are no
standardized vital sign parameters available for the lying down position;
thus, the information in Table 1 was used as a general guideline. It is well
established however that blood pressure and pulse rate decreases when
someone is lying down (Barkauskas et al., 2002).
Vital signs were obtained using a GE 4000 vital signs machine
(Model # DSH04490805GA). Pulse oximetry (SpO2) is a measure of
the amount of oxygen concentration in the blood. It is measured by plac-
ing a probe onto a person’s finger. The SpO2reading is also known as
the oxygen saturation level and is recorded as a percentage. The normal
SpO2range is from 90 to 100% in adult populations (Barkauskas et al.,
2002). Pulse rate indicates the number of times the heart beats per minute.
The anatomy and physiology of the blood pressure “is the interaction of
the cardiac output and peripheral resistance and is dependent on the ve-
locity of the arterial blood, intravascular volume, and the elasticity of the
arterial walls” (Barkauskas et al., 2002, p. 175). There are normal varia-
tions that can occur with a person’s blood pressure. Typically the first
reading is higher than others and at least one to three minutes should be
left between readings for accuracy. An average of readings over time
affords the best indication of an individual’s baseline blood pressure
(Barkauskas et al., 2002).
Mullen et al. 73
TABLE 1. Vital Signs Parameters
Age Temperature Pulse
per/min
Respirations
per/min
Oximetry
Spo2
BP Systolic
(mm Hg)
BP Diastolic
(mm Hg)
Adult 98.6 ⫹/⫺1 60 to 100
(Mean 75)
12 to 20 90 to 100% 100 to 130 60 to 85
Adapted from: Harkreader, H. and Hogan, M. A. (2004), and Barkauskas, Baumann, and Darling-Fisher
(2002).
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Quantitative Measure of Effectiveness:
Electrodermal Activity (EDA)
The effectiveness of the 30 lb weighted blanket is measured using
EDA, the STAI-10, and an exit survey. EDA continuously changes over
time and influences the increased or decreased activity of the eccrine sweat
glands, and is measured through the collection of SC (Stern, Ray, &
Quigley, 2001). Hence, for the purposes of this study, SC is used as the
quantitative indicator of anxiety. Skin Conductance (SC) is obtained us-
ing the ProComp⫹SC sensor from Thought Technology, using a con-
stant-voltage sampling of SC at a rate of 32 hz with an accuracy of ⫾5%.
Silver chloride cup electrodes were used to minimize the development of
bias potentials and polarization. The electrodes were secured to the volar
surfaces of the first and second distal phalanges of the right hand of each
participant, using Velcro fasteners. Since the results will be compared,
10% accuracy is used as the significance level, because, when comparing
the control group to the treatment group, it is possible that one of the read-
ings may have an error of ⫹5% and the other by ⫺5%.
RESULTS
Vital Signs Analysis and Interpretation
For the purposes of this study, a negative influence in vital sign mea-
sures concludes that the use of the 30 lb weighted blanket is unsafe for the
participant. When the vital sign measures remain within the participant’s
normal range it is concluded that the treatment is generally safe. Not
taken into consideration during this initial exploration of the safety of
the use of the 30 lb weighted blanket include additional safety factors
related to medical conditions not experienced by the participants (e.g.,
fractured bones, open wounds, circulatory disorders, pregnancy).
The safety results, as evidenced by the three vital signs metrics used,
are shown in the following sections. The ending values are analyzed
closely because the end of the 5-minute test sessions shows the accumu-
lated influence of the blanket use. The recorded values of the vital signs
data during the sessions without the blanket were used as a baseline. The
baseline data were compared to the data collected when the blanket
was used to determine if the blanket is the cause of the participant be-
ing within an unsafe range. A baseline is necessary since some of the
74 OCCUPATIONAL THERAPY IN MENTAL HEALTH
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participants may naturally be outside of the safe ranges at their baseline
or because of some other unknown contributing variable.
