Content uploaded by Ali Boolani
Author content
All content in this area was uploaded by Ali Boolani on Feb 05, 2019
Content may be subject to copyright.
Effect of prescribed sleep surfaces on back pain and sleep quality in patients
diagnosed with low back and shoulder pain
Bert H. Jacobson
*
, Ali Boolani, Guy Dunklee, Angela Shepardson, Hom Acharya
204 Willard Hall, Oklahoma State University, Stillwater, OK 74078, USA
article info
Article history:
Received 24 September 2009
Accepted 15 May 2010
Keywords:
Mattress
Back
Pain
Stiffness
Sleep quality
Position
abstract
The purpose of this study was to assess sleep quality and comfort of participants diagnosed with low
back pain and stiffness following sleep on individually prescribed mattresses based on dominant
sleeping positions. Subjects consisted of 27 patients (females, n¼14; males, n¼13; age 44.8 yrs SD
14.6, weight 174 lb. SD 39.6, height 68.3 in. SD 3.7) referred by chiropractic physicians for the study.
For the baseline (pretest) data subjects recorded back and shoulder discomfort, sleep quality and comfort
by visual analog scales (VAS) for 21 days while sleeping in their own beds. Subsequently, participants’
beds were replaced by medium-firm mattresses specifically layered with foam and latex based on the
participants’reported prominent sleeping position and they again rated their sleep comfort and quality
daily for the following 12 weeks. Analysis yielded significant differences between pre- and post means
for all variables and for back pain, we found significant (p<0.01) differences between the first posttest
mean and weeks 4 and weeks 8e12, thus indicating progressive improvement in both back pain and
stiffness while sleeping on the new mattresses. Additionally, the number of days per week of experi-
encing poor sleep and physical discomfort decreased significantly. It was concluded that sleep surfaces
are related to sleep discomfort and that is indeed possible to reduce pain and discomfort and to increase
sleep quality in those with chronic back pain by replacing mattresses based on sleeping position.
Ó2009 Published by Elsevier Ltd.
1. Introduction
Sleep is essential to physical, mental and emotional health. For
most adults, 7e8 h of sleep per night appears to be the ideal,
however, 75% of Americans have sleep problems during a typical
week (National Sleep Foundation, 2005). It has been estimated that
over 70 million people are currentlyaffected by sleep problems and
this number is expected to increase to over 100 million by 2050
(Reiter, 2005). Currently, the average adult gets less than seven
hours of sleep per night (National Sleep Foundation, 2005) and
such chronic lack of sleep (insomnia) affects quality of life, social
interaction and mood (Lee, 2005). Additionally, sleep deficiency
results in loss of work production, increased sick days, greater
absenteeism, loss of productivity and higher injury rates (Chilcott
and Shapiro, 1996; Drake et al., 2004; Ohanyon and Lemoinie,
2004; Godet-Cayre’et al., 2006; Hillman et al., 2006). Primarily,
stress and musculoskeletal discomfort contribute to the lack of
sleep. Typical musculoskeletal complaints that interfere with
sleeping are lower back pain and shoulder pain. A common belief is
that a firm mattress is beneficial for low-back pain, but evidence
supporting such claims is lacking. In a survey of orthopedic
surgeons 95% believed that a mattress played a part in the
management of low back pain and 75% recommended firm or hard
mattresses for the relief of back pain (Levy and Hutton, 2000). To
compound the problem manufacturers of bedding systems make
claims relative to health benefits derived from using selected
mattresses. These claims are also are largely unsupported and not
based on empirical research. Bader and Engdal (2000) found that
some mattress ads depict how the contour of the bed surface
conforms to that of the body, but they suggest that there is no
evidence that “change in spine curvature is produced while
sleeping on hard or soft surfaces”. In contrast, Lahm and Iaizzo
(2002) concluded that mattress inflation induces changes in
spinal alignment, but with no correlation in EMG activity.
A significant relationship between pain and sleep has been
noted (Marin et al., 2006), but few studies have compared bedding
systems or have attempted to obtain data for accurately recom-
mending mattresses for the improvement in sleep quality or
reduction in specific musculoskeletal discomfort. While some have
suggested that mattress differences do not significantly affect
sleep quality (Sullivan, 1993; Scharf et al., 1997; Buysse and
Reynolds, 1999), most researchers agree that sleep surfaces are
*Corresponding author. Tel.: þ1 405 744 6632; fax: þ1 405 744 7758.
E-mail address: Bert.jacobson@okstate.edu (B.H. Jacobson).
