Having Therapy During Sleep?: Improving Extinction Learning for … · One method of addressing this problem is to enhance therapeutic learning by ... participants listened to the

Running Head: SLEEP REHEARSAL OF EXTINCTION LEARNING 1

Having Therapy During Sleep?: Improving Extinction Learning for People with

Blood-Injection-Injury Fears by Rehearsing Memories During Sleep

Ki Eun Shin

Advisor: Richard E. Zinbarg

Second Reader: Ken A. Paller

I extend great thanks to Dr. Richard Zinbarg and Nehjla Mashal for their guidance and

support throughout all the stages of this process. I also thank Dr. Ken Paller.

This paper was supported by the Michael F. Dacey Research Grant from the Mathematical

Methods in the Social Sciences department of Northwestern University.

SLEEP REHEARSAL OF EXTINCTION LEARNING 2

Abstract

Patients often find exposure therapy aversive and sometimes have difficulty complying with

treatment. One method of addressing this problem is to enhance therapeutic learning by

capitalizing on memory consolidation during sleep. This study examined whether presenting

sounds associated with therapeutic information during sleep leads to greater symptom

reduction than exposure alone. Fourteen participants with blood-injection-injury fears

completed exposure and reflected on therapeutic lessons while listening to music. Half the

participants listened to the same music during their sleep for one week. Although not

significant, changes in participant ratings of anxiety and physical sensations in response to

fear-inducing stimuli were in the direction of superiority for the sleep rehearsal condition.

This suggests the possibility of augmenting exposure therapy with auditory-cued rehearsal of

therapeutic learning during sleep.

KEY WORDS: Exposure Therapy, Memory, Sleep, Blood-injection-injury Phobia


Having Therapy During Sleep?: Improving Extinction Learning for People

with Blood-Injection-Injury Fears by Rehearsing Memories During Sleep

People find it difficult to face their fears although it is often the necessary first step to

be free of them. The dilemma becomes most prominent for a person with a phobia, an

excessive and irrational fear of an object or situation that poses little or no actual threat. A

common treatment for phobias, exposure therapy, requires patients to experience the feared

object or situation in a safe setting, without the feared negative outcome. Despite the

confirmed efficacy of exposure (Craske, Kircanski, Zelikowsky, Mystkowski, Chowdhury &

Baker, 2008; Norton & Price, 2007), patients with phobias often find the therapy process

aversive, and thus are reluctant to fully comply with treatment. The phenomenon leads to a

dilemma that people who want to be treated have difficulty facing therapy. In order to resolve

this dilemma, it is necessary to find ways to enhance treatment outcome without incurring

emotional burden on patients.

This paper reviews difficulties with patient compliance in exposure therapy and

explores possible avenues for enhancing therapy outcome. Exposure is conceptualized as a

form of inhibitory learning (Bouton, 2002; Craske et al., 2008), and potential methods of

augmenting exposure learning are introduced with an emphasis on sleep rehearsal of memory.

The present research is outlined, which investigates whether sleep rehearsal augments

exposure learning and improves treatment outcome for people with blood-injection-injury

(BII) fears.

Problems with Exposure Therapy

Exposure therapy is a common treatment for phobias and other anxiety disorders.

However, despite its wide use and confirmed efficacy (Craske et al., 2008; Norton & Price,

2007), patients tend to find the treatment difficult to tolerate. The distress of the exposure

process can hinder the efficacy of exposure-based therapy, creating problems before and


during treatment. Even before the beginning of therapy, some patients choose to withdraw.

For instance, in a recent clinical trial for panic disorder, 5% of patients dropped out before

treatment (White, Allen, Barlow, Gorman, Shear, & Woods, 2010). Similarly, in an exposure-

based protocol for obsessive-compulsive disorder (OCD), pretreatment dropout was 6%,

(Whittal, Thordarson, & McLean, 2005). In an outpatient treatment for anxiety disorders, the

refusal rate reached 30.4% (Issakidis & Andrews, 2004).

