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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Initial Experiences with Longitudinal Self-Tracking of Sleep and Low Back Pain</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Andy Alorwu</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Aku Visuri</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Simo Hosio</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Center for Ubiquitous Computing, University of Oulu</institution>
          ,
          <addr-line>Pentti Kaiteran katu 1, 90570 Oulu</addr-line>
          ,
          <country country="FI">Finland</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Low Back Pain (LBP) is a leading cause of disability globally, making it a serious public health concern. In this paper we present the initial results and analysis of a longitudinal self-tracking study on sleep and LBP using a custom built mobile application. We designed and deployed a mobile app for a period of 7 months to collect daily and monthly sleep and low back pain data using custom and standardized questionnaires. We discuss the feasibility of our approach for longitudinal data collection. Our data analysis reveals heterogeneity in user perceptions of factors that afect their sleep and LBP. Combining our quantitative and qualitative analyses, we contribute to literature on sleep and LBP.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Low Back Pain (LBP)</kwd>
        <kwd>Sleep</kwd>
        <kwd>Longitudinal study</kwd>
        <kwd>Self-tracking</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <sec id="sec-1-1">
        <title>We present an exploratory study where we used a</title>
        <p>
          custom-built mobile application “Sleep Better with Back
The global population of people aged 60 and above has Pain” to investigate if, and in what ways, the felt pain
been growing steadily. Aided by advances in technology, afects the quality of sleep among people living with LBP.
healthcare delivery and the medical field, the average life Our main contributions are:
expectancy seems to be increasing. The longer people
live, the more susceptible they become to conditions such 1. A contribution to the literature on sleep and LBP,
as Low Back Pain (LBP) [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ]. Thus, LBP has become a by investigating the relationship between LBP
central concern in the public health domain [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ]. The and sleep.
economic efect of LBP on individuals, families, and the 2. An initial prototype of a mobile application to
society at large is high, with societal costs estimated to collect massive amount of subjective data on sleep
be 1% to 2% of the gross national product in Western and LBP.
countries, with a vast majority of these costs caused by 3. A feasibility study that highlights important
condisability and loss of work productivity [
          <xref ref-type="bibr" rid="ref3 ref4 ref5">3, 4, 5</xref>
          ]. textual aspects that must be considered in future
        </p>
        <p>
          Sleep is a vital biological function essential for the deployments.
overall health of mammalian organisms [6] and allows 4. We discuss how factors such as sleep time, wake
for psychological recuperation and memory consolida- up time, sleep disruptions, and pain intensity at
tion [
          <xref ref-type="bibr" rid="ref5">5, 7</xref>
          ]. In the same vein, poor sleep poses a potent night impact the felt restfulness of participants.
risk factor for a number of physical and psychological ail- 5. Factors leading to poor sleep among people living
ments including obesity, dementia, diabetes, and chronic with LBP is heterogeneous and not only due to
pain [
          <xref ref-type="bibr" rid="ref5">8, 9, 5, 10</xref>
          ]. Poor sleep quality is common among pain.
people sufering from chronic or acute pain such as LBP
[
          <xref ref-type="bibr" rid="ref5">5</xref>
          ]. The results from our study are also encouraging
con
        </p>
        <p>We conducted a long term study that ofered daily cerning the number of completed daily surveys about
observations from the perspectives of people living with sleep and LBP for several months, which is promising
LBP to investigate the efects of LBP on sleep: how does considering our future deployment of the next version
back pain afect one’s sleep quality? In this vein, we also of the application.
consider how factors such as time of sleep, wake up time,
and sleep interruptions among others afect the perceived 2. Related Work
sleep quality and/or felt pain intensity of people living
with LBP.</p>
        <sec id="sec-1-1-1">
          <title>2.1. Low Back Pain</title>
          <p>
            Low Back Pain (LBP) adversely afects the quality of life
of people [11] and produces annual global costs
exceeding $100 billion [12]. Although there are numerous pain
conditions, back pain carries the greatest societal burden,
afecting nearly every adult at least once in their lifetime
[12]. The Global Burden of Disease (GBD) study esti- 3.1. On-boarding and Daily Use
mated that among 306 conditions, LBP ranked highest as
the most significant condition with respect to the number
of years lived with disability [
            <xref ref-type="bibr" rid="ref1">13, 1</xref>
            ].
