Cognitive-Behavioral Therapy for Insomnia Co-Morbid with Hearing Impairment: A Randomized Controlled Trial

Cognitive-Behavioral Therapy for Insomnia Co-Morbidwith Hearing Impairment: A Randomized Controlled Trial

Markus Jansson-Frojmark • Steven J. Linton •

Ida K. Flink • Sarah Granberg • Berth Danermark •

Annika Norell-Clarke

Published online: 10 February 2012

� Springer Science+Business Media, LLC 2012

Abstract The purpose of the current study was to examine

the effects of cognitive behavior therapy (CBT-I) for

insomnia on patients with insomnia co-morbid with hearing

impairment. A randomized controlled design was used with a

3-month follow-up. Thirty-two patients with insomnia co-

morbid with hearing impairment were randomized to either

CBT-I or a waitlist condition (WLC). The primary outcome

was insomnia severity. Secondary outcomes were sleep diary

parameters, dysfunction, anxiety, and depression. Compared

to WLC, CBT-I resulted in lower insomnia severity at post-

treatment and at follow-up (d = 1.18–1.56). Relative to

WLC, CBT-I also led, at both assessment points, to reduced

total wake time (d = 1.39) and increased sleep restoration

(d = 1.03–1.07) and sleep quality (d = 0.91–1.16). Both

groups increased their total sleep time, but no significant

group difference emerged. Compared to WLC, CBT-I

resulted in higher function (d = 0.81–0.96) and lower anx-

iety (d = 1.29–1.30) at both assessment points. Neither

CBT-I nor WLC led to improvement on depression. Based

on the Insomnia Severity Index, more CBT-I (53–77%) than

WLC participants (0–7%) were treatment responders. Also,

more CBT-I (24%) than WLC participants (0%) remitted. In

patients with insomnia co-morbid with hearing impairment,

CBT-I was effective in decreasing insomnia severity, sub-

jective sleep parameters, dysfunction, and anxiety. These

findings are in line with previous results on the effects of

CBT-I in other medical conditions.

Keywords Insomnia � Hearing impairment � Tinnitus �Cognitive behavior therapy � Co-morbidity

Introduction

The defining characteristics of insomnia are complaints of

poor, insufficient, or unsatisfactory sleep with accompa-

nying daytime dysfunction (American Psychiatric Associ-

ation [APA], 2000). Insomnia can be a distinct disorder,

which is labeled primary insomnia in the DSM-IV-TR

system (APA, 2000), and *16% of individuals with

insomnia symptoms fulfill criteria for primary insomnia

(Ohayon, 1997). Several meta-analyses and reviews have

been presented concerning the effects of cognitive-behav-

ioral therapy for insomnia (CBT-I), most commonly for

primary insomnia. Based on one of these reviews (Morin

et al., 2006), behavioral and CBT-I resulted in reliable

sleep improvements, and these improvements were also

concluded to be well sustained over time.

Insomnia can also be secondary to or co-morbid with

medical and psychiatric conditions. In the present DSM-

IV-TR system, the term used is secondary insomnia, which

means that (a) a stimulus (e.g. cancer) must precede

insomnia, (b) a variation in frequency, severity, or duration

of the stimulus is strongly associated with variation in

insomnia, and (c) in the absence of variation in the

stimulus insomnia is invariant (Lichstein, 2006). The

term co-morbid insomnia, which is likely to appear in the

forthcoming DSM-V system (Ellis, Gehrman, Espie,

M. Jansson-Frojmark (&) � S. J. Linton �I. K. Flink � A. Norell-Clarke

School of Law, Psychology, and Social Work, Orebro

University, SE-701 82 Orebro, Sweden

e-mail: [email protected]

S. Granberg � B. Danermark

The Swedish Institute for Disability Research, Orebro

University, Orebro, Sweden

S. Granberg � B. Danermark

Audiological Research Centre, Orebro University Hospital,

Orebro, Sweden

123

J Clin Psychol Med Settings (2012) 19:224–234

DOI 10.1007/s10880-011-9275-y

Riemann, & Perlis, in press), denotes that the requirements

for secondary insomnia are substantially absent, indicating

that insomnia co-exists with another condition in a

dynamic fashion. While secondary insomnia is probably

rare (Lichstein, 2006), co-morbid insomnia is likely to be

very common. For example, *60% of individuals with

insomnia symptoms in one study met criteria for co-morbid

insomnia (Ohayon, 1997).

A significant overlap has been demonstrated between

insomnia and various medical problems, including chronic

pain, high blood pressure, and gastrointestinal problems

(Taylor et al., 2007). Despite the high co-occurrence

between insomnia and medical conditions, research on

treatment effects for patients with insomnia co-morbid with

medical disorders is still lacking (Morin et al., 2006; Smith,

Huang, & Manber, 2005). One possible reason to the

limited attention to the treatment of co-morbid insomnia

may be due to the traditional notion that the co-morbid

insomnia will not respond to treatment unless the associ-

ated condition is treated first (Stepanski & Rybarczyk,

2006). This notion has however been challenged based on

treatment findings showing that CBT-I is effective also for

secondary insomnia and epidemiological research demon-

strating that insomnia is a potent risk factor for condi-

tions that commonly co-exist with insomnia, e.g.

depression, cardiovascular disorders, and pain (Stepanski

& Rybarczyk, 2006).