Patients who decide to initiate therapy also may not complete the treatment. A

sizeable fraction of individuals with anxiety disorders do not remain in treatment (Huppert &

Baker-Morissette, 2003; Issakidis & Andrews, 2004; Leahy, 2001; Westen & Morrison,

2001). In an outpatient treatment for anxiety disorders, the dropout rate was 10.3% (Issakidis

& Andrews, 2004). Similarly, 14.5% of OCD patients (Whittal et al. (2005) and 15.6% of

patients with panic disorder (Öst, Thulin, & Ramnero, 2004) prematurely terminated their

treatment in an exposure-based cognitive behavioral therapy. In a clinical trial for panic

disorder, the patient dropout rate was 19%, and patients dropped out most frequently after

treatment sessions entailing exposure (White et al., 2010). A meta-analysis of cognitive-

behavioral treatment for social phobia shows that an average of 16.4% (SD = 7.4, across 8

studies) of patients receiving exposure therapy dropped out (Taylor, 1996).

In addition, patient compliance rates among those who remain in therapy tend to be

low in exposure therapy (Abramowitz, Franklin, Zoellner, & DiBernardo, 2002; Foa et al.,

1983; Scott & Stradling, 1997; Simpson, Huppert, Petkova, Foa, & Liebowitz, 2006). In a

clinical trial for posttraumatic stress disorder (PTSD), only 57% of participants followed the

therapist’s directions for daily exposure homework (Scott & Strandling, 1997). Participant

compliance matters because it affects treatment response (Issakidis & Andrews, 2004). Better

compliance predicts greater improvement in post-treatment functioning (Mischelson,

Mavissakalian, Marchione, Dancu, & Greenwalk, 1986) and long-term maintenance of


treatment gains (Park, Mataix-Cols, Marks, Ngamthipwatthana, Marks, Araya, & Al Rescorla,

2001). On the other hand, low compliance can lead to suboptimal therapy outcome despite

completion of treatment (Sanderson & Bruce, 2007).

Enhancing Exposure Therapy

Exposure therapy has been widely conceptualized as a form of inhibitory learning

(Bouton, 2002; Craske et al., 2008). Phobias are considered to be often a product of fear

conditioning in which an individual develops a negative association for an object or situation

and becomes fearful of related stimuli (Bouton, 2002; Craske et al., 2008). Exposure therapy

may alleviate fears by inducing new inhibitory learning rather than deleting or weakening

previous excitatory (fearful) learning (Bouton, Woods, & Pineno, 2004; Rescorla, 2001). The

fearful association remains intact, but the newly learned safety association competes with the

old fear learning (Bouton, 2002). Successful exposure treatment occurs when the new

association becomes a dominant response to the once fear-inducing stimuli. The

establishment of new safety association is called extinction.

Based on the learning mechanism of extinction, previous attempts to enhance

exposure therapy focused on memory consolidation and retrieval of inhibitory learning

(Craske et al, 2008). One line of research examined effects of varying phobic stimuli and

spaced scheduling of exposure sessions on treatment outcome. Varying phobic stimuli in

exposure sessions helps patients remember the learned information better because it provides

multiple memory cues instead of a single cue (Bjork, 1988; Bjork & Bjork, 1992; Magill &

Hall, 1990). For instance, one study showed that exposure to varied phobic stimuli (i.e.,

multiple spiders) led to better maintenance of treatment gains at follow-up than did exposure

to the same stimulus (i.e., a single spider) (Rowe & Craske, 1998).

Another method is to space out exposure sessions over a longer time period rather

than to cluster them over a short time period. Spaced learning trials improve retrieval of


learned information (Fanselow, DeCola, & Young, 1993; Josselyn et al., 2001; Kogan et al.,

1997; Scharf et al., 2002) possibly because partial forgetting between the learning trials leads

to greater storage strength of the memory (Bjork & Bjork, 1992). For instance, spaced

exposure (20 minutes on 4 days) produced better treatment response than massed exposure

(40 minutes on 2 days) for specific phobia (Ramsay, Barenda, Breuker, & Kruseman, 1966).

However, there are also discrepant findings. In another study (Foa, Jameson, Turner, & Payne,

1980), massed (daily) rather than spaced (weekly) exposure sessions led to greater symptom

reduction in individuals with agoraphobia. Many other studies did not find a significant

difference between massed and spaced exposure schedules (Berah, 1981; Chambless, 1990;

Ning & Liddell, 1991).