Contents lists available at ScienceDirect
Applied Ergonomics
journal homepage: www.elsevier.com/locate/apergo
0003-6870/$ esee front matter Ó2009 Published by Elsevier Ltd.
doi:10.1016/j.apergo.2010.05.004
Applied Ergonomics 42 (2010) 91e97
not alike and that some will provide better support and comfort
than others. For example, an early study found that 7% of sleep
problems were related to an uncomfortable mattress and that
comfort and support generated by the sleep surface was related to
sleep quality and efficiency (Addison et al., 1986). Others have
concluded that certain sleep surfaces result in low back and
shoulder discomfort (Akgun et al., 2004; Sigman and Richmond,
1995). One study found that subjects developed back pain after
sleeping on foam mattresses (Koul et al., 2000) while another
study suggested that there was no significant difference between
foam and innerspring mattresses in sleep stages, number of
wakes, or total sleep time (Scharf et al., 1997). Bergholdt et al.
(2008) evaluated patients with chronic low back pain using
three beds: 1) a water bed, 2) a foam mattress, and 3) a “hard”
mattress and found that their participants favored the water bed
and the foam mattress over the hard bed. In contrast a comparison
of beds described as “hard”,“softer”, water, and water/foam,
subjects with back pain reported reduced pain after sleeping on
“hard”beds (Garfin and Pye, 1981). No definition of the terms
“hard”or “soft”was included. In another study (Monsein et al.,
2000) involving patients with chronic back pain, sleep quality
and back pain were rated by visual analog scales after sleeping on:
a) subjects’personal bed, b) an adjustable air bed, and c) again on
their personal bed. The authors found that the air bed reduced
pain and increased the quality of sleep.
While much ambiguity exists among research seeking to
establish a sleeping surface for the benefit of reducing back and
shoulder pain and to increase sleep comfort, a much more consis-
tent case has been established for medium-firm sleep surfaces. In
one study Jacobson et al. (2002), found that medium-firm
mattresses reduced clinically diagnosed back pain as well as
shoulder pain and spine stiffness while positively affected sleep
quality. In other studies subjects with minor sleep disturbances
benefited significantly in sleep quality and efficiency with the
introduction of medium-firm bedding systems (Jacobson et al.,
2006, 2008). Furthermore, Kovacs et al. (2003) and Hadler and
Evans (2003) concluded that medium-firm mattresses reduce
low-back pain more so than firm mattresses. Health care practi-
tioners frequently see patients with complains of disturbed sleep,
shoulder pain, or back pain while in the bed and/or upon rising, but
little information exists for recommending a mattresses specificto
the ailment. Jacobson et al. (2002) commented on the fact that
mattresses are sold as one- type-fits-all, but recommended that
heavier individuals consider greater support in a mattress.
Since different sleeping position generate different surface
contact and pressure points it is possible that the three basic sleep
positions (supine, side, prone) require unique qualities in the
support and softness of mattress. Unsupported sleeping positions
places stress on the spine and back pain sufferers should identify
for themselves the positions that provide the most comfort. In
general, for those with back pain the two recommended sleeping
position are a) on the side with the knees drawn up (fetal position)
and b) on the back with a small pillow underneath the back of the
knees to maintain the natural curve of the lower back. Typically,
a person who suffers from pain will adopt sleeping positions that
minimize the pain (Tetley, 2000; Mayo Clinic, 2008, 2010).
While studies have focused on various surfaces in relation to
pressure sores, few have addressed mattresses in conjunction with
low back pain. Recent advancement in materials used in the
construction of mattresses has resulted in claims of greater comfort
and reduction in pressure gradients exerted by certain body areas
few studies have attempted to investigate mattress construction
based on sleeping positions. One study attempted to compare a flat
bed with a flat bed equipped with a specifically designed lumbar
body support on ratings of discomfort in patients with low back
pain and found that that the support significantly reduced low back
pain (Derman et al., 1995).
The purpose of this study was to assess the effectiveness of
individually prescribed medium-firm mattresses based on domi-
nant sleeping position on sleep quality and comfort in participants
diagnosed with low back pain and stiffness.
2. Methods
2.1. Participants
Subsequent to approval of the study by University Institutional
Review Board, regional chiropractic doctors were asked to refer
patients to the study who were diagnosed with lower-back pain for
three or more months. To be included in the study participants
were those without referred pain, but with presence of pain while
lying in bed or upon rising. Exclusion criteria were use of medica-
tions known to interfere with sleep, habitual prostration, possible
systemic disease, inflammatory disease, cancer, fibromyalgia, and
pregnancy (Kovacs et al., 2003). Of the original 43 referred patients,
27 met all criteria. Characteristics of the 27 participants included in
the study were: Females, n¼14; males, n¼13; age 44.8 yrs SD
14.6, weight 174 lb. SD 39.6, height 68.3 in. SD 3.7 (Table 1).
Personal interviews reaffirmed that none of the participants pre-
sented with back, neck, arthritic or circulatory issues; degenerative,
bulging or disc fusions; type two diabetes; fibromyalgia or rheu-
matoid arthritis; plates, rods or screws; or severe allergies. In
addition to demographic characteristics, visual observation as well
as height, weight, and BMI.