          </p>
        </sec>
      </sec>
      <sec id="sec-1-2">
        <title>The setup of the app was designed to be simple for the</title>
        <p>
          users. It has a welcome screen (Fig. 1a) that on-boards
users by asking preliminary questions about user
demographics and past experience with pain. This welcome
2.2. Sleep screen also displays a consent checkbox which the user
Recent studies have reported that sleep dificulties such must agree to in order to proceed. A consent statement
as initiating and maintaining sleep, as well as experienc- is provided beside the checkbox and contains links to
ing inadequate sleep, can afect 20-30% of the western the “user agreement” and “privacy policy” screens.
Afpopulation on a daily to weekly basis [
          <xref ref-type="bibr" rid="ref5">5, 14</xref>
          ]. Sleep loss ter a successful on-boarding, the home screen (Fig. 1b)
has been reported to impair cognition, psychomotor func- that displays daily surveys to be taken by the user is
pretion, decision making, and immune function [15]. Poor sented. Clicking on a list item opens up a detailed view
sleep quality has also been considered to be a significant with a list of survey questions (Fig. 1d). After successfully
risk factor for people sufering with diseases such as dia- answering and submitting the answers to a survey, the
betes, dementia, depression, obesity, pain, among others completed survey is removed from the list depending on
[16, 9]. The physical and psychological changes associ- whether it is a daily or monthly survey. Monthly surveys
ated with poor sleep can significantly afect the quality are removed from the list for the given month once
anof life and overall well-being of people [17]. Inadequate swered. Daily surveys on the other hand are removed for
sleep also negatively impacts productivity and leads to the given day only, and are displayed again the next day.
substantial financial and non-financial costs, ultimately The app also has a settings screen (Fig. 1c) that enables
becoming an important social and economic burden [18]. the user to customize the application. Most importantly is
the notification time for the delivery of daily reminders to
answer a survey. Users receive daily push notifications at
2.3. The Relation Between Sleep and Pain the selected time to remind them to take the daily survey.
A set of two emojis (one happy face and one sad face) are
displayed one at a time on the home screen indicating a
completed survey (happy face) or a missing daily survey
(sad face).
        </p>
        <p>The “Sleep Better with Back Pain” app includes three
in-app questionnaires: daily survey, sleep survey, and
quality of life survey. The “daily” survey is taken daily
while the “sleep survey” and “quality of life survey” are
taken monthly.</p>
        <p>
          The exact mechanisms underpinning the sleep and pain
relationship are unclear but likely to involve multiple
contributors [19], such as depression [20], and daytime
napping [21]. The comorbidities between chronic pain and
sleep impairments have been shown in various studies
[
          <xref ref-type="bibr" rid="ref5">5, 22</xref>
          ]. Similarly, studies suggest that the management
of sleep may consequently improve co-morbid diseases
[23, 24]. The interaction between sleep and pain is
complex and challenging to understand [25]. A study by
Mathias et al. [19] established that adult patients with
chronic pain had worse measures for sleep onset latency
and eficiency, recurrent awakenings, and time awake
after sleep onset and exhibited worse scores on sleep
measures such as total sleep time and light sleep duration,
among others.
3.1.1. Daily Survey
        </p>
      </sec>
      <sec id="sec-1-3">
        <title>The daily survey comprised of the following items:</title>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>3. The “Sleep Better with Back</title>
    </sec>
    <sec id="sec-3">
      <title>Pain” app</title>
      <p>We designed a cross-platform mobile application to
collect periodical questionnaire data. The application was
built with Flutter1 and runs on both Android and iOS
mobile operating systems. Flutter is a cross-platform mobile
application development framework that makes it easy
to build apps for the Android and iOS mobile operating
systems using the same code base.