Pulse Oximetry (SPO2)
Only 20 of the 32 participants were included in the pulse oximetry
analysis because of sensor attachment problems during data collection.
Table 2 shows the initial and final SPO2measurements for 20 participants
with complete sets of data collected, both with and without the blanket.
None of the participants shown in Table 2 have a final oxygen level be-
low 90%. Thus, there is no evidence to show that the weighted blanket
causes any adverse affects to the amount of oxygen in the blood.
Pulse Rate
As shown in Figure 2, none of the participants have a final pulse rate
greater than 100 beats per minute with or without the blanket. There are
seven participants whose pulse rates are under 60 beats per minute, with
and/or without the blanket. Of the participants with a pulse rate below
Mullen et al. 75
TABLE 2. Pulse Oximetry Results
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60 beats per minute, only one person’s pulse rate with the blanket is
below his/her control value without the blanket. This suggests that those
participants may normally have a pulse rate outside the general safe range
and that the weighted blanket was not the cause of the pulse rate being out
of the safe range.
Blood Pressure (BP)
The volunteer’s initial and final BP is averaged to account for the
variation in BP as discussed in the introduction. On average, all partici-
pants are found to be at the low end of the safe range. Only one participant
has an average BP, in either of the 5-minute test sessions, in the high end
of the safe range. Participant #2 has a high BP average. Upon further ex-
amination of this participant’s data, however, 3 of the 4 readings were
on the low end of the safe range. Only the first BP reading was high and
out of the safe range. Participant #2 had the blanket applied during the
first test session; the BP right before the blanket application was 150/89.
BP dropped to 121/76 by the end of the test session and was 124/77 and
125/72 for the beginning and end of the second test session, respectively.
Since the blanket was applied during the first session and the BP was high
before the blanket was applied, the high BP could have been a result of
76 OCCUPATIONAL THERAPY IN MENTAL HEALTH
FIGURE 2. Pulse rate results: Each participant’s pulse rate after 5 minutes
of testing with the weighted blanket (squares) and without the blanket (dia-
monds).
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anxiety caused by participating in the experiment. Thus, the conclusion
should not be made that the blanket caused participant #2 to have an av-
erage BP out of the safe BP range over the test session.
Figure 3 shows the average systolic and diastolic BP for each person
with and without the blanket. The bold horizontal lines denote the safe
range over the course of the study. This figure shows that all but partici-
pant #2 were inside the safe range for the BP guidelines for systolic blood
pressure. The majority of the participants were toward the lower end of
the safe range for the average diastolic BP.
In sum, it can be concluded that the data from the three different vital
sign measures collected show that the use of the 30 lb weighted blanket
did not cause the participants to move into an unsafe physiological range.
All 20 participants stayed above 90% for SPO2, all 32 participant’s pulse
rates stayed below 100 beats per minute and only one participant’s pulse
rate with the blanket was below his/her control value without the blanket.
Only one person was out of the safe range for systolic BP, which could
be attributed to anxiety from participating in the experiment, and not to
the blanket. No participant was outside of the safe range for diastolic BP.
The data give no evidence to indicate that the use of the 30 lb weighted
blanket is unsafe.
Mullen et al. 77
FIGURE 3. Average diastolic and systolic blood pressure for each participant
with the blanket (squares) and without (diamonds) the blanket.
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EDA Data Analysis and Interpretation
Data interpretation is a critical step in the scientific study of the time
series data gathered using SC. It requires a standardization procedure that
ensures the integrity of information contained in the raw data in a consis-
tent and uniform manner. Accordingly, this study introduces one such
procedure to address the lag time effects related to sensor amplification,
the uncertainty associated with the response starting and ending times,
and the influence of external factors such as the curtain is closing and
opening affecting the responses. Specifically, to overcome the inherent
drawbacks by using the raw data, the SC recordings were extended in
this study to both before and after the actual test duration of 5 minutes.