2.2. Procedure
Following referral by chiropractic physicians, prospective
participants were contacted and asked to complete a questionnaire
containing demographic characteristics, sleep related information
and items specific for inclusion in the study. The four items specific
to sleep were: On average, how many nights per week do you 1)
experience poor sleep quality, 2) wake up with shoulder pain, 3)
wake up with back pain, and 4) wake up with joint or muscle
stiffness? Participants recorded a number between 1 and 7 repre-
senting the number of days the condition was present during the
week. These data were again collected at the end of the study. Also,
participants were asked to provide a percentage of each position
(supine, prone, side) in which they slept. While it may be difficult
for the average individual to accurately determine their most
prominent sleeping position, typically, individuals living with pain
identify and adopt certain sleeping positions that are favored over
others in an attempt to reduce discomfort.
Participants were then given directions in how to use visual
analog scales (VASs) to assess the dependent variables (back pain,
back stiffness, quality of sleep, and comfort). With the side position
being a prominent sleeping position shoulder pain was shoulder
pain was included in the assessment.
Table 1
Participants’characteristics. N¼26.
Mean Min Max SD
Age 44.8 25.0 76.0 14.6
Height (cm) 173.5 149.8 190.5 9.4
Weight (kg) 74.1 45.4 128.4 20.3
Side sleep 58.8 15.0 100.0 28.1
Prone sleep 31.8 0.0 85.0 23.2
Supine sleep 8.4 0.0 40.0 11.2
Bed price ($) 1090 600 1700 302.0
B.H. Jacobson et al. / Applied Ergonomics 42 (2010) 91e9792
Visual Analog Scales contain 100 mm lines with polar extreme
labels. The VAS for back and shoulder pain contained discriminate
labels of “None”and “Extreme”. The back stiffness VAS contained
discriminates of “Extreme Stiffness”and “No Stiffness”and the
VASs for sleep quality and comfort contained opposites of “Excel-
lent”and “Very Poor”. To rate each variable, participants were
asked to place a perpendicular mark along the line that best rep-
resented their perception of pain/comfort. Visual analog scales
provide an accurate measure of subjective pain and have been used
extensively in similar studies (Marin et al., 2006; Jacobson et al.,
2002, 2006, 2008; Kovacs et al., 2003; McKay et al., 2003;
Gemmell et al., 2003).
As has been done previously (Garfin and Pye, 1981; Monsein
et al., 2000; Enck et al., 1999; Bader and Engdal, 2000; Jacobson
et al., 2002, 2006, 2008; McKay et al., 2003) and due to the
complex logistics and impracticality of an independent control
group design, the research format employed a single group, pre-
testeposttest design in which the subjects served as their own
controls. It has been suggested that the introduction of a “control”
bedding system is inappropriate in this type of study since the
introduction of a “control”bedding system essentially serves as an
additional experimental bedding system and not a standard of
measurement (Jacobson et al., 2002, 2006). The current research
design followed the protocol of previous studies (Bader and Engdal,
2000; Monsein et al., 2000; Jacobson et al., 2002, 2008) in which
comparisons between experimental beds and the subjects’
personal beds were made. In a previous study by Jacobson et al.
(2006) participants’beds averaged over nine years old and the
authors suggested that it may be presumptuous to assume older
beds provide the same support and comfort as newer beds.
Therefore, in the present study, a unique criterion for standardizing
personal beds was to only include participants who slept on beds
less than five years old.
For baseline data (pretest) subjects slept in their personal beds
for three consecutive weeks and rated Monday through Friday each
dependent variable on the VASs upon waking (Monsein et al., 2000;
Jacobson et al., 2002, 2006). Ratings were conducted by placing
a perpendicular mark through the VAS line that corresponded to
their perceptions of pain, stiffness, sleep quality and comfort.
Subjects rated the categories after sleeping in their personal beds
and were cautioned to avoid rating their sleep following heavy
alcohol consumption, trauma, or any extraordinary emotional or
physical event that could potentially interfere with sleep. If any
such non-typical changes occurred the subjects were told to rate
their sleep on a substitute day representing their typical lifestyle.
After completing the three-week baseline recordings, participants
contacted the researchers who arranged for the individually
prescribed mattresses to be delivered and installed at the partici-
pant’splace of residence. Beds were assigned based on the partic-
ipants’sleeping position and anthropometric frame. For example,
for those who predominantly slept on the side, mattresses were
designed to reduce the pressure exerted by the relatively small
shoulder and hip areas.
Mattress contained layers of hypo-allergenic, non-toxic visco-
polyurethane foam (memory foam) and latex combined with
a reverse-base, steel spring component situated exclusively for
selected sleeping positions and providing a medium-firm support.