• Sleep time and wake up time, 5-point Likert-style
item: 1 (Earlier than normal) - 5 (Later than
normal)
• Time to fall asleep, 5-point item: 1 (Less time than</p>
      <p>normal) - 5 (More time than normal)
• Number of times waking up at night, 5-point item:</p>
      <p>1 (Less than normal) - 5 (More than normal)
• How rested you feel after waking up, 5-point item:
1 (Less rest than normal) - 5 (More rest than
normal)
• Severity of LBP pain, 1-point item: 0 (No pain)</p>
      <p>10 (Worst imaginable pain)
• How pain afected sleep and/or how sleep afected
pain: Free-form text
(a) On-boarding
(b) Home screen
(c) Settings screen
(d) Daily survey
(e) Sleep survey
(f) Quality of life
3.1.2. Monthly Questionnaires sleep duration, sleep eficiency, sleep disturbances, sleep
medication, and daytime dysfunction.</p>
      <p>The monthly sleep questionnaire is a standardized Pitts- The quality of life survey is a Patient-Reported
Outburgh Sleep Quality Index (PSQI) questionnaire devel- comes Measurement Information System (PROMIS-10)
oped by Buysee et al. [26] as a self-report on subjective standardized questionnaire comprising of 10 global items
sleep quality over a period of four weeks. It consists of that each represent a domain of health [27]. Global
phys19 items from which seven component scores that re- ical and mental health component scores are computed
veal the severity of various sleep problems are formed. from the global items. Results from PROMIS-10 can be
These components include: sleep quality, sleep latency,
used to assess patients’ perceptions of their health. The
physical health component scale comprises of four items
on: physical health, physical functioning, pain intensity,
and fatigue. The mental health component scale includes
items on: quality of life, mental health, satisfaction with
social activities and relationships, and emotional
problems. Two of the global items (general health and social
roles) are not used in the calculation of the physical and
mental component scores.</p>
      <p>A total of 35 people participated in our field study.
Participants were mainly recruited from our local campus
through our campus-wide email lists. However, we got
additional participants via Google’s Play Store as the app
was published publicly there. Participant ages ranged
between 20-68 (M = 38.03, SD = 12.94) with 20 females
and 15 males. Participants had diverse academic
qualiifcations and employment statuses. 20 hold a Master’s
degree or higher, 8 hold a Bachelor’s degree, 2 hold a
3.1.3. Reminder Notifications Vocational degree, and 3 hold a High School diploma
Notifications are delivered from our custom-built back- while 3 did not disclose their educational information.
end application through OneSignal 2 APIs. Data from the Concerning employment, 21 participants identified as
answered surveys are saved in an online Google Sheets having a full-time job, 7 have a part-time job while 3 are
document. User data is saved in a database hosted on our unemployed, 2 are retired, and 2 did not disclose their
own servers. The “Sleep Better with Back Pain” mobile employment status. None of the participants have had
app is hosted on Google Play. their back surgically operated by a doctor and the
number of years lived with LBP ranged from 0-38 (M = 9, SD
3.2. Pilot Experiment = 9.48). 20 participants have been clinically diagnosed
with LBP, 8 have chronic sciatica, 5 non-chronic sciatica,
Before embarking on the longitudinal deployment, we and 20 have no sciatica.
validated the feasibility of the app by conducting usabil- We also inquired about how active participants’
ity tests with four users within our research premises. lifestyle was using a single 0-10 item (0 - not at all
acDuring this session, we discovered some usability issues: tive to 10 - extremely active). The mean value was 5.51
1) mandatory questions were not marked with an asterisk (SD = 1.93). For inquiries about treatments and
self(*), 2) after completing a survey, the user is automatically management techniques used in managing their pain,
directed to the main screen without any message to indi- participants shared a variety of actions they take. Some
cate the survey was complete, and 3) the choice of font of these include: “exercises”, “yoga”, “massages”,
“stretchtype and color made visualization dificult. We also no- ing”, and “taking medication”. A more nuanced analysis
ticed technical issues such as 1) users finding it dificult of these is outside the scope of this article.