To our knowledge, only four trials have focused upon

the effects of administering CBT-I to patients with

insomnia co-morbid with medical conditions. In one trial

on patients with insomnia associated with chronic pain,

CBT-I was more effective than a waitlist control (WLC) on

sleep onset latency, wake after sleep onset, and sleep

efficiency, but not on number of awakenings, total sleep

time (TST), pain, depressive symptoms, and medication

use (Currie, Wilson, Pontefract, & deLaplante, 2000). In a

second RCT on older patients with insomnia associated

with various medical illnesses (e.g. heart conditions,

osteoarthritis, and pulmonary disease), CBT-I and relaxa-

tion were more effective than a delayed-treatment control

on several indices of sleep improvements, including wake

after sleep onset, sleep efficiency, and overall sleep quality,

but there were no group differences on medication use,

anxiety, depression, and quality of life (Rybarczyk, Lopez,

Benson, Alsten, & Stepanski, 2002). In a third RCT on

older patients with insomnia co-morbid with osteoarthritis,

coronary heart disease or pulmonary disease, CBT-I was

more effective than a placebo condition on sleep parame-

ters, global sleep quality, and sleep impairment (Rybarczyk

et al., 2005). No group differences were documented for

depression, distress, health, and pain. In a fourth RCT on

patients with insomnia co-morbid with cancer (active

therapy completed), CBT-I was superior to treatment-as-

usual on sleep onset latency, wake time after sleep onset,

anxiety, depression, cancer-related quality of life, and

fatigue, but not on TST (Espie et al., 2008). Conclusively,

the literature thus suggests that CBT-I is both a feasible

and effective treatment option for patients with insomnia

co-morbid with medical conditions. However, given the

small number of trials and the limited medical conditions

that so far have been studied, the effects of CBT-I for

patients with both insomnia and medical conditions still

warrants further research (Morin et al., 2006; Smith et al.,

2005).

According to a few sources, sleep complaints appear to

be common among individuals with tinnitus and hearing

impairment. Among patients with tinnitus, insomnia is

often reported as the difficulty most frequently mentioned

(Axelsson, & Ringdahl, 1989). Among elderly individuals

in the community with tinnitus, the prevalence of insomnia

was high at 51.9% in one study (Lasisi & Gureje, 2011). In

addition, tinnitus appears to be more severe in tinnitus

patients with insomnia (Axelsson, & Ringdahl, 1989). On

the other hand, findings indicate that objective sleep

parameters do not differ when comparing insomnia patients

with and without tinnitus (Cronlein, Langguth, Geisler, &

Hajak, 2007). In one investigation among those with a

hearing impairment, sleep complaints were as common as

9–39% for men and 23–57% for women (Danermark &

Gellerstedt, 2004). Sleep complaints were particularly

prevalent among those who had a type of work that was

characterized by high stress (high in demand and low in

control). In a second study, sleep problems were as pre-

valent as 49.6% among individuals with a hearing loss

(Dalton et al., 2003). In a third study about sleepiness and

sleep in elderly subjects, it was discovered that older adults

with impaired hearing reported poor sleep, more frequent

awakenings and more difficulty falling asleep, more often

than older adults with normal hearing (Asplund, 2003). The

above findings suggest that sleep complaints are highly

prevalent among those with tinnitus, hearing impairment or

loss. The results also indicate that insomnia is associated

with more tinnitus distress and that insomnia is possibly a

stand-alone condition, suggesting that testing interventions

for insomnia among those with hearing impairment is an

important therapeutic route. To date, no efforts have

however been made to study the effects of sleep inter-

ventions for this patient group.

The purpose of investigation was to examine the effects

of CBT-I, in comparison with a waitlist control group, for

patients with insomnia co-morbid with hearing impairment.

More specifically, the aim was to compare the two groups

over time on insomnia severity, sleep parameters, dys-

function, anxiety, and depression.

J Clin Psychol Med Settings (2012) 19:224–234 225

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Methods

Overview of the Design

A randomized controlled trial with assessments at pre-

treatment, post-treatment, and at a 3-month follow-up

compared the effects of CBT-I with a waitlist control

group. All participants were free to pursue treatment as

usual in the health care system. The study was approved by

the Centre for Research Ethics in Uppsala, Sweden.

Participants

Potential participants were recruited from two audiology

clinics that offered treatment to patients with hearing dif-

ficulties and via the member journal (Auris) of the Swedish

Association of Hard of Hearing People. The clinic

recruitment started in January 2008 and was completed in

May 2009. Each consecutive patient that visited the clinics,

either for assessment or treatment, was contacted. The

candidates were initially informed about the project and

asked about whether they had had insomnia complaints

(difficulties with sleep initiation, sleep maintenance, early

morning awakenings, non-restorative sleep, or poor sleep

quality) during the past 6 months and were willing to

participate in the project (94 individuals did so) (Edinger

et al., 2004). If these criteria were met, a sleep diary to be

filled out during 1 week and a return envelope was

administered. In addition, each candidate was given an

information letter, which described the project in detail and

ethical guidelines. The journal recruitment was executed

during the fall 2008 and consisted of an article in the

journal about the study and a call for candidates to contact

our research group (15 individuals did so). The recruitment

process was otherwise identical for the two patient pools.

When the sleep diary was returned to the project group,

sleep onset latency and wake time after sleep onset were

summed and averaged over the 7-day period. The potential

participant was contacted via telephone if the following

criterion was met according to the sleep diary (n = 62):

sleep onset latency and/or wake time after sleep onset

longer than 31 min during three nights or more the past

week (Lichstein, Durrence, Taylor, Bush, & Riedel, 2003).

Among the 32 participants who did not fulfil the sleep diary

criteria, 11 were excluded due to insufficient insomnia

complaints and 21 due to not returning the sleep diary.