Supplementing exposure therapy with a biochemical substance such as D-cycloserine

(DCS) has been also explored. DCS has been shown to enhance consolidation of extinction

learning in both animals (Richardson, Ledgerwood, & Cranney, 2004; Santini, Muller, &

Quirk, 2001; Woods & Bouton, 2006; Davis, 2002) and humans (Ressler et al., 2004; Davis,

Ressler, Rothbaum, & Richardson, 2006). The use of DCS in exposure therapy led to better

maintenance of treatment gains at both post-treatment and follow-up compared with a

placebo condition (Norberg, Krystal, & Tolin, 2008). Other biological agents such as

yohimbine and glucocorticoid cortisone also improved treatment outcome in claustrophobia

and social phobia respectively (Powers, Smits, Otto, et al., 2009; Soravia, Heinrich, Aerni, et

al., 2006). However, despite the initial promising results, the effect of DCS does not always

appear significant (Guastella, Dadds, Lovibond, Mitchell, & Richardson, 2007). Thus, further

evaluation is necessary to elucidate the role of DCS in extinction learning.

Sleep, Memory, and Extinction

The literature on sleep and memory suggests another way to enhance extinction

learning. Previous studies showed that sleep aids in encoding and consolidation of new


memories (especially emotional memories; Walker, & van der Helm, 2009) and may

facilitate integration of new memories with old ones (Diekelmann & Born, 2010; Walker &

Stickgold, 2010). Researchers have also demonstrated that sleep generalizes the extinction

response to novel phobic stimuli not specifically targeted in an exposure session (Pace-Schott

et al., 2009). In this study, participants were conditioned to fear two differently colored lamps

using mild electric shocks. Experimenters extinguished participants’ fear response to one of

the lamps by repeatedly presenting the lamp without shocks. Later, the fear conditioning was

measured by skin conductance response, and participants who slept for twelve hours showed

decreased fear response to both the extinguished and unextinguished stimuli whereas those

who stayed awake for twelve hours showed decreased fear response only to the extinguished

stimulus.

A recent study provides an insight on how to apply enhancing memory consolidation

during sleep to exposure therapy (Rudoy, Voss, Westerberg, & Paller, 2009). In this study,

participants saw 50 images, individually appearing on different parts of a computer screen

and memorized the images’ locations. When an image appeared on a screen, a related sound

was played (e.g. cat-meow). Later, participants took a nap, and their brainwaves were

measured by EEG equipments. During slow wave sleep, half of the 50 different sounds were

replayed. The result showed better recall of the images cued by related sounds during sleep

than those not cued during sleep.

Similar methodology can be applied to exposure therapy. If cued sleep enhances

extinction learning as it did for spatial memory learning, it would have meaningful clinical

applications. For instance, the number of exposure sessions necessary to achieve symptom

reduction might decrease because a part of the work can be done during sleep outside

sessions. As the sleep rehearsal would cause less emotional distress than actual exposure

sessions, previously reluctant patients might be more willing to initiate, engage in, and


remain in therapy. Noncompliant patients may still be able to achieve desirable treatment

outcomes with reinforced learning during sleep. Furthermore, continued use of auditory

enhancement during sleep might help patients to maintain treatment gains for a longer time

period, preventing early relapse.

A previous study (Panton, 2011) examined effects of sleep rehearsal on treatment

outcome of exposure therapy for blood-injection-injury (BII) phobia. BII phobia refers to an

intense fear and avoidance of blood and blood-related items or events such as needles,

injections, injuries, and surgeries (Sarlo et al, 2008). In this study, participants with BII fears

completed an exposure session and after the session, listened to a music clip while reviewing

the exposure learning. Participants in the sleep rehearsal condition were instructed to listen to

the same music clip during their sleep at each night for one week. The study compared

degrees of symptom reduction in the sleep rehearsal condition and the control condition.

The result showed a trend in the direction of superiority for the sleep rehearsal

condition to the control condition, but the difference was not significant (Panton, 2011). Two

limitations of the study may account for the non-significant result. Participants were from the

Introduction to Psychology student pool, who participated to fulfill their class requirement.

Because they did not voluntarily choose to participate in the study, participants might have

had little motivation to complete the daily assignments for sleep rehearsal. In addition, the

study solely relied on participants’ self-reports for a manipulation check, thus lacking other

objective measures to test the reports’ accuracy.

The Present Research

The current study aimed to replicate the previous research by Panton (2011) and

explore whether adding sounds presented during encoding of therapeutic information and

later presented during sleep leads to greater symptom reduction than exposure alone. The

current study focused on exposure therapy for BII phobia for two practical reasons: 1) BII


phobia can be effectively treated by one exposure session of three to five hours (Öst, 1989),

and 2) the phobic stimuli to be used in sessions are more readily available for BII phobia than

for other phobias (e.g. images of blood vs. housing a spider). The goal of the current study

was to address limitations of the previous study (Panton, 2011). Improvements from the

previous study included participant recruitment from community samples instead of

Introduction to Psychology student pool and addition of a manipulation check (the play

counts in an MP3 player). In addition, the previous music clip was modified to have more

positive valence, and white noise was inserted at the beginning of the clip for sleep rehearsal

to facilitate sleep.