The specific materials contained in the construction of the
mattresses were: velour cover; individually pocketed coil inner-
spring units; 360 degree foam encasement; fill materials eTalalay
latex and plant oil based visco-elastic polyurethane foam (memory
foam); quilting eECO foam. Visco-polyurethane foam is developed
from polyurethane plus added chemicals that increase viscosity
and density. High density visco-polyurethane foam has an open cell
structure that utilized the individual’s body temperature and
weight allowing it to mold itself to the shape of the body thus
spreading the individual’s body pressure over a greater area. Latex
mattress cores are perforated with holes. The size of the holes
determined the softness of the core. The latex mattress cores
contained sections with different sized holes regulating the soft-
ness in selected areas based on the participant’s sleeping position.
“Talalay”latex refers to the method in which the latex is formed. In
this process the rubber is agitated into foam and poured into a mold
and sealed in a vacuum. The mold is then flash-frozen to stabilize
the rubber and subsequently heated to assure evenness and
a consistent cell structure top to bottom and edge to edge. For the
current study, the foam and the latex layers were strategically
placed to provide either a softer or a firmer surface based on the
participant’s dominant sleeping position. For the current study one
mattress was constructed for side and back sleepers, but could be
used for supine sleepers if considered “petite”or with small
anthropometric characteristics. Construction of this mattress
utilized selected thicknesses and placement of Talalay Latex and
memory foam with the prominent pressure points considered. The
mattress was also designed to support individuals of size by
considering the density of the materials between the body and the
individual pocket coils. Another mattress was designed to accom-
modate back, side, and supine sleepers by considering that the
upper and lower trunk area requires support and stability. Again
the latex and foam were of selected density and layered according
to pressure points.
Simultaneously to the delivery of the prescribed bedding
system, subjects received new VASs and were asked to rate each
variable Monday through Friday for 12 continuous weeks.
Following the protocol of others (Bader and Engdal, 2000; Jacobson
et al., 2002, 2006) and in order to reduce external, confounding
factors and to provide normalcy to the sleep environment, subjects
slept in their own bedrooms with their personal linen and pillows.
Subjects also controlled their own thermal environment. After
completing the 12-week rating, subjects submitted their VASs and
sleep questionnaires for analysis.
2.3. Statistical analysis
Data were collected via VASs on five dependent variables (low
back pain, shoulder pain, back stiffness, sleep quality, and sleep
comfort) over a period of 15 weeks, generating 75 observations per
variable, per subject. Since the three-week pretest means were very
similar (Back pain ¼6.33 range, Shoulder pain ¼4.43 range,
Stiffness ¼2.38 range, Quality ¼5.52 range, and Comfort ¼2.37
range), the three pretest week means were averaged yielding one
three-week means to compare with posttest means. For the
Table 2
Means, standard errors, and confidence intervals for back pain by time. F(12, 180) ¼
8.4093, p<0.01.
Time Mean Std. err. CI 95.00% CI þ95.00%
Pretest 50.55 3.44 43.22 57.92
Post wk1 32.64 7.21 17.26 48.02
Post wk 2 25.85 4.41 16.44 35.26
Post wk 3 20.52 3.74 12.54 28.49
Post wk 4 18.74 3.94 10.33 27.16
Post wk 5 25.66 5.93 13.01 38.31
Post wk 6 21.55 5.26 10.32 32.77
Post wk 7 21.26 5.15 10.26 32.25
Post wk 8 18.37 4.68 8.39 28.35
Post wk 9 18.66 4.93 8.15 29.17
Post wk 10 16.81 4.46 7.29 26.32
Post wk 11 16.32 3.81 8.12 24.44
Post wk 12 17.87 3.84 9.60 26.06
B.H. Jacobson et al. / Applied Ergonomics 42 (2010) 91e97 93
posttests, each 12-week mean was calculated. Data were compared
using repeated measures ANOVA accompanied by NewmaneKeuls
post-hoc tests for those variables yielding significant Fvalues. For
the four items dealing with weekly sleep problems, Wilcoxon
Matched Pair analyses were used to compare pre- and posttests. An
alpha level of p<0.01 was considered significant.
3. Results
Following individual determination of mattresses based on
sleeping position and mattress delivery, one participant requested
a mattress replacement after a week of rating. After reassessment
and mattress replacement the participant was satisfied and
continued with the study. The averagecost of the participant’s beds
was approximately $1090 and the average bed age was 3.2 yrs. The
primary sleeping positions were: 58.8% side, 31.8% supine, and 8.4%
prone.