During the telephone call with the 62 remaining partici-

pants, the following inclusion criteria were checked: (1)

age between 18 and 65 year, (2) duration of insomnia

symptoms of 6 months or more, and (3) hearing impair-

ment. During the telephone call, the interviewer also

checked that the insomnia symptoms caused daytime

impairment along with questions about sleep-interfering

circumstances [i.e. psychiatric symptoms, medical condi-

tions, medications, drugs, substances, beverages, other

sleep disorders, and severe tinnitus distress (using the

Klockhoff and Lindblom (1967) grading system (Anders-

son, Lyttkens & Larsen, 1999), patients with Grade III

tinnitus, i.e. the tinnitus sound is constantly present and is

impossible to ignore and the afflicted person is to a very

large extent distressed by the tinnitus sound, were exclu-

ded]. At this stage, 26 individuals were excluded [reporting

severe tinnitus distress or pain as the cause for the insomnia

complaints (n = 10), not longer interested in the project or

time constraints to participate (n = 9), could not be

reached (n = 2), not reporting daytime impairment due to

insomnia symptoms (n = 2), reporting sleep apnea as the

primary complaint (n = 2), and reporting husband’s recent

death as the cause for insomnia complaints (n = 1)].

If the study criteria were fulfilled and there was no obvious

sleep-interfering circumstances causing the insomnia symp-

toms, the patient was offered a screening interview face-to-

face at our research group’s clinical setting. In sum, 36 par-

ticipants were screened at this stage. During the interview, the

Duke Structured Interview for Sleep Disorder (DSISD;

Edinger et al., unpublished material) and Structured Clinical

Interview for DSM-IV Axis I disorders (SCID-I; First,

Gibbon, Spitzer, & Williams, 1997) was administered by the

first, third, or sixth author. The DSISD assesses DSM-IV-TR

sleep disorders (i.e. insomnia, hypersomnia, circadian-

rhythm sleep disorder, and parasomnia) and associated psy-

chiatric and medical conditions, medications, drugs, sub-

stances, beverages, and allergies. The DSISD has showed

acceptable reliability and discriminant validity in studies

(Carney, Ulmer, Edinger, Krystal, & Knauss, 2009). If psy-

chiatric symptoms were reported, the SCID-I (SCID-I; First

et al., 1997) was used. In addition, the self-report instrument

SLEEP-50 (Spoormaker, Verbeek, van den Bout, & Klip,

2005), which establishes DSM-IV sleep disorder (apnea,

narcolepsy, restless legs/periodic limb movement disorder,

circadian rhythm disorder, insomnia, sleep state mispercep-

tion, sleep walking, nightmares, affective disorder, and

hypersomnia) was also filled out by the patient to check the

diagnostic reliability, indicating a complete agreement

between DSISD and SLEEP-50 diagnosis.

In addition to the above inclusion criteria, it was

required that the participant met the following criteria: (1)

DSM-IV-TR criteria for insomnia, and (2) insomnia not

better explained by another sleep disorder, psychiatric

condition, medical disease, or sleep-disturbing agents. The

following exclusion criteria were used: (1) evidence

of another sleep disorder (e.g. restless legs syndrome,

hypersomnia, or parasomnia), (2) evidence of a serious

psychiatric or medical condition, (3) evidence of a sleep-

disturbing agent causing insomnia, and (4) insufficient

skills in the Swedish language. If all the above criteria were

226 J Clin Psychol Med Settings (2012) 19:224–234

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met, the patient was offered participation in the project. If

the patient agreed to participate, he or she signed an

informed consent and the pre-treatment questionnaires

were filled out. In total, four individuals were excluded at

the interview stage [reporting restless legs syndrome as the

cause for the insomnia complaints (n = 2) and reporting

severe tinnitus distress as the cause for the insomnia

complaints (n = 2)].

A total of 32 individuals were included in the study. All

included participants signed a written consent and were then

randomized to either CBT-I or the WLC. A pure-tone

audiogram was collected for each participant to assess the

degree of hearing loss. Degree of hearing loss was calculated

using the criteria stated by the European Concerted Action

Project on Genetics of Hearing Impairment (HEAR) (1996).

According to these criteria, degree of hearing loss is divided

into four categories (average across 500, 1000, 2000 and

4000 Hz, i.e. pure-tone average PTA); Mild hearing loss

(over 20 dB HL and less than 40 dB HL), Moderate hearing

loss (over 40 dB HL and less than 70 dB HL), Severe

hearing loss (over 70 dB HL and less than 95 dB HL) and

Profound hearing loss (equal to and over 95 dB HL). Out-

come measures were administered at three time points

(pre-treatment, post-treatment, and 3-month follow-up) and

consisted of a questionnaire battery and a weekly sleep diary.

Pre-treatment measures were filled out just prior to starting

the assigned intervention. After that the intervention and

WLC were completed, post-treatment measures were filled

out (8 weeks after pre-treatment). 3 months after post-

treatment, follow-up measures were completed.

Randomization

A block randomization, executed by an independent

researcher and a table of random numbers, was used to

assign each participant to either the CBT-I condition or the

WLC. Randomization was executed for each block, con-

sisting of ten participants, and allocation of five partici-

pants to each group followed (each block of ten candidates

contained five CBT-I cells and five waitlist cells). Ran-

domization occurred after the pre-treatment assessment had

been completed. The table of random numbers was kept in

a locked drawer, which was only opened when a participant

had met the study criteria. The assignment was made by the

member of our research group who performed the inter-

view (the first, third or sixth author). 17 participants were

assigned to the CBT-I condition and 15 to the waitlist

control condition.