to select 0 on the 0-10 slider scale, and 2) the keyboard
not disappearing after users have finished typing an
answer. These insights were useful in improving the app 5. Results
design and functionality before embarking on the longer
deployment.</p>
    </sec>
    <sec id="sec-4">
      <title>4. DATA COLLECTION</title>
      <p>After making modifications to the app based on feedback
from the usability testing session, we launched the app
on the Google Play Store and published the study to
our campus wide email lists. We did not specify any
reward for participating in the study as we wanted to
reach people who really wanted to use the app or were
not motivated by any form of reward but were interested
in understanding their sleep and LBP. We also reached
out and recommended the study to previous participants
of studies conducted by co-authors. The study run for a
period of seven (7) months, from May to November 2021.</p>
      <sec id="sec-4-1">
        <title>2https://onesignal.com</title>
        <p>In the following sections, we present our quantitative
and qualitative findings, focusing primarily on the efect
of low back pain on the quality of sleep experienced by
people living with LBP.</p>
        <sec id="sec-4-1-1">
          <title>5.1. Quantitative Analysis</title>
          <p>5.1.1. Relationship between sleep quality and pain
intensity
We analysed the daily surveys (N = 1030) and computed
Spearman’s rank correlation to assess the relationship
between the collected variables and “well-restedness”. We
noticed a negligible negative correlation between pain
intensity and well-restedness (r(1028) = -.12, p &lt; .005)
and a negligible correlation between wake up time and
well-restedness ( r(1028) = .08, p = .01). Thus, the felt
pain was not strongly associated with how well-rested
participants felt the next morning. We also discovered a
weak negative correlation between sleep time and
wellrestedness (r(1028) = -.22, p &lt; .005). However, there was a
strong negative correlation between sleep disruption and
well-restedness (r(1028) = -.41, p = &lt; .005). Thus, and as
can be expected, sleep disruptions are associated with
how well-rested people feel in the morning. While these
ifndings are not surprising, they are indicative of the
app’s feasibility in overall data collection.
5.1.2. PSQI
The global PSQI score from the responses (N = 36) of our
study, which is the sum of all seven component scores
has a range of 0-21 points with actual scores ranging
from 4-16, an overall group mean of 8.4 (SD = 2.83,  =
.68). For the individual components, each with a possible
range of 0-3, the ranges were 0-3 except sleep disturbance
which had a range of 0-2. For each component, as well
as the global PSQI score, higher scores are an indication
of worse sleep quality.</p>
          <p>In Table 1, we examine the correlation of the PSQI
components in our cohort using Spearman rank
correlation. We found strong correlations between sleep quality
and use of sleep medication (r = .48, p &lt; 0.005), sleep
eficiency and sleep duration (r = .61, p &lt; 0.005), a moderate
correlation between sleep quality and sleep duration (r =
.36, p &lt; 0.05), sleep disturbance and daytime dysfunction
(r = .34, p &lt; 0.05). Sleep quality had little to no efect on
daytime dysfunction (r = -.06, p = 0.71) however.
5.1.3. PROMIS-10</p>
        </sec>
      </sec>
      <sec id="sec-4-2">
        <title>We show the multivariate correlation matrix of the</title>
        <p>PROMIS-10 domains of the results (N = 36) of our study
in Table 2. The mean physical health score of participants
was 13.67 (SD = 3.01) and the physical health T-score of
participants was lower (mean = 44.63, SD = 8.43) relative
to the standardized mean T-score of 50. Similarly, the
mean mental health score was 11.92 (SD = 3.23) and the
mental health T-score of participants was lower (mean
= 43.33, SD = 8.24) relative to the standard score. Thus
our participants have significantly lower physical and
mental function compared to the general population.</p>
        <sec id="sec-4-2-1">
          <title>5.2. Qualitative Analysis</title>
          <p>We analyzed 1030 responses to the open-ended daily
questionnaire item (i.e. users’ own elaboration on how
pain afected sleep or how sleep afected pain) following
a deductive thematic analysis process [28]. In using this
analytical method, the first author first coded the most
informative responses, generating the coding scheme
which was then shared with the other co-authors. The
authors held online meetings to discuss and resolve
disagreements with the coding. They further identified
aspects of the responses that would be most interesting to
present and discuss. In subsequent sections, we present
a subset of the findings from the analysis that we believe
best fits the scope of this article.