Means, standard errors, and confidence intervals are presented
in Tables 2e6. Analysis of the pre- and posttest means resulted in
significant differences in back pain (F¼8.49; p<0.01), back stiff-
ness (F¼22.93; p<0.01), shoulder pain (F¼9.15; p<0.01), sleep
quality (F¼13.94; p<0.01), and sleep comfort (F¼21.33; p<0.01)
(Tables 2e5). With the exception of back pain, NewmaneKeuls
post-hoc analyses yielded significant differences between pretest
means and for all 12-week posttests with no significant differences
within the 12-week period. For back pain, we found significant
differences between pretest and all 12-week posttest mean and
between the first posttest mean and weeks 4 and weeks 8e12 (Figs.
1e3), thus indicating progressive improvement in both back pain
and stiffness while sleeping on the new mattresses.
Some have suggested that new mattresses require a break-in
period before delivering full sleep comfort (Bader and Engdal,
2000). In the current study, we saw no significant negative
changes between the first few posttest weeks and the week at the
end of the study, suggesting that the change was sustainable.
Analysis of the pretest mean and the 12th week posttest means
yielded the following proportional improvement: lower back
pain ¼64.6%, back stiffness ¼66.2%, shoulder pain ¼60.1%, sleep
quality ¼51.0%, and sleep comfort ¼54.8%.
Results of the Wilcoxon Matched Pairs analyses of the pre- and
posttest data regarding average number of days of discomfort per
week are presented in Table 7 and Fig. 4. Results yielded significant
reduction in the number of nights participants experienced poor
sleep quality (Z¼3.61; p<0.01; 5.47d vs. 1.47d), shoulder pain
(Z¼3.52; p<0.01; 4.11d vs. 1.05d), back pain (Z¼3.73; p<0.01;
5.16d vs. 1.53d), and joint/muscle stiffness (Z¼2.68; p<0.01; 5.12d
vs. 2.21d).
4. Discussion
The current bed market provides a wide variety of sleep
surfaces. Beyond the traditional and most common coil spring
mattresses, newer materials such as latex and memory foam is used
in the construction of mattresses in order to provide greater
support and comfort. The density, thickness and order of layering is
considered important in considering support and comfort because
the construction and design is thought to redistribute the body
Table 5
Means, standard errors, and confidence intervals for sleep quality by time. F(12,
180)¼13.947, p<¼0.01.
Time Mean Std. err. CI 95.00% CI þ95.00%
Pretest 38.20 2.94 31.91 44.48
Post wk1 68.45 5.25 57.24 79.66
Post wk 2 70.605 5.20 59.51 81.69
Post wk 3 73.48 5.13 62.54 84.40
Post wk 4 74.44 4.99 63.85 85.12
Post wk 5 71.12 5.71 58.92 83.33
Post wk 6 75.18 4.92 64.63 85.62
Post wk 7 76.67 4.48 67.11 86.24
Post wk 8 74.73 4.82 64.41 85.12
Post wk 9 76.76 4.96 66.16 87.36
Post wk 10 78.16 4.83 67.70 88.56
Post wk 11 78.62 4.38 69.39 87.94
Post wk 12 77.95 4.64 67.93 87.92
Table 6
Means, standard errors, and confidence intervals for sleep comfort by time. F(12,
180)¼21.337, p¼0.01.
Time Mean Std. err. CI 95.00% CI þ95.00%
Pretest 36.02 3.17 29.25 42.78
Post wk1 70.98 5.61 59.03 82.94
Post wk 2 75.41 4.61 65.58 85.25
Post wk 3 78.24 4.25 69.18 87.31
Post wk 4 78.60 4.05 69.95 87.25
Post wk 5 80.12 3.62 72.38 87.86
Post wk 6 80.00 3.85 71.77 88.22
Post wk 7 79.35 4.29 70.20 88.50
Post wk 8 79.33 4.80 69.09 89.57
Post wk 9 78.16 5.14 67.19 89.13
Post wk 10 79.20 5.09 68.34 90.07
Post wk 11 79.95 4.61 70.11 89.80
Post wk 12 79.75 4.31 70.54 88.95
Table 4
Means, standard errors, and confidence intervals for shoulder pain by time. F(12,
168) ¼9.1501, p<0¼0.01.
Time Mean Std. err. CI 95.00% CI þ95.00%
Pre-test 47.73 6.59 33.58 61.87
Post wk1 18.37 4.34 9.06 27.69
Post wk 2 15.51 3.65 7.68 23.34
Post wk 3 14.24 3.87 5.92 22.56
Post wk 4 14.33 4.03 5.67 22.99
Post wk 5 16.77 4.90 6.25 27.29
Post wk 6 17.40 4.90 6.89 27.91
Post wk 7 15.46 4.14 6.57 24.35
Post wk 8 16.38 4.51 6.70 26.07
Post wk 9 18.06 4.98 7.36 28.76
Post wk 10 20.35 6.57 6.25 34.45
Post wk 11 17.76 5.67 5.58 29.94
Post wk 12 18.31 5.43 6.66 29.95
Table 3
Means, standard errors, and confidence intervals for back stiffness by time. F(12,
180)¼12.617, p<0.01.