Procedure

At three time points (pre-treatment, post-treatment, and

3-month follow-up), the participants were sent the

questionnaires and a weekly sleep diary by mail. Along

with the questionnaires and the sleep diary, a letter of

introduction, information about the project, and a stamped

return-envelope were also included. Participants completed

the material at home and returned it in the envelope pro-

vided. If a response had not been received within 2 weeks,

a reminder was sent. If the questionnaire was not received

within an additional 2 weeks, a second reminder was sent.

Experimental Conditions

Cognitive Behavior Therapy for Insomnia (CBT-I)

Participants belonging to the CBT-I condition filled out the

pre-treatment assessment and were then randomized. After

the CBT-I condition, post-treatment and 3-month follow-

up assessment followed. The treatment was administered

by the first, third, and sixth author at our research group’s

clinical setting. The three therapists were trained psychol-

ogists and had previous experience in working with

insomnia patients. Homework and sleep diaries were used

throughout the entire CBT-I condition. Homework was

administered at the end of all the sessions and was fol-

lowed-up upon at the subsequent sessions. Problems with

homework assignments were addressed by the therapists,

and strategies for improving adherence were devised col-

laboratively with the participant.

To ensure treatment implementation, a model, which

highlights the need to monitor treatment delivery, receipt,

and enactment, was followed (Lichstein, Riedel, & Grieve,

1994). In short, delivery (integrity) was achieved by

(a) therapist training and supervision, (b) a detailed, ses-

sion-by-session treatment manual, (c) therapist documen-

tation of all the sessions in a journal for each patient, which

mirrored the steps in the manual, and (d) patient handouts

of all information and components that was provided orally

in the session. Receipt was attained by (a) asking the

patient at the end of each session to describe the treatment

components for that session and the therapist supplying

additional information if a component was not described in

a full manner and (b) documentation of the effects of in-

session component training (e.g. rate tension level before

and after relaxation training). Enactment was achieved by

(a) underscoring the importance of component implemen-

tation outside the clinical setting and (b) asking the patient

to document the use of all homework assignments and

using the registers at all sessions to identify and solve

encountered difficulties.

The participants received a seven-session (*1 h each),

weekly structured program administered on an individual

basis. The various components in the intervention were

introduced in an ordered manner and were followed-up

upon at the subsequent sessions. The first session was


123

devoted to sleep education, presenting a CBT format for

treating insomnia, individualizing sleep hygiene principles,

and relaxation training (short progressive muscle relaxa-

tion). The second session consisted of principles for and

individualization of sleep restriction and stimulus control.

The third session was devoted to solving problems with

regard to sleep restriction and stimulus control. The fourth

session consisted of education about how worry is related to

insomnia, principles for worry time, education about sleep

medications, and principles for gradual tapering (home-

work: diary assessment on the use of sleep medication). The

fifth session was devoted to problem solving and cognitive

restructuring of worry topics and to starting gradual taper-

ing of sleep medication (Morin, 1993). The sixth session

consisted of two components to address daytime impair-

ment: stress management techniques (relaxation, setting off

time for leisure, setting priorities, and saying no-skills) and

activity scheduling (increasing rewarding activities). The

seventh and final session was devoted to summarizing the

CBT-I intervention, relapse prevention, and constructing an

individualized CBT-I program for future purposes.

To investigate treatment expectancy and credibility of the

intervention, the participants in the CBT-I condition study

were administered the credibility/expectancy questionnaire

(CEQ; Devilly & Borkovec, 2000) at the first session fol-

lowing an explanation of the treatment rationale. On aver-

age, the 15 patients that underwent CBT-I (see Section

describing Dropout data for details about the reduction in

size of the CBT-I group) rated the treatment to be logical

(M = 7.9, SD = 0.74; score range: 1–9), with utility

(M = 7.8, SD = 1.3), had confidence in recommending the

treatment (M = 7.7, SD = 1.1), and felt that it would be of

help (M = 7.8, SD = 0.8). Further, the patients rated that

they thought that improvement would occur (M = 74,

SD = 11, score range: 0–100%) and also felt that improve-

ment would occur (M = 77, SD = 8; score range: 0–100%).

These credibility/expectancy data resemble to a high degree

results from an open trial on cognitive therapy for insomnia

(Harvey, Sharpley, Ree, Stinson, & Clark, 2007).

Waitlist Condition (WLC)

Participants belonging to the WLC initially filled out the

pre-treatment assessment and were then randomized. A

waiting period of 7 weeks occurred and then post-treat-

ment assessment followed. The participants were then

asked to fill out the 3-month follow-up assessment. Finally,

the participants were sent a self-help book in Swedish (234

pages), consisting of cognitive-behavioral components for

insomnia. Significant improvements have been docu-

mented for patients with insomnia reading and complying

with the instructions in this book (Jernelov et al., submitted

manuscript).

Self-Report Measures

The following instrument was employed as a primary outcome

measure: Insomnia Severity Index (ISI). The ISI is a stan-

dardized measure of sleep disturbance with established psy-

chometric properties (ISI; Bastien, Vallieres & Morin, 2001).

The ISI has standardized cut-offs: 0–7, no clinically signifi-

cant insomnia; 8–14, subthreshold insomnia; 15–21, moderate

clinical insomnia; and 22–28, severe clinical insomnia.

Secondary outcome measures were four sleep diary

outcomes and two questionnaires. Sleep diaries were

employed in combination with the ISI as a measure of sleep

disturbance. The diaries were filled out by the participants

during 1 week at three time-points (pre-treatment, post-

treatment, and follow-up). The diaries contained items

assessing the following domains: two items (sleep onset

latency and wake after sleep onset) tapping total wake time

(TWT in minutes), TST (TST in minutes), sleep restoration

(0–10; 0 = not at all restored, 10 = completely restored),

and sleep quality (0–10; 0 = very poor, 10 = very good).