Additionally, the actual start time was identified as the time at which
there was a noticeable drop in the SC reading caused by movement be-
fore the person was considered to be settled into the rest position, and
the corresponding SC reading at this start time was taken as the average
of the data up to that time. Figure 4 shows a sample time-series data and
the identification of the resulting 5-minute actual test session for further
data analysis.
Skin Conductance (SC) Results
Two of the 32 participants were dropped from the anxiety data analysis
because of problems with the SC sensor during their test sessions. Table 3
shows the mean values for the whole sample, the blanket first sample,
and the blanket second sample, as well as the standard deviation. The per-
cent change in the SC data is examined to study if there is a difference be-
tween using the blanket and not using the blanket. This percent change
acts as the indicator of how much change occurs over the 5 minute pe-
riod, taking into account different starting values by normalizing the
data. The average percent changes in Table 3 show that regardless of
blanket order or test session, SC values decrease significantly over time
indicating that the lying down position influences a reduction in anxi-
ety. When examining each person’s response, 27 of the 30 participants
have a decrease in SC over both of the 5 minute test sessions.
Table 4 shows the comparison of percent change in SC between
participants over a period of 5 minutes. To compare the participants’
responses, the percent change with the blanket is subtracted from the
percent change without the blanket for each person. If the resulting
number is negative then the person had a larger percent change in SC
without the blanket than with the blanket. Ten of the 30 participants
78 OCCUPATIONAL THERAPY IN MENTAL HEALTH
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demonstrated a significantly larger drop in SC when using the blanket
than when not using the blanket. Four of the 30 participants showed an
increase in SC with the blanket compared to when not using the blanket
and 16 participants had no significant difference between the two test ses-
sions.
Table 5 shows the results from performing a Student’s T-test assuming
unequal variance comparing “with the blanket” to “without the blanket”
sample populations. T-tests were also used to compare the blanket ap-
plied to the first group to the blanket being applied to the second group.
The results from the statistical analysis show that there is no significant
difference between using the blanket and not using the blanket, and there-
fore, no difference between the orders in which the blanket was applied,
with an alpha of 0.05.
A z-test is also conducted for the entire sample because of the neces-
sary assumption of having more than 30 participants to assume normal-
ity. The results shown in Table 6 reveal a statistically significant result
Mullen et al. 79
FIGURE 4. Example of the GSR level data with the landmarks of participants’
adjustment period and curtain close time, and the 5-minute time span of testing
window.
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when comparing “with the blanket” and “without the blanket,” having
an alpha of 0.05. This verifies that there is no difference due to ordering.
STAI-10 Analysis and Interpretation
The STAI-10, a subscale of the State Trait Anxiety Inventory, is a stan-
dardized quantitative (closed-ended) 10 question survey used to measure
anxiety (Speilberger, Gorsuch, & Luchene, 1970). Data collected from
the STAI-10 were analyzed to show each participant’s self-rated per-
ception of anxiety with and without the treatment. The results were also
used in comparison with SC data for further SC validation. Since the
STAI-10 data was to be directly compared to the SC data, the two par-
ticipants who did not have SC results were not included in the analysis.
Using the STAI-10 results and comparing the scores obtained, after using
and not using the blanket, shows whether the use of the 30 lb weighted
blanket influences a larger decrease in self-perceived anxiety ratings.