Time Mean Std. err. CI 95.00% CI þ95.00%
Pretest 58.22 4.33 48.99 67.45
Post wk1 28.27 5.84 15.81 40.72
Post wk 2 23.56 4.87 13.17 33.94
Post wk 3 22.83 4.75 12.70 32.96
Post wk 4 20.14 4.46 10.62 29.66
Post wk 5 20.87 5.05 10.09 31.65
Post wk 6 21.35 5.10 10.47 32.23
Post wk 7 19.16 4.81 8.90 29.43
Post wk 8 19.37 4.97 8.76 29.98
Post wk 9 18.62 4.59 8.82 28.42
Post wk 10 21.66 5.25 10.47 32.86
Post wk 11 19.39 5.17 8.36 30.42
Post wk 12 19.56 4.58 9.79 29.32
B.H. Jacobson et al. / Applied Ergonomics 42 (2010) 91e9794
weight and to reduce pressure that may cause muscle and joint
discomfort. In the current study, medium-firm sleeping surfaces
constructed with layers of visco-polyurethane foam, latex and
pocked coils were prescribed for participants based on their
dominant sleeping position, weight and musculoskeletal ailment.
Studies have concluded that the sleep surface can contribute to
discomfort and that sleeping on certain sleep surfaces may be more
beneficial than others (Akgun et al., 2004; Koul et al., 2000). Indeed,
it has been concluded that for those suffering from chronic low
back pain and sleep problems, quality of the mattress is relative to
the sleep quality (Lahad and Sarig-Bahat, 2007).
Previous studies have concluded that medium-firm sleep
surfaces may be the most beneficial for those with chronic low back
pain (Jacobson et al., 2002, 2006; Kovacs et al., 2003; Hadler and
Evans, 2003). For instance, Jacobson and associates in two sepa-
rate studies (Jacobson et al., 2002) concluded that medium-firm
mattresses reduced clinically diagnosed back pain, and positively
affected sleep quality and that subjects’with minor, non-clinical
sleep disturbances also benefited from sleeping on medium-firm
mattresses (Jacobson et al., 2002). Others have also concluded that,
medium-firm mattresses can reduce low-back pain more so than
firm mattresses (Hadler and Evans, 2003) and that medium-firm
mattress may be more beneficial than a firm mattress in matters of
back pain, pain on rising, and daytime back pain (Kovacs et al.,
2003). Consistent with these suggestions, Israeli guidelines for
prevention of low back pain, based on recommendations of the
Europiena Commisitono, COSST Action B13 states that persisting
low back pain symptoms may be reduced with a medium efirm
rather than a hard mattress (Lahad and Sarig-Bahat, 2007). The
uniqueness of the present study was the attempt to individually
prescribe mattresses based on sleeping positions and the utilization
of both visco-elastic polyurethane foam and Talalay latex to
distribute pressure over a greater surface area generated by the
prominent sleeping position. Most previous studies have utilized
coil spring mattresses.
It has been suggested (Bader and Engdal, 2000) that a “pseudo-
placebo effect”may be responsible for initial high comfort ratings,
however, such perception eventually wear off with time. These data
indicate that the benefits derived from the new mattresses were
immediate and continued over a 12-week period. Furthermore, the
robust improvements stemming from the questionnaire given prior
to the onset of the study and again at the end of 12 weeks provide
further evidence of sustainability.
Bader and Engdal (2000) suggested that new mattresses require
a certain amount of break-in time to deliver full benefits. In the
present study, significant reductions in pain and stiffness and
increases in sleep quality and comfort were realized in the first
week and were sustained over the duration of the study. It is
plausible that the newer materials used in the mattress construc-
tion requires no actual break-in time.
Similarly to the pseudo-placebo effect it may be argued that the
participants preferred the experimental mattresses because they
were new and provided at no cost, thus generating an obligatory
response akin to a Rosenthal effect. Jacobson et al. (2008)
acknowledged that new beds provided at no cost may influence
participants to overrate the benefits of the bed. They suggest that
such a phenomenon is minimized when subjects are not given any
information about the expected outcome of the study and any
perceived obligation would subside over time. Additionally, for the
present study, all pretest data was submitted to the researchers
prior to rating the new mattresses, making it impossible for the
participants to compare pretest with posttest data.
The possibility of a Hawthorn effect may also threaten research
results. A related study used the common definition of the Haw-
thorne effect as the suggestion that people will respond to any
novel change, not because of any specific condition being tested,
Fig. 3. Pre- and post12-week means for sleep quality and comfort.
Table 7
Wilcoxon matched pair analysis for pre- and posttest means by weekly sleep items.