The following two questionnaires with established psy-

chometric properties were also used as secondary mea-

sures: the Work and Social Adjustment Scale (WSAS) and

the Hospital Anxiety and Depression Scale (HADS). The

WSAS was used to assess daytime impairment (WSAS;

Mundt, Marks, Shear, & Greist, 2002). The WSAS assesses

functioning across work, home management, social leisure

activities, private leisure activities, and relationships with

others. The HADS was used to determine anxiety and

depression (HADS; Zigmond & Snaith, 1983).

Statistical Analysis

t Tests and v2 analyses were first used to examine whether

there were significant differences between the two groups at

pre-treatment on the baseline characteristics and outcome

measures. All the prospective analyses were based on the

intention-to-treat data. The missing data from the dropouts

were estimated by carrying forward the last valid observation

that was available for each outcome measure. On the primary

and secondary outcome measures, two-way repeated mea-

sures ANOVA were used. In these analyses, group assign-

ment (CBT-I and WLC) was treated as the between-subjects

factor and time (pre-treatment, post-treatment, and follow-

up assessment) was viewed as a repeated measure. Although

the main effects for group or time are also reported when

relevant, the Group 9 Time interaction was the main sta-

tistical contrast of interest. A significant Group 9 Time

interaction effect was followed by an examination of the time

effect within each group individually. A significant time

effect for either group was then followed by the appropriate

within-subject contrasts. Finally, between-groups compari-

sons were conducted on the post-treatment and follow-up


123

scores. To control Type I error, a family-wise procedure was

used to adjust the alpha level for the outcome measures. The

outcome measures were first classified into three categories:

insomnia severity (ISI), nighttime symptoms (TWT, TST,

sleep restoration, and sleep quality), and daytime symptoms

(WSAS, HADS-A, and HADS-D). The p-level was then

adjusted by dividing .05 with the number of ANOVA within

each outcome category. The p-level for significance was thus

.05 for insomnia severity, .0125 for nighttime symptoms, and

.0167 for daytime symptoms. The p-level for simple effects

was set at p = .025.

Within-group effect sizes (ES) were calculated [(pre-

treatment minus post-treatment or follow-up)/pooled stan-

dard deviation] to gain an impression of the magnitude of

improvement associated with treatment. Between-group ES

were also calculated [(post-treatment or follow-up for CBT-I

minus post-treatment or follow-up for WLC/pooled standard

deviation)]. Cohen (1988) proposed a threefold classification

of ES: small (.20–.49), medium (.50–.79) and large (.80 and

above). The outcome measure that was employed to examine

treatment response and remission resulting from the two

conditions was the ISI. v2 statistic was employed to explore

whether there were significant differences on response and

remission between the two conditions.

Results

Baseline Characteristics

The baseline characteristics for the two groups are reported

in Table 1. t Tests and v2 analyses were used to examine

whether there were differences between the two groups on

the baseline characteristics. The results showed that there

were no differences between the two groups on any of the

baseline characteristics (see Table 1). Approximately half

of the participants had mild hearing loss and the remaining

half moderate hearing loss. There were no statistical dif-

ferences between the groups regarding pure-tone average

and hearing loss category. The types of medications that

were self-reported by the sample were hypnotic medica-

tions. All the participants that reported medication use

described doses as recommended by their physicians and

on average a weekly medication use of 2.3 nights per week.

At post-treatment and follow-up, there was no change in

medication use, neither in the CBT-I group nor in the WLC

group. The three psychiatric disorders that were diagnosed

in the total sample were major depression, generalized

anxiety disorder, and specific phobia. The three most

common medical disorders that were self-reported were

chronic pain disorders, headaches, and gastrointestinal

disorders.

Dropout

Two participants dropped out during the study period. Both

the participants were randomized to CBT-I but dropped out

before starting the intervention due to practical reasons (i.e.

one patient was transferred by her employer to work in

another country and one underwent back surgery followed

by a lengthy rehabilitation). The two dropouts were

included in the intention-to-treat analyses. No other par-

ticipant dropped out during the study period, neither during

the intervention phase nor during the follow-up. In sum, the

Table 1 Overview of the study

participants

Means are presented with

standard deviations in

parenthesis

CBT-I (n = 17) WLC (n = 15) v2/t

Mean age (years) 57.8 (6.6) 53.6 (10.4) 1.39

Gender (female) 58.9% 66.6% 0.21

Civil status (cohabitant or married) 82.4% 80.0% 0.03

Occupational status (employed or student) 100% 93.3% 2.42

Education (college or university) 47.1% 60.0% 0.54

Type of sleep complaint

Sleep onset 5.9% 20.0% 3.47

Sleep maintenance 35.3% 46.7%

Mixed 58.8% 33.3%

Duration of insomnia (years) 11.5 (5.4) 8.8 (5.0) 1.44

Pure-tone average 39.2 (8.5) 33.1 (10.6) 1.82

Hearing loss

Mild 35.3% 66.7% 3.14

Moderate 64.7% 33.3%

Medication use 29.4% 33.3% 0.06

Psychiatric co-morbidity 23.5% 33.3% 0.38

Medical co-morbidity 64.7% 40.0% 1.95


123

total dropout rate was 6%. Due to the small number of

dropouts, it was not possible to determine with inferential

statistics whether the dropouts differed from the complet-

ers. Instead, only visual analysis was performed on clinical

parameters. The visual analysis indicated that the two

dropouts, in comparison with the completers, had lower ISI

(12.5 vs. 18.7), shorter SOL (24 vs. 43 min), shorter

WASO (40 vs. 75 min), longer TST (402 vs. 345 min), and

higher sleep quality (6.7 vs. 4.3). In sum, the dropouts

appeared to be characterized by less severe insomnia

complaints than the completers.