STAI-10 scores and exit survey responses help to determine whether
80 OCCUPATIONAL THERAPY IN MENTAL HEALTH
TABLE 3. Average and Standard Deviation of the SC Data for the Whole Popu-
lation
With Blanket Treatment
All Participants Blanket Applied
1st Sample
Blanket Applied
2nd Sample
Mean Standard
Deviation
Mean Standard
Deviation
Mean Standard
Deviation
Initial 4.33 5.22 4.38 3.89 4.65 6.62
Final 2.65 4.21 2.47 2.46 3.07 5.70
Percent Change 38.73 20.00 43.59 18.90 33.94 21.65
No Blanket Treatment
All Participants Blanket Applied
1st Sample
Blanket Applied
2nd Sample
Mean Standard
Deviation
Mean Standard
Deviation
Mean Standard
Deviation
Initial 4.36 4.53 4.25 3.57 4.76 5.63
Final 2.79 3.53 2.54 1.95 3.31 3.28
Percent Change 35.88 22.20 41.45 23.70 30.86 21.24
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Mullen et al. 81
TABLE 4. Each Participant’s Percentage SC Change with and Without the
Blanket
Participant # WB Percentage
Change
NB Percentage
Change
Difference
(WB-2NB)
336.67 28.71 7.96
520.68 23.02 ⫺2.34
766.67 64.02 2.65
924.06 33.33 ⫺9.28
11 55.33 46.70 8.63
15 48.35 44.19 4.17
17 44.32 ⫺1.10 45.42
19 66.40 48.05 18.35
21 14.66 13.92 0.75
23 59.62 85.31 ⫺25.68
25 49.22 25.02 24.21
27 64.33 33.72 30.61
29 30.77 25.00 5.77
31 29.65 45.31 ⫺15.66
33 ⫺7.89 17.24 ⫺25.14
228.47 7.06 21.41
448.54 33.33 15.21
667.57 11.68 55.89
822.01 30.13 ⫺8.12
10 50.00 42.07 7.93
12 12.31 44.99 ⫺32.68
14 50.49 ⫺25.17 75.66
16 27.71 22.92 4.79
18 6.67 5.26 1.40
20 42.52 39.06 3.46
22 56.17 45.46 10.63
24 59.17 43.43 15.74
28 66.05 61.85 4.20
30 43.37 47.98 ⫺4.61
34 55.46 63.34 ⫺7.88
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EDA alone is a metric that correlates with the subjective ratings of the
blanket’s influence. Table 7 shows the average STAI-10 scores for the
participants. Higher scores correspond to higher anxiety ratings. On av-
erage the participants scored lower after using the blanket than without
the blanket. For the participants having the blanket applied first, the
mean STAI-10 score was 12.5 compared to a mean score of 15.7 without
the blanket in the second session. For the sample population having the
blanket applied second, the mean score was, 13.2 with the blanket and
15.3 without the blanket.
These results show that at least 33% of the sample using the blanket
had a significantly greater drop in SC or anxiety than without using
82 OCCUPATIONAL THERAPY IN MENTAL HEALTH
TABLE 5. Statistical Results from the Student’s T-test Comparison
All Participants Blanket 1st Sample
Compared to
Blanket 2nd Sample
With
Blanket
No
Blanket
t Stat 1.426 z Stat 1.401 0.302 ⫺0.479
P(T ⱕt) one-tail 0.080 P(Z ⱕz) one-tail 0.081 0.383 0.318
t Critical one-tail 1.672 z Critical one-tail 1.645 1.701 1.701
P(T ⱕt) two-tail 0.159 P(Z ⱕz) two-tail 0.161 0.765 0.636
t Critical two-tail 2.002 z Critical two-tail 1.960 2.048 2.048
TABLE 6. Statistical Comparison of All Participants with the Blanket and With-
out the Blanket
All Participants Blanket 1st Sample
Compared to
Blanket 2nd Sample
With
Blanket
No
Blanket
t Stat ⫺3.102 z Stat ⫺2.721 ⫺0.474 0.329
P(T ⱕt) one-tail 0.002 P(Z ⱕz) one-tail 0.003 0.320 0.372
t Critical one-tail 1.699 z Critical one-tail 1.645 1.725 1.701
P(T ⱕt) two-tail 0.004 P(Z ⱕz) two-tail 0.007 0.641 0.744
t Critical two-tail 2.045 z Critical two-tail 1.960 2.086 2.048
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the blanket, and 53% of the sample experienced no difference when
comparing the blanket condition and the no-blanket condition. It was hy-
pothesized that only a portion of the tested participants would respond to
the blanket with a reduction in anxiety, particularly given that it was a
low anxiety population as evidenced by the initial STAI-10 question-
naire results. Grandin (1992) specifically indicated that there might need
to be a threshold anxiety before DPS will be effective. Also, given that
the population is non-acute and, by lying down for 5 minutes anxiety lev-
els dropped greatly, it may be possible that participants reached their
steady (minimum anxiety) dynamic state or baseline SC so that the
blanket could not reduce SC levels much further.