5.2.1. Pain before, during, and after sleep
Participants expressed various degrees of pain felt prior
to going to sleep, during sleep hours, and when they
woke up in the morning. While there were reported
feelings of pain prior to going to bed on some days, pain
before bed did not always result to a painful sleep. One
participant notes it was “...dificult to fall asleep due to the
pain but once I did, it didn’t bother my sleep” (Female, 42).</p>
          <p>In a similar vein, another participant exclaimed, “...it was
worst when going to bed, it did not bother me during the
night”(Male, 30).</p>
          <p>On the contrary, some participants were quick to
highlight the efect their LBP had on their sleep such as forcing
them to stay awake at night for hours. One participant
notes, “I stayed up two hours at night because of pain in
my hip” (Male, 49) and “I couldn’t rest well due to pain at
my back” (Male, 30). There were days however where
participants simply reported their LBP not having an
effect on their sleep despite the presence of the pain. One
participant stating that the “...pain did not disturb my
sleep” (Female, 48).</p>
          <p>It is also worth highlighting that good quality sleep
positively afected participants’ perception of pain in the
morning, “...sleeping helped pain” (Female, 48). This was
further supported by another who acknowledges to be 5.2.3. Exercises and active lifestyle
“t.h..ainn ausbuitalle”s(sFpeaminalteh, i6s7m)ionrdniicnagtibnegcaaupseotIesnletpiatlalybpitobsiettitveer Some participants highlight being engaged in an active
efect sleep can have on one’s LBP. lifestyle and sports. To this, we noticed a report of an</p>
          <p>While we see several instances of sleep aefcting pain increase in pain or sleeplessness due to pain after an
positively and pain having a negative efect on partici- intense or strenuous workout, “In the morning I felt some
pants’ sleep, we also report that there were days where lower back pain and stifness. It could be result from gym
participants were confident that neither sleep nor pain exercise” (Male, 38). Interestingly, sufering from LBP
had an efect on the other. One participant sums it all did not stop participants from indulging in an active
up, “I didn’t feel the efect from both sides ” (Female, 56). lifestyle (e.g. cycling, swimming, gardening, etc) or even
Participants could simply not tell if and how their sleep participating in sports competitions although sometimes
afected their pain or how their pain influenced the qual- they have had to resort to medication to ease the pain
ity of their sleep. As such, experiencing pain did not afterwards as one participant notes, “Yesterday I took part
stop them from having a good night’s sleep, neither did in an athletics competition (discus, javelin and hammer
having good quality sleep improve their perception of throw) and needed painkillers straight after” (Female, 67).
pain.
5.2.2. Weather, mattress, and sleep position</p>
        </sec>
      </sec>
      <sec id="sec-4-3">
        <title>In this short report, we wish to introduce a simple mobile</title>
        <p>It was clear from the responses that other factors beside application along with some preliminary evidence
speakLBP afected participants’ sleep. We noted that finding ing in favour of people being able to use it for providing
a “...good position to sleep” (Male, 40), a good support data about sleep, LBP and their relationship.
from the bed or mattress, and the need to “...turn during The exploratory nature of our study is aimed at
shedsleep” (Male, 38) were some of the concerns of a lot of ding more light on the LBP and sleep relationship
coparticipants. Participants also noted that the weather nundrum. Sleep Better with Back Pain helps capture
afected their sleep. This was particularly noticeable important self-reports on sleep and LBP that provides
reduring the summer months where participants expressed searchers with data and insights on this important health
a lack of or poor sleep due to hot weather. To some, issue. The long term plan is to build a community
powthe weather rather than their LBP afected their sleep, ered application for improving the lifestyles of people
“...my sleep last night was afected by the humid weather living with LBP through timely reminders,
recommendabut not by the back pain” (Female, 56). Another drew tions, and coaching to motivate people to make healthier
a connection between the weather and their felt pain, life choices that could improve both their low back pain
outlining how the heat could possibly be exacerbating and sleep quality.