Method

Participants

Fourteen participants (5 male, 9 female) were recruited in the Northern Chicagoland

area via online advertisements, newspaper advertisements, and posted flyers. Participants

were pre-selected based on a 15-minute structured clinical interview to determine whether

they met the DSM-IV-TR criteria for specific phobia, Blood-Injection-Injury (BII) Type.

Block randomization was used to pair up participants and assign half the pairs to the sleep

rehearsal condition, and the other half to the control condition. The age of participants ranged

from 18 to 73 years (M = 32.1, SD = 14.5). Eighty percent of participants identified

themselves as Caucasian, 13% East Asian, and 7% African American. All participants

received $20.00 compensation at the end of the study.

Materials

Diagnostic Interview. To determine eligibility for this study, a graduate student

trained in administration of the Structured Clinical Interview for DSM-IV-TR Axis I

Disorders (SCID I; First, Spitzer, Gibbon, & Williams, 2002) interviewed potential

participants. The interview included the specific phobia section of the SCID, which indicated


whether participants met the DSM-IV TR criteria for specific phobia, Blood-Injection-Injury

(BII) Type. The criteria include excessive and persistent fear of BII related situations (e.g.

surgery, venipuncture) and anxiety upon encountering such situations. The person either

avoids the situations or endures them with considerable distress. He or she also perceives the

fear as irrational or excessive, and the fear and avoidance cause functional impairment (e.g.

reluctance to receive necessary medical care).

Self-report Measures of BII Fear. Participants filled out three questionnaires in the

pre and the post session: The Mutilation Questionnaire (MQ), the Blood-Injection Symptom

Scale (BISS), and nine items from the Fear Survey Schedule (FSS). The MQ (Klorman,

Weerts, Hastings, Melamed, & Lang, 1974) is a 30 true/false item questionnaire that

measures the verbal/cognitive component of mutilation and BII fear (e.g. “I dislike looking at

pictures of accidents or injuries in magazines”). The MQ has been used as a predictor of BII

phobia and fainting (Kleinknecht, & Thorndike, 1990; Oliver & Page, 2008). The BISS (Page,

Bennett, Carter, Smith, & Woodmore, 1997) is a 17 item yes/no questionnaire measuring

phobic symptoms experienced in situations involving blood or injections (e.g. “Were you

dizzy or lightheaded?”). The nine items from the FSS (Wolpe & Lang, 1974) measure

fearfulness for BII-related stimuli (e.g. “Open Wounds,” “Receiving Injections”) on a 7-point

scale (0 = None, 3 = Some fear, 6 = Terror).

Behavioral Avoidance Task (BAT). A 10-minute behavioral avoidance task (BAT)

was used in the pre and the post session to measure levels of fear and anxiety. In the BAT,

participants saw each of the 12 pictures related to BII fears on a computer screen (e.g. a

picture of a syringe or open wounds). The task began with the least fear-inducing image, and

at each step, images became progressively more fear-inducing. Throughout the task,

participants proceeded at their own pace. When participants felt uncomfortable or unwilling

to continue, they could exit the BAT. Fear was measured by the number of steps participants


made during the BAT. A greater number of completed steps meant a lower level of BII fears.

The BAT paradigm has been successfully used in other studies on specific phobia (Oliver &

Page, 2008; Tsao & McKay, 2004) to compare the pre- and the post-treatment levels of fear.

During the BAT, participants’ looking time was measured to examine gaze aversion.

Exposure to fear-related stimuli in individuals with phobias leads to visual avoidance (Tolin,

Lohr, Lee, & Sawchuk, 1999). The looking time was measured via each participant’s reaction

time during the BAT, aggregated across the 12 pictures. The longer looking time indicated

less visual avoidance.