From the STAI-10 survey data collected, there were 19 participants
whose anxiety decreased more with the blanket, 8 participants experi-
enced no change, and 3 had higher anxiety with the blanket than with-
out. Comparing the STAI-10 data to the SC data in Table 8, it seems that
SC accurately indicated the participant’s perceived change in anxiety
when the use of the blanket resulted in higher anxiety than without the
blanket. This raises the question as to why the SC data did not match the
STAI-10 survey data. Since the SC measurements indicated when the
anxiety of the participant was higher with the blanket and not for when
the anxiety was lower with the blanket suggests that by lying down for
5 minutes the participants reach their baseline SC even though anxiety
continues to decrease. For some participants using the blanket, the blan-
ket influences an activating response and raises the SC above baseline
so the effects could be seen.
Exit Survey Analysis and Interpretation
In addition to STAI-10 data, the exit survey questions were analyzed
to explore each participant’s responses regarding the use of the weighted
Mullen et al. 83
TABLE 7. Average STAI-10 Data for All Participants with the Blanket and With-
out the Blanket
STAI-10 All Participants Blanket 1st Sample Blanket 2nd Sample
Mean
Blanket Applied 12.87 12.53 13.20
No Blanket Applied 15.50 15.73 15.27
NB-WB 2.63 3.20 2.07
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blanket, personal preferences, and whether the self-reports matched the
STAI-10 and SC results. When asked, “when did you feel more relaxed,
when using the blanket or when not using the blanket?” 25 of the 32 par-
ticipants (78%) reported that they felt more relaxed with the blanket than
without the blanket.
The exit survey included the question, “how did the amount of weight
feel?” with three choices to choose from: too much, not enough (I would
like it heavier), and good. Table 9 explores if there is a relationship be-
tween body weight and preference for a 30 lb weighted blanket. Only
one person reported that the 30 lb weighted blanket was “too much,”
and, given the variability of body weight among the participants, body
weight did not appear to significantly influence the person’s preference
regarding the 30 lb weighted blanket.
Additionally, the participants were asked to rank their preferences ac-
cording to four of the qualities afforded by the weighted blanket using a
Likert scale [ranking very effective (1) through very ineffective (5)].
These qualities include: the warmth of the blanket (temperature), the
weight of the blanket (30 lb/deep pressure), the feel of the fabric (tactile),
and that it was voluntarily used (not forced upon the participant). Table 10
shows the varied responses.
Finally, to the question “any other comments about the SC or weighted
blanket?” Ten participants commented on the use of the blanket, and all
were positive comments. When comparing the SC data for these ten
particular participants, four had a larger percent change in SC with the
blanket, four had a larger percent change in SC without the blanket, and
two had no change.
84 OCCUPATIONAL THERAPY IN MENTAL HEALTH
TABLE 8. Statistical Comparison of the Group with the Blanket and Without the
Blanket
STAI-10 Skin Conductance
Greater Change
With Blanket
Greater Change
Without Blanket
No
Change
Total
Greater change with blanket 7 3 9 19
Greater change w/o blanket 1 1 1 3
No change 2 ⫺68
Total 10 4 16 30
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DISCUSSION
Limitations
There are several limitations in this study. One limitation is that only
a 5-minute time frame was used in each of the test sessions; therefore,
results cannot be generalized to the use of the 30 lb weighted blanket for
longer time periods. Second, since one of the primary purposes of the
study was to research safety, participants were all required to use the
full 30 lb. When using the weighted blanket in clinical practice it is part
of the protocol to individualize the amount of weight used and the pre-
ferred weight placement. Hence, different results may be obtained with
the individualization of the amount of weight used. Third, the pulse
oximetry and SC sensors did not stay in place for all of the participants;
therefore, not all participants’ pulse oximetry, pulse rate, and SC data
were obtained. Fourth, there may be a difference in the results if the group
without the blanket used a thin sheet rather than no sheet or blanket at
all. Fifth, there is an absence of well-established mathematical models
to characterize SC data without the use of other physiological measures
such as respiration, though general guidelines have been put forward
Mullen et al. 85
TABLE 9. Deep Pressure Stimulation (DPS) Self-Report
DPS of the 30 lb. Weighted Blanket Number of Responses Body Weight Ranges
“Not enough” 5 112 -234 lbs.