Primary Outcome Measure

The data across the two groups for the primary outcome

measure, the ISI, are displayed in Table 2. A t test was first

used to examine whether there were differences between

the two groups on the primary outcome measures at

baseline. The results showed that there was no significant

difference between the two groups at baseline on the ISI

(t = -.76, p = .45). The 2 9 3 ANOVA of ISI revealed a

significant Group 9 Time interaction [F(2, 29) = 8.18,

p = .002], which reflected a reliable reduction over time

Table 2 The effects of the interventions on the primary and secondary outcome measures

CBT-I WLC

M SD Within ES M SD Within ES Between ES

Insomnia severity (0–28; ISI)

Baseline 17.6 4.0 19.0 5.7

Post-treatment 10.5 4.4 -1.70 18.1 5.3 -.17 1.56

3-month follow-up 11.3 6.8 -1.18 18.2 4. -.15 1.18

TWT (min)

Baseline 117.7 45.2 111.4 50.1

Post-treatment 48.2 20.5 -2.11 102.6 58.1 -.16 1.39

3-month follow-up 54.0 14.6 -2.13 103.8 56.9 -.14 1.39

TST (min)

Baseline 343.9 85.7 361.7 55.8

Post-treatment 385.3 22.7 .76 383.7 60.7 .38 .04

3-month follow-up 378.6 31.3 .59 372.8 52.9 .20 .14

Sleep restoration (0–10)

Baseline 4.3 1.6 4.1 1.8

Post-treatment 6.2 1.3 1.35 4.1 2.0 .02 1.07

3-month follow-up 5.4 1.3 1.32 4.2 2.0 .07 1.03

Sleep quality (0–10)

Baseline 4.3 1.3 4.7 1.9

Post-treatment 6.5 1.5 1.58 5.1 1.5 .24 .91

3-month follow-up 6.3 0.8 1.92 5.0 1.3 .24 1.16

Dysfunction (0–40; WSAS)

Baseline 20.5 6.6 21.1 12.2

Post-treatment 12.1 8.6 -1.10 18.4 8.8 -.24 .81

3-month follow-up 10.8 9.2 -1.22 19.4 9.7 -.17 .96

Anxiety (0–21; HADS)

Baseline 6.5 2.1 7.9 3.4

Post-treatment 5.1 2.5 -.62 9.2 3.8 .35 1.29

3-month follow-up 5.5 1.7 -.56 8.8 3.4 .26 1.30

Depression (0–21; HADS)

Baseline 6.6 2.9 7.6 4.0

Post-treatment 4.3 2.8 -.70 7.5 3.9 -.02 1.00

3-month follow-up 4.3 2.6 -.74 7.9 3.6 .09 1.22

CBT cognitive behavior therapy, ES effect size, HADS Hospital Anxiety and Depression Scale, ISI Insomnia Severity Index, WLC waitlist

condition, WSAS Work and Social Adjustment Scale


123

for the CBT-I group (F = 17.30, p \ .001), but not for the

WLC group (F = 0.39, p = .68). The ISI score for the

CBT-I group was significantly reduced from pre-treatment

to post-treatment [t(16) = 8.01, p \ .001] and from pre-

treatment to follow-up [t(16) = 4.38, p \ .001]. Between-

groups contrasts confirmed that the CBT-I group had a

lower ISI score than did WLC participants at both post-

treatment [t(30) = -4.40, p \ .001] and follow-up

[t(30) = -3.26, p = .003]. As is displayed in Table 2, the

ES for the CBT-I group on ISI were large, small for the

WLC group, and the between-group ES were large.

Secondary Outcome Measures

The data for the secondary outcome measures are displayed

in Table 2. t Tests were employed to explore whether there

were differences between the two groups on the secondary

outcome measures at baseline. The results showed that

there were no significant differences between the two

groups at baseline on the measures [TWT: t = .38,

p = .71; TST: t = -.70, p = .49; sleep restoration: t =

-.08, p = .94; sleep quality: t = -.69, p = .50; dys-

function: t = -.17, p = .87; anxiety: t = -1.44, p = .16;

depression: t = -1.06, p = .30)].

The 2 9 3 ANOVA of TWT revealed a significant

Group 9 Time interaction [F(2, 29) = 12.88, p = .001],

which reflected a reliable reduction over time for the CBT-I

group (F = 28.73, p \ .001), but not for the WLC group

(F = 0.67, p = .52). For the CBT-I group, TWT was

significantly reduced from pre-treatment to post-treatment

[t(16) = 5.76, p \ .001] and from pre-treatment to follow-

up [t(16) = 5.82, p \ .001]. Between-groups contrasts

confirmed that the CBT-I group had lower TWT than did

WLC participants at both post-treatment [t(30) = -3.62,

p = .001] and follow-up [t(30) = -3.48, p = .005]. As is

shown in Table 2, the ES for the CBT-I group on TWT

were large, negligible for the WLC group, and the

between-group ES were large.

The 2 9 3 ANOVA of TST did not reveal a significant

Group 9 Time interaction [F(2, 29) = 1.04, p = .34].

However, a significant main effect of time was noted [F(2,

29) = 7.04, p = .006]. Across both the CBT-I and WLC

participants, TST was increased from pre-treatment to post-

treatment [t(31) = -3.26, p = .003] and from pre-treat-

ment to follow-up [t(31) = -2.28, p = .029]. As is shown

in Table 2, the ES for the CBT-I group on TST were

medium, small for the WLC group, and the between-group

ES were small.