Subjective Units of Distress Scale (SUDS) & Physiological Rating. During the

BAT and the exposure tasks, a Subjective Units of Distress Scale (SUDS; Wolpe, 1969) and

a 10-point scale for physiological sensations were used to measure within- and between-

session changes in fear reduction. After viewing each picture in the BAT and completing an

exposure task, participants rated their level of distress on a SUDS from 0 (no fear) to 10

(highest fear) and also rated the intensity of physiological sensations (e.g. nausea or light-

headedness) on a scale from 0 to 10. The SUDS rating indicates the subjective level of

distress experienced by an individual (Wolpe, 1969). The scale has been used to evaluate

treatment progress in studies on posttraumatic stress disorder, obsessive-compulsive disorder,

and specific phobia (Devilly & Spence, 1999; Oliver & Page, 2008; Taylor, 1998).

Procedure

This study included the pre and the post sessions, administered a week apart. To have

an equal number of participants in each condition, block randomization was used.

Experimenters paired up participants and randomly assigned one person from each pair to the

sleep rehearsal condition, and the other, to the control condition.

Pre Session. Participants came to the lab and first filled out the informed consent

forms. Participants also filled out a questionnaire packet including the MQ, the BISS, and the


FSS. The experimenter provided brief explanation about BII phobia and exposure therapy

and introduced the Behavioral Avoidance Task. For the next ten minutes, participants

completed the BAT, viewing 12 BII-related images and rating their level of distress and

physiological sensations on the SUDS and the 10-point physiological sensation scale.

Throughout the BAT, participants’ faces were video recorded using a 9000 Logitech camera.

Participants then moved to another room and began the exposure session. The

exposure session consisted of four tasks in the order of the least to the most anxiety-

provoking. The first task involved watching three brief videos of blood and surgery. The task

continued until participants felt comfortable watching the most fear-inducing video. The

second task was holding a bag of stage blood for as long as participants felt comfortable. In

the third task, participants watched a set of needles while the experimenter held them in her

hand, and they also held the needles themselves. The last task involved watching the

experimenter prick herself with a sterile mini lancet. Participants who were willing also

pricked themselves with a lancet. After each task, participants rated their level of distress and

physiological sensations on the SUDS and the physiological sensation scale. Throughout the

exposure session, participants proceeded at their own pace and could stop at any point they

felt uncomfortable. The entire exposure session took approximately 40 minutes.

After the exposure session, participants reflected on the exposure tasks for 10

minutes. The experimenter guided them by going over each task and benefits of the exposure

experience. During the reflection period, participants listened to a music clip in the

background. The music was a novel piece created for the use in this study and had neutral to

positive valence. After the reflection period, participants in the control condition left, and

those in the sleep rehearsal condition received instructions for sleep rehearsal. The

experimenter gave them a sleep record sheet and an MP3 player with a music clip. The clip


included white noise for the first 30 minutes, and the rest was 6 hours of the same music

participants listened to during the reflection period.

Sleep Rehearsal. For one week after the pre session, participants in the sleep

rehearsal condition were instructed to listen to the clip during their sleep at each night. They

recorded on the sleep record sheet the time they went to sleep and woke up and the hours they

listened to the clip. The self reports were later compared with the music play counts

automatically stored in the MP3 player distributed to participants.

Post Session. After one week from the pre session, participants visited the lab again.

For the sleep rehearsal condition, the experimenter retrieved the MP3 player and the sleep

record sheet. As in the pre session, participants filled out a questionnaire packet of the MQ,

the BISS, and the FSS. Participants also completed the second BAT with the same 12 images

used in the first BAT and provided the SUDS and physiological sensation ratings. After the

BAT, the experimenter verbally debriefed participants and answered if they had any question.

Results

Manipulation Check

Participant self-reports and MP3 player play counts were used as a manipulation

check. Seven participants in the sleep rehearsal condition recorded on the sleep record sheet

duration of their sleep and the number of hours they listened to the clip each night. MP3

player play counts were used to measure how many times each participant listened to the

music clip. Due to a technical failure, the play counts were only collected from four

participants in the sleep rehearsal condition.

According to self-reports, participants in the sleep rehearsal condition listened to the

music clip for 25.4 hours on average (SD = 22.4). See Figure 1 for the distribution of self-

reported listening hours. For the four participants from whom both measures were collected,

there was a discrepancy between self-reports and play counts (see Figure 2). According to


self-reports, the participants listened to the music clip for 19.6 hours on average (SD = 21.6).

According to play counts, they listened to it for 13.7 hours on average (SD = 21.5). Based on

self-reports and play counts, three participants in the sleep rehearsal condition listened to the

clip for less than three hours. Because the three participants clearly did not receive the

manipulation as intended, their data was excluded from analysis.