“Good” 26 114 -206 lbs.
“Too much” 1 174 lbs.
TABLE 10. Weighted Blanket Qualities: Participant’s Self-Ratings
Weighted Blanket Qualities
Participant’s Rankings
Very
Effective (1)
(2) (3) (4) Very
Ineffective (5)
Warmth (Temperature) 12 15 3 1 1
Weight (Deep pressure) 13 15 2 2 0
Feeling of the fabric (Tactile) 11 11 7 2 1
Voluntarily used (Not forced
upon you)
10 13 7 1 1
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using parameters such as number of SC peaks and their corresponding
values (Boucsein, 1992). Thus, it is possible that the development and
subsequent use of empirical models, through additional dynamic and
statistical analysis of data, may provide more insight into the influence
of the use of the weighted blanket. A final limitation includes the use
of a low-to-no anxiety population, while according to Edelson et al.
(1999), a threshold of arousal or anxiety may be necessary to influence
SC changes when using modalities providing DPS. The low anxiety
contributed to the physiological signal to seemingly reach a floor during
the 5-minute test sessions.
Implications and Recommendations
This paper presents the results of a first exploratory study on the
safety and effectiveness of the use of a 30 lb weighted blanket among
a heterogeneous, non-hospitalized volunteer sample. A general proto-
col using quantitative and qualitative metrics was piloted to determine
whether it would be useful in future studies on the safety and effective-
ness of the weighted blanket. This research group will conduct these
studies with both an adult population during an acute inpatient mental
health hospitalization and a non-acute, volunteer adult population sub-
jected to a high anxiety task.
The results of this study demonstrate that the use of a 30 lb weighted
blanket did not adversely influence pulse oximetry, pulse rate, or blood
pressure. Further, using SC as an anxiety metric, 33% of the participants
were found to exhibit a greater reduction in anxiety with the weighted
blanket than without the blanket. Observations however, reveal that there
appear to be differences in the results. The corresponding STAI-10 sur-
vey responses showed that 63% of the participants rated their anxiety
lower with the use of the weighted blanket. Furthermore, according to
the exit survey, 78% reported a lower anxiety after using the blanket
than when not using the blanket. Thus, the results indicate that the use
of the 30 lb weighted blanket has a calming influence for some adults.
For many participants, the perceived sense of relaxation is greater
than indicated by SC measures. This may be a result of some of the partic-
ipants’ reaching a SC floor as a sole result of lying down for 5 minutes.
Further research comparing additional psychophysiological metrics
more sensitive to changes in anxiety, in conjunction with SC, may en-
hance the ability to more accurately measure anxiety through the use
of quantitative measures. Future studies looking at correlations among
SC, DPS, age, sex, race, sensory tendencies, consumer preferences, and
86 OCCUPATIONAL THERAPY IN MENTAL HEALTH
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diagnostic factors is recommended to continue exploring the safety and
effectiveness of the therapeutic use of the weighted blanket. Re-
search is needed to explore other aspects of safety, such as the use of the
weighted blanket with people with different medical conditions. Addi-
tionally, future research may afford the ability to gain knowledge of how
to engineer new technologies in the remote sensing of anxiety, and new
DPS devices specific to people’s unique needs and preferences.
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doi:10.1300/J004v24n01_05
RECEIVED: 05/03/06
REVISED: 11/02/06
ACCEPTED: 12/08/06
Mullen et al. 89
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