Items Mean SE tdf
Poor sleep quality
Pretest 5.47 1.80 7.48* 18
Posttest 1.47 1.80
Shoulder pain
Pretest 4.10 2.23 5.61* 18
Posttest 1.05 1.80
Back pain
Pretest 5.15 1.80 8.64* 18
Posttest 1.52 1.64
Back stiffness
Pretest 5.10 2.18 3.88* 18
Posttest 2.21 2.12
*p<0.01.
Fig. 1. Pre- and 12-week post means for back pain and stiffness.
Fig. 2. Pre- and 12-week post means for shoulder pain.
B.H. Jacobson et al. / Applied Ergonomics 42 (2010) 91e97 95
but because of the attention they receive (Jacobson et al., 2008).
Similarly to previous studies (Jacobson et al., 2002, 2006, 2008)
participants were not personally monitored over the 12-week
experimental period except for follow-up calls to assure compli-
ance in filling out the daily VASs.
5. Conclusion
Conclusions following previous research (Jacobson et al., 2002,
2008) have centered on the dearth of knowledge regarding sleep
surfaces and the need to continue to compare and assess
mattresses. Of particular interest and importance is the distinct
possibility that a properly fitted mattress can reduce common
musculoskeletal pain and improve sleep quality and comfort. The
current study supports the growing evidence that medium-firm
mattresses are suitable in providing sleep quality and comfort.
These data provide impetus for continued research in determining
the effectiveness of specifically constructed sleep surfaces based on
sleeping positions in order to enhance sleep quality and to reduce
musculoskeletal pain. In the current study the participants expe-
rienced considerable improvement in quality sleep (73%), shoulder
pain (75%), back pain (70%), and joint/muscle stiffness (57%)
following 12-weeks of sleeping on the new mattresses.
A previous study suggested that the average age of their
participants’beds (9.5 yrs) may have contributed to a slow
progression of poor sleep and musculoskeletal discomfort due to
a deterioration of support provided by the beds over the years
(Jacobson et al., 2002). To reduce the possibility of replacing a very
old bed, the current study controlled for the age of the participants’
beds by only including those with beds five years or younger in
order to reduce any confounding variables attributed to bed age.
Longevity and durability of mattresses are difficult to determine,
but the Better Sleep Council (2009) suggest that the ‘life’of
a mattress depends on original quality, usage and recommend that
the sleep surface be evaluated after five to seven years. Newer
materials such as latex and visco-elastic polyurethane foam are
resilient and durable, but changes in anthropometrics, chronic pain,
and aging may also require a change in the bedding system.
Jacobson et al. (2002) concluded that new mattresses can signifi-
cantly improve sleep and that sleep quality may be dependent on
timely replacement of mattresses.
An inherent and unresolved issue centers around terms such as
“firm”and “soft”which are not globally defined either in the
market place or in research. Yet, these data support both the benefit
of a “medium-firm”sleep surface constructed of layers of visco-
elastic polyurethane foam and latex and the suitability of
prescribing the sleep surface based on the prominent sleeping
position.
Support
Bob Mills Furniture.
References
Addison, R.G., Thorpy, M.J., Roth, T., 1986. A survey of the United States public
concerning the quality of sleep. Sleep Res. 16, 244.
Akgun, K., Birtane, M., Akarirmak, U., 2004. Is local subacromial corticosteroid
injection beneficial in subacromial impingement syndrome? J. Clin. Rheumatol.
23, 496e500.
Bader, G.G., Engdal, S., 2000. The influence of bed firmness on sleep quality. Appl.
Ergon. 31, 487e497.
Better Sleep Council. 2009. http://www.bettersleep.org/pdfs/BetterSleepGuide_
English.pdf.
Bergholdt, K., Fabricius, R.N., Bendix, T., 2008. Better backs by better beds. Spine 33,
703e708.
Buysse, D.J., Reynolds III, C.F., 1999. In: Thorpy, M.J. (Ed.), Handbook of Sleep
Disorders and Insomnia. Dekker Inc, New York, pp. 375e433.
Chilcott, L.A., Shapiro, C.M., 1996. The socioeconomic impact of insomnia. An
overview. Pharmacoeconomics 10 (Suppl. 1), 1e14.
Derman, K., Derman, E., Noakes, T., 1995. A lumbar body support (KBS 2000) alters
lumbar muscle recruitment patterns in patients with acute-upon-chronic lower
back pain. S. Afr. Med. J. 854, 278e282.
Drake, C., Richardson, G., Roehrs, T., Schofield, H., Roth, T., 2004. Vulnerability to
stress-related sleep disturbance and hyperarousal. Sleep 27, 285e291.
Enck, P., Walten, T., Traue, H.C., 1999. Association between back pain, quality of
sleep and quality of mattresses. Double-blind pilot study with hotels guests.
Schmerz 11, 205e207 (in German).
Gemmell, H.A., Jacobson, B.H., Hayes, B.M., 2003. Effect of a topical herbal cream on
osteoarthritis of the hand and knee: a pilot study. JMPT 26, 315e323.