the intensity of the felt pain, “...it’s mainly the heat that
is making other things harder to deal with” (Female, 67).</p>
        <p>Thus, to efectively manage one’s pain, environmental 6.1. Heterogeneity of Poor Sleep Factors
factors must also be considered.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>6. Discussion</title>
      <p>Overall, our results indicate the existence of a
negligible relationship between felt pain and how well-rested
participants felt in the morning. Indeed, this result is
interesting as it could be an indication that people
living with LBP have become so accustomed to their pain
such that it does not matter anymore. It is also an in- source treatments for LBP and people sufering from LBP
dication that the precise mechanisms that underpin the can suggest and view common LBP treatments used by
sleep and pain relationship remain unclear but are likely community members. We envision the app to become an
to involve multiple contributors such as depression [20], enabler of various studies with real users.
physical discomfort, neurotropic factors [29], as well as
psychological factors [19] among others. Despite the
pain felt prior to or during sleep, participants on average 7. Conclusion
sleep well. On the contrary, we notice the emergence
Our results show that the well-restedness of people
livof factors such as “sleep distruption”, “weather”, “active ing with LBP is influenced not only by pain at night but
leifefecsttoynle”h,o“wmewdeiclla-rtieosnte”,dapnedo“pslleeefepltpionsitthioenm”oarllnhinagv.inOgnean other factors such as sleep time, wake up time, and sleep
disruptions. We also indicate that people are willing to
such factor worth expounding on is “sleep distruption”.</p>
      <p>Sleep disruption afected significantly how well-rested donate their data toward sleep and LBP related research
participants felt in the morning despite the intensity of purposes. This study introduces a preliminary
investitheir pain during the previous night. Thus, while partic- gation into sleep tracking and low back pain using the
ipants’ perceived sleep quality was not afected by the “Sleep Better with Back Pain” app and communicates our
intensity of their pain at night, it was afected by the initial results to the academic community in hopes to
disruption of their sleep, disruptions which they identify spark interest and discussion within the community.
to be caused non-exhaustively by e.g. sleep movements,
bed or mattress, and environmental factors such as the Acknowledgments
weather.</p>
      <p>However, the connection of some of these factors to This research is connected to the GenZ strategic
profilpain is evident, e.g. sleep movements or uncomfortable ing project at the University of Oulu, supported by the
sleep positions lead to sleep disruptions because partici- Academy of Finland (project number 318930), and
CRITpants’ express feeling pain while moving in bed or laying ICAL (Academy of Finland Strategic Research, 335729).
in a particular position. Although participants often refer Part of the work was also carried out with the support of
to a factor such as sleep disruption as a major cause of Biocenter Oulu, spearhead project ICON.
their poor quality sleep, one possible underlying reason
for this disruption is their pain. The existence of and
possibly, interconnection of these heterogeneous factors References
in assessing the sleep and pain relationship calls for a
more holistic approach to investigating this issue.</p>
      <sec id="sec-5-1">
        <title>6.2. Limitations</title>
        <sec id="sec-5-1-1">
          <title>We acknowledge limitations in our initial exploration. We</title>
          <p>did not provide any form of reports, analytics, etc. nor
incentives for participation to participants of the study, a
possible reason for the low number of participants. Our
focus in this study is to ascertain the feasibility of the
core features of the app, and our results confirm that.
While this afects the generalizability of our results, we
argue that people have clear interest in LBP and sleep
and are willing to contribute their data towards research
in this sphere even when all they do is donate their data
without getting any insights in return.</p>
        </sec>
      </sec>
      <sec id="sec-5-2">
        <title>6.3. Towards a Future with LBP</title>
        <sec id="sec-5-2-1">
          <title>Work is currently underway with the “Sleep Better with</title>
          <p>Back Pain” app, with new features and user-interface (UI)
redesign. One such feature is the integration of daily,
weekly, and monthly analytics for all survey items (daily,
sleep, and quality of life surveys). We also foresee other
features like an in-app community where we could
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