The 2 9 3 ANOVA of sleep restoration revealed a




WLC group (F = 0.09, p = .92). For the CBT-I group,

sleep restoration was significantly increased from pre-

treatment to post-treatment [t(16) = -4.76, p \ .001]

and from pre-treatment to follow-up [t(16) = -5.34,

p \ .001]. Between-groups contrasts confirmed that the

CBT-I group had higher sleep restoration than the WLC

group at both post-treatment [t(30) = 2.96, p = .009] and

follow-up [t(30) = 2.90, p = .007]. As is displayed in

Table 2, the ES for the CBT-I group on sleep restoration

were large, negligible for the WLC group, and the

between-group ES were large.

The 2 9 3 ANOVA of sleep quality revealed a signifi-

cant Group 9 Time interaction [F(2, 29) = 5.76,




sleep quality was significantly increased from pre-treat-

ment to post-treatment [t(16) = -5.63, p \ .001] and from

pre-treatment to follow-up [t(16) =-6.70, p \ .001].

Between-groups contrasts confirmed that the CBT-I group

had higher sleep quality than the WLC group at both post-

treatment [t(30) = 2.58, p = .015] and follow-up

[t(30) = 3.26, p = .003]. As is shown in Table 2, the ES

for the CBT-I group on sleep quality were large, small for

the WLC group, and the between-group ES were large.

The 2 9 3 ANOVA of dysfunction (WSAS) revealed a





function was significantly increased from pre-treatment to

post-treatment [t(16) = 6.02, p \ .001] and from pre-

treatment to follow-up [t(16) = 4.72, p \ .001]. Between-

groups contrasts confirmed that the CBT-I group had

higher function than the WLC group at both post-treatment

[t(30) = -2.28, p = .030] and follow-up [t(30) = -2.73,

p = .011]. As is displayed in Table 2, the ES for the CBT-I

group on WSAS were large, small for the WLC group, and

the between-group ES were large.

The 2 9 3 ANOVA of anxiety (HADS-A) showed a

significant Group 9 Time interaction (F(2, 29) = 5.48,

p = .007). The Group 9 Time interaction of depression

(HADS-D) was not significant [F(2, 29) = 2.71,

p = .075]. The main effects of time for anxiety [F(2,

29) = 0.29, p = .97] and depression [F(2, 29) = 2.15,

p = .13] were not significant. On anxiety, there was a

reliable reduction for the CBT-I group (F = 5.04,

p = .013) but not for the WLC group (F = 1.63,

p = .214). For the CBT-I group, anxiety was significantly

reduced from pre-treatment to post-treatment [t(16) =

3.87, p = .001] and from pre-treatment to follow-up

[t(16) = 2.50, p = .024]. Between-groups contrasts con-

firmed that the CBT-I group had lower anxiety than the

WLC group at both post-treatment [t(30) = -3.63,


123

p = .001] and follow-up [t(30) = -3.55, p = .003]. As is

shown in Table 2, the effect size for the CBT-I group on

anxiety were medium and on depression medium, small for

the WLC group on anxiety and negligible on depression, and

the between-group ES on anxiety and depression were large.

The findings on the secondary outcome measures thus

show that CBT-I over time, relative to WLC, resulted in a

larger reduction on TWT, a larger increase on sleep res-

toration and sleep quality, and a larger decrease on dys-

function and anxiety. Though both CBT-I and WLC led to

increases in TST, no significant group difference emerged.

Neither CBT-I nor WLC resulted in significant changes on

depression.

Treatment Response and Remission

Aside from showing that interventions produce statistically

significant improvements, it is also important to demon-

strate that these changes are clinically meaningful. To

examine treatment response and remission, the primary

outcome measure was used. The results are displayed in

Table 3. Treatment response on the ISI was defined as an

ISI change score, from baseline to post-treatment or fol-

low-up, equivalent to one category on the ISI (7 points)

(Morin et al., 2009). A significantly larger number of

participants in the CBT-I group showed treatment response

according to the ISI compared to the control group at both

post-treatment (v2 = 15.78, p \ .001) and follow-up

(v2 = 11.05, p = .001). Treatment remission on the ISI

was defined as an ISI score less than 8 points at post-

treatment or follow-up (Morin et al., 2009). A significantly

larger number of participants in the CBT-I group remitted

according to the ISI compared to the control group at post-

treatment (v2 = 4.03, p = .045) but not at follow-up

(v2 = 2.92, p = .087).

Discussion

The current study indicates that, relative to a WLC, CBT

for insomnia co-morbid with hearing impairment was

effective in reducing insomnia severity, subjective sleep

parameters, dysfunction, and anxiety. Cognitive behavioral

therapy also resulted in a relatively high rate of treatment

responders and one-fourth of the CBT-I participants ful-

filled criteria for insomnia remission.

Concerning the primary outcome, the ISI, CBT-I resul-

ted in superior results at both post-treatment and follow-up.

While the percentage decrease for CBT-I was 36–40%, the

WLC showed only a small improvement on the ISI over the

study period (4–5%). The superiority of CBT-I over WLC

was also confirmed by the large controlled ES.