Subjective Distress Rating & Physiological Rating.

We predicted that the sleep rehearsal condition would show a greater pre to post

decrease in subjective distress and physiological ratings than controls. Independent samples t-

tests with an alpha level of .05 did not reveal a significant effect of group for the pre to post

changes in subjective distress and physiological ratings. However, the group difference was

in the direction of superiority for the sleep rehearsal condition, t(9) = -.98, p = .35, d = .67

and t(9) = -1.59, p = .15, d = 1.01, respectively. Whereas participants in the control condition

showed a mean decrease of .71 in subjective distress ratings (SD = 1.55) and of -.07 in

physiological ratings (SD = 1.43), participants in the sleep rehearsal condition showed a mean

decrease of 1.75 in subjective distress ratings (SD = 1.94) and of 1.38 in physiological ratings

(SD = 1.49).

Looking Time & Self-report Questionnaires

We predicted that the sleep rehearsal condition would also show a greater pre to post

increase in looking time and a greater pre to post decrease in self-report measures of BII fears

than controls. Independent samples t-tests with an alpha level of .05 did not reveal significant

differences between the control and the sleep rehearsal condition. Participants in the control

condition showed a mean decrease of 1936.64 in looking time (SD = 6755.30), and

participants in the sleep rehearsal condition showed a mean decrease of 3603.50 in looking

time (SD = 6491.30), t(9) = .40, p = .70, d = .25. Participants in the control condition also

showed a mean decrease of .49 in the Fear Survey Schedule scores (SD = .70) and a mean


increase of .01 in the Blood-Injection Symptom Scale scores (SD = .09) whereas participants

in the sleep rehearsal condition showed a mean decrease of .64 in the FSS scores (SD = 1.17)

and a mean increase of .03 in the BISS scores (SD = .25), t(9) = -.28, p = .79, d = .21 and t(9)

= .17, p = .87, d = .22, respectively. However, results concerning the Mutilation

Questionnaire were in the direction of superiority for the sleep rehearsal condition, t(9) = -

1.66, p = .13, d = 1.67. While participants in the control condition had a mean decrease of .05

(SD = .09), participants in the sleep rehearsal condition had a mean decrease of .20 in MQ

scores (SD = .22).

Discussion

The present study aimed to investigate whether the addition of music presented

during encoding of therapeutic information and later, during sleep, enhances the outcome of

exposure. Results failed to support that exposure with auditory-cued sleep rehearsal leads to

superior treatment outcomes compared to exposure alone. However, because of the low

participant compliance and restricted sample size, the current study did not provide an

adequate test of the hypotheses. The lack of an effect might be due to insufficient

manipulation of the variable of interest and/or low statistical power. Given that results were

generally in the direction of superiority for the sleep rehearsal condition, a future study with a

larger sample size and better implementation of the manipulation is warranted.

Another limitation of this study involves lack of facial coding data. Participants’ faces

were video-recorded to examine gaze aversion and facial disgust during Behavioral

Avoidance Task, but the data could not be included in this report as the coding is not yet

complete. In the current study, looking time was measured via reaction times during

Behavioral Avoidance Task. However, individuals with phobias tend to avert their eyes from

fear-inducing stimuli (Tolin et al., 1999), and therefore, it is necessary to record duration of

visual avoidance during BAT and adjust the reaction time to obtain a more accurate measure


of looking time. In addition, previous studies showed that disgust, rather than fear, is a

dominant response of people with BII fears during pictorial exposure to blood and bodily

injury (Olantunji, Lohr, Sawchuk, & Patten, 2007). Thus, facial coding of participants’

disgust reactions during BAT would have been a useful measure of pre-to-post symptom

reduction in addition to subjective distress and physiological ratings.

One of the goals of the current study was to improve on a past study (Panton, 2011)

by addressing the problem of low participant compliance by recruiting from a different pool

of subjects. In the previous study (Panton, 2011), participants were recruited from the

Introduction to Psychology student pool, who participated to satisfy research participation

requirements for the class. In the current study, participants were recruited from the

community to better ensure that participants were interested in reducing their fears and

motivated to listen to the clip during sleep each night for a week. However, recruiting from

the community instead of the Introduction to Psychology student pool did not lead to greater

participant compliance. According to participant self-reports, the participants in the sleep

rehearsal condition listened to the clip for 3.6 hours per day on average. Three participants in

the sleep rehearsal condition listened to the clip for less than three hours during a week. As a

result of low participant compliance, the study failed to provide an adequate test of whether

listening to sounds associated with therapeutic information during sleep leads to greater

symptom reduction than exposure alone.