Garfin, S.R., Pye, S.A., 1981. Bed design and its effect on chronic low back pain e
a limited controlled trial. Pain 10, 87e91.
Godet-Cayre’, V., Pelletier-Fleury, N., Le Valliant, M., et al., 2006. Insomnia and
absenteeism at work. Who pays the cost? Sleep 1, 179e184.
Hadler, N.M., Evans, A.T., 2003. Medium-firm mattresses reduced pain-related
disability more than firm mattress in chronic, nonspecific low-back pain. ACP J.
Club 141, 3.
Hillman, D.R., Murphy, A.S., Pezzullo, L., 2006. The economic cost of sleep disorders.
Sleep 29, 299e305.
Jacobson, B.H., Gemmell, H.A., Hayes, B.M., et al., 2002. Effectiveness on selected
bedding system on quality of sleep, low back pain, shoulder pain, and spine
stiffness. JMPT 25, 88e92.
Jacobson, Bert H., Wallace, Tia, Gemmell, H., 2006. Subjective rating of perceived
back pain, stiffness and sleep quality following introduction of medium-firm
bedding systems. J. Chiropr. Med. 5, 128e134.
Jacobson, B.H., Wallace, T.J., Smith, D.B., Kolb, T., 2008. Grouped comparisons of
sleep quality for new and personal bedding systems. Appl. Ergon. 39, 247e254.
Koul, P.A., Bhat, M.H., Lone, A.A., Koul, A.N., et al., 2000. The foam mattress-back
syndrome. J. Assoc. Physicians India 48, 901e902.
Fig. 4. Pre- and posttest means for number of nights per week by complaint.
B.H. Jacobson et al. / Applied Ergonomics 42 (2010) 91e9796
Kovacs, F.M., Abraira, V., Pena, A., et al., 2003. Effect of firmness of mattress on
chronic non-specific low-back pain: randomized, double-blind, controlled,
multicentre trial. Lancet 15, 1599e1604.
Lahad, A., Sarig-Bahat, H., 2007. Israeli guidelines for prevention of low back pain.
Harefuah 146, 253e257. 320.
Lahm, R., Iaizzo, P.A., 2002. Physiologic responses during rest on a sleep system at
varied degrees of firmness in a normal population. Ergonomics 45, 798e915.
Lee, K.A., 2005. Critical components of sleep assessment for clinical practice
settings. Issues Ment. Health Nurs. 26, 712e739.
Levy, H., Hutton, W.C., 2000. Mattresses and sleep for patients with low back pain:
a survey of orthopaedic surgeons. J. South. Orthop. Assoc. 20, 185e187.
Marin, R., Cyhan, T., Miklos, W., 2006. Sleep disturbance in patients with chronic
back pain. Am. J. Phys. Med. Rehabil. 85, 430e435.
Mayo Clinic, 2008. Are there sleep positions that can help reduce back pain? Mayo
Clinic Women’s Healthsource 12 (6), 8.
Mayo Clinic.com. 2010. http://www.mayoclinic.com/health/sleeping-positions/
LB00003_D.
McKay, L., Gemmell, H.A., Jacobson, B.H., 2003. Effect of a topical herbal cream on
the pain and stiffness of osteoarthritis: a randomized double-blind, placebo-
controlled clinical trial. J. Clin. Rheumatol. 9, 164e169.
Monsein, M., Corbin, T.P., Culliton, P.D., Merz, D., et al., 2000. Short-term outcomes
of chronic back pain patients on an airbed vs innerspring mattresses. MedG-
enMed 11, E36.
National Sleep Foundation, 2005. Sleep in America poll. Summary of the Sleep in
America poll. Available from: www.sleepfoundation.org/ [Online] [Cited 2006
May 1].
Ohanyon, M.M., Lemoinie, P., 2004. Sleep and insomnia markers in the general
population. Encephale 30, 134e140.
Reiter, J., 2005. Deciphering the complexities of diagnosing and treating insomnia.
Psychiatr. Times 22, 74e76.
Scharf, M.B., Stover, R., McDannold, M., et al., 1997. Comparative effects of sleep on
a standard mattress to an experimental foam surface on sleep architecture and
CAP rates. Sleep 20, 1197e1200 .
Sigman, S., Richmond, J., 1995. Office diagnosis of shoulder disorder. Physician
Sports Med. 23, 25e31.
Sullivan, J., 1993. Beds. In: Carskadon, M. (Ed.), Encyclopedia of Sleep and Dreaming.
Macmillan, New York, pp. 66e68.
Tetley, M., 2000. Instinctive sleeping and resting postures: an anthropological and
zoological approach to treatment of low back and joint pain. BMJ 321 (7276),
1616e1618 .
B.H. Jacobson et al. / Applied Ergonomics 42 (2010) 91e97 97