Regarding the secondary nighttime outcomes, relative to

the WLC condition, the CBT-I condition showed superior

outcomes on TWT, sleep restoration, and sleep quality. The

controlled ES were large for all the secondary nighttime

outcomes, in favor for CBT-I. While both groups increased

their TST (increase of 10–12% in CBT-I and 3–6% in

WLC), no significant group difference was noted. The

CBT-I group showed a marked improvement over time;

percentage change was 54–59% for TWT, 26–44% for

sleep restoration, and 47–51% for sleep quality. These

findings contrast widely with the WLC group; percentage

change was 7–8% for TWT, 0–2% for sleep restoration,

and 6–9% for sleep quality. In all, the WLC showed only a

small improvement on secondary sleep outcomes. Though

the ES were small for the WLC in this study on the sleep

outcomes, they are in line with a meta-analysis in which

the effects on sleep parameters are demonstrated to be very

small to small for WLC (Belanger et al., 2007). Concerning

the secondary daytime outcomes, compared with the WLC

group, the CBT-I group showed a superior outcome on

dysfunction and anxiety. While CBT-I resulted in a

41–47% decrease on dysfunction and 15–22% reduction on

anxiety, the WLC group showed a smaller improvement on

dysfunction (8–13% decrease on dysfunction) and a

worsening on anxiety (11–16% increase). The controlled

ES was large for dysfunction and anxiety, in favor for

CBT-I. No significant group difference emerged for

depression. While CBT-I resulted in a 35% reduction in

depression, WLC led to a general worsening of depression

(1% decrease to 4% increase).

Table 3 Treatment response and remission based on the ISI

CBT-I WLC

n (%) N (%)

Response: post-treatmenta 13 76.5 1 6.7

Response: follow-upa 9 52.9 0 0

Remission: post-treatmentb 4 23.5 0 0

Remission: follow-upb 3 17.6 0 0

a ISI change score, from baseline to post-treatment or follow-up, equivalent to one category on the ISI (7 points)b ISI score less than 8 points at post-treatment or follow-up


123

In terms of treatment response and remission, CBT-I

resulted in a superior result over the WLC. The response

rate was significantly higher for CBT-I on the ISI at both

assessment points. The remission rate was also signifi-

cantly higher for CBT-I on the ISI at post-treatment. The

response and remission rates for CBT-I in this study can be

compared with a recent study employing the same criteria

for response and criteria (Morin et al., 2009). While the

response rate in the current investigation was slightly

higher (52.9–76.5%) than a previous study using CBT for

insomnia (59.5%), the remission rate was smaller (23.5 vs.

39.2%). Conclusively, although three out of four patients

showed clear improvement in this study, only one-fourth

demonstrated remission.

Given the co-morbid nature of the current sample, a few

comments regarding comparability with other, mainly

primary insomnia patients, on pre-treatment characteristics

are warranted. Based on the ISI, the current sample appears

to resemble other insomnia patients (Morin et al., 2009:

M = 17.3–17.6; current sample: M = 17.6–19.0). Except

for a slightly longer TST in the current sample, there is also

a relatively high comparability when sleep diary parame-

ters (Okajima, Komada, & Inoue, 2011) and dysfunction

(Harvey et al., 2007) are considered. Based on anxiety and

depression scores, there is also a relatively high compara-

bility (Morgan, Dixon, Mathers, Thompson, & Tomeny,

2003). Conclusively, our sample consisting of participants

with both insomnia and hearing impairment resemble other

insomnia patients to a high degree.

Although CBT-I needs to be tested more in future

research, the current findings indicate that there may be

clinical benefits for patients with insomnia co-morbid with

hearing impairment. While this study consisted of both

effectiveness (e.g. patients recruited in clinical settings)

and efficacy (e.g. patients treated outside the clinical set-

ting) trial elements, future studies might investigate the use

of CBT-I in audiology clinics using regular health care

staff delivering the intervention, thereby moving towards

effectiveness. To further validate the effects of CBT-I,

objective sleep measures, e.g. actigraph, might also be

added. We also highlight the need for using alternate

control groups, e.g. treatment-as-usual, in future trials.

A number of methodological limitations should be men-

tioned. First, a WLC as a control element does not adequately

control for non-specific therapeutic factors or demand

characteristics. A more potent design, a placebo control or

treatment-as-usual, is therefore recommended in future

research. Second, the exclusion of patients with severe tin-

nitus distress limits the generalizability to those with mild or

moderate tinnitus distress. Third, although patients were

mainly recruited in the usual care system, they were assessed

and treated at a university setting, possibly limiting the

generalizability. Fourth, polysomnographic recordings were

not used during screening, thereby opening up the possibility

that patients with other sleep disorders (e.g. sleep apnea)

were included in the sample. However, we would like to note

that we used a validated diagnostic interview as well as a

sleep screening instrument to rule out sleep disorders other

than insomnia. Fifth, no objective sleep assessment was

made, limiting the conclusions to the patients’ report of

complaint. However, we note that both the DSM-IV system

as well as research diagnostic criteria for insomnia (Edinger

et al., 2004) underscore that insomnia is a subjective com-

plaint, and self-report assessment is therefore critical. Sixth,

the length of the follow-up was limited to 3 months, and

information about efficacy over the longer term is lacking.

Finally, no outcomes related to hearing impairment were

used in the study, limiting the conclusions only to insomnia-

related outcomes.

In summary, the current investigation showed that CBT

for insomnia was effective in reducing insomnia symp-

tomatology and associated correlates in patients with

insomnia co-morbid with hearing impairment. This is a

promising finding since sleep complaints are common

among individuals with hearing impairment. Based on the

current and previous findings, it is also plausible to ques-

tion the traditional notion that insomnia will not respond to

treatment unless the associated condition is treated first.

The current results add and extend previous findings

showing that CBT-I is effective also for secondary and co-

morbid insomnia.

Acknowledgment We would like to express our appreciation to

Sparbankstiftelsen Nya for funding and to the two audiology clinics in

Orebro and Karlstad for recruitment.

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Cognitive-Behavioral Therapy for Insomnia Co-Morbid with Hearing Impairment: A Randomized Controlled Trial