Different factors may account for the low participant compliance in the current study.

First, some participants might not have been interested in reducing their fears and therefore

were not motivated enough to comply with the experimental protocol. When asked during the

post session, several participants answered that their primary reason for participating was

monetary compensation rather than overcoming their fears. Alternatively, participants might

have found it uncomfortable to listen to the clip during sleep or had difficulty falling asleep


because of the sounds. In addition, participants could have associated the music clip with

aversive experiences of exposure and were thus reluctant to listen to it during sleep. In the pre

session, participants completed exposure tasks and had a reflection period to review positive

therapeutic gains from the tasks while simultaneously listening to a music clip. The purpose

of the reflection period was to establish an association between therapeutic learning and the

music clip. However, reflecting on therapeutic gains might have reminded participants of

their anxiety during the exposure tasks, resulting in an association between the music clip and

anxiety as well as therapeutic learning. Given that emotional salience enhances memory

(Parent et al., 2011), strong emotions such as fear or disgust could have been paired more

strongly with the clip than therapeutic learning. As a result, participants might have been

reluctant to listen to the clip because it reminded them of aversive experiences of exposure.

Depending on its potential cause, the low participant compliance of this study has

different implications for the use of auditory-cued sleep rehearsal in a therapeutic setting. If

the reason for the low compliance is lack of motivation in participants, there is a potential for

better compliance in a therapeutic setting. Patients participating in actual therapy are

treatment-seekers who are motivated to overcome their fears and thus, are likely to comply

with the instruction better. On the other hand, if the low compliance is due to discomfort

during auditory-cued sleep rehearsal or the music clip’s evocation of anxiety, patients are less

likely to show improved compliance in a therapeutic setting. If patients find the experience of

auditory-cued sleep rehearsal uncomfortable or anxiety-provoking, despite their desire to

overcome fears, they might not be willing to comply with the intervention. These possibilities

raise questions about feasibility of implementing auditory-cued sleep rehearsal in a

therapeutic setting. Although the current study lacked a sufficient sample size to confirm

whether auditory-cued sleep rehearsal is effective, the low compliance rate casts doubt on

whether auditory-cued sleep rehearsal is a practical method of augmenting exposure therapy.


Despite the possibly limited therapeutic application, however, a future study on

auditory-cued sleep rehearsal of therapeutic learning would still be valuable. It can contribute

to the understanding of the relationship between extinction learning (exposure) and memory

consolidation during sleep. In conducting such a study, it is necessary to address limitations

of the current study by using a larger sample and changing the experimental protocol to

ensure that manipulation is delivered. One way to implement the manipulation, independent

of participant motivation for compliance on their own would be bringing in participants to a

lab to take a nap (e.g. Lau, Alger, & Fishbein, 2011; Spoormaker et al., 2010).

If a larger sample size and successful implementation of manipulation leads to an

enhancement effect, the result would replicate previous findings that sleep plays a role in

memory consolidation of extinction learning (Pace-Schott et al., 2009; Spoormaker et al.,

2010). The result would also illuminate the application of the auditory-cued sleep rehearsal

paradigm to different kinds of learning other than spatial memory learning (Rudoy et al.,

2009).

Overall, the results of the present study failed to support the hypothesis that listening

to sounds associated with therapeutic learning leads to greater symptom reduction than

exposure alone. However, due to limitations of the study, including low participant

compliance and small sample size, the current study did not provide an adequate test of this

hypothesis. Given that some of the results were in the direction of superiority for the sleep

rehearsal condition, future research should be conducted to confirm the effectiveness of

auditory-cued sleep rehearsal, with a larger sample size and more effective implementation of

the manipulation. In addition, the low participant compliance in a past study (Panton, 2011)

and the current study suggests that auditory-cued sleep rehearsal needs to be carefully

thought through before it could be a viable method of augmenting exposure therapy.


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Figure 1. Histogram of self-reported listening hours in the sleep rehearsal condition.

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Figure 2. Number of listening hours based on self-reports and play counts for four

participants in the sleep rehearsal condition.

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Documents

Having Therapy During Sleep?: Improving Extinction Learning for … · One method of addressing this problem is to enhance therapeutic learning by ... participants listened to the