Expanding Self-Help Imagery Rehearsal Therapy for Nightmares With Sleep Hygiene and Lucid Dreaming: A Waiting-List Controlled Trial

Abstract

Nightmares are a common disorder with serious consequences. Recently, the cognitive behavioral interventions Imagery Rehearsal Therapy (IRT) and exposure proved effective in a self-help format. The aim of the current study was to compare the following self-help formats to a waiting-list: IRT; IRT with sleep hygiene; and IRT with sleep hygiene and a lucid dreaming section. Two-hundred-seventy-eight participants were included and randomized into a condition. Follow-up measurements were 4, 16, and 42 weeks after baseline. Seventy-three participants filled out all questionnaires and 49 returned the nightmare diaries. Contrary to our expectations, the original IRT was more effective than the two other intervention conditions. Moreover, IRT was the only intervention that convincingly proved itself compared to the waiting-list condition. However, these data should be interpreted with caution due to the low power and high dropout. Yet it seems that in a self-help format, IRT and exposure (which was validated previously) are the treatments of choice for treating nightmares.

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Expanding IRT Self-Help for Nightmares
1. Introduction
Nightmares are a common disorder affecting 2-5% of the
general population (Bixler, Kales, Soldatos, Kales & Healey,
1979; Li, Zhang, Li & Wing, 2010; Schredl, 2010; Spoor-
maker & van den Bout, 2005). The DSM-IV-TR denition of
nightmares is: “extremely frightening dreams that lead to
awakening” (American Psychiatric Association., 2000), al-
though various emotions have been reported in nightmares
(Zadra, Pilon & Donderi, 2006) and direct awakening seems
not to be associated with increased distress (Blagrove,
Farmer & Williams, 2004).
Nightmares have serious nighttime consequences by dis-
turbing the sleep (Kales et al., 1980) and also inict daytime
distress (Berquier & Ashton, 1992; Zadra & Donderi, 2000).
Nightmares can be part of posttraumatic stress disorder
(PTSD; Wittmann, Schredl & Kramer, 2007) and are associ-
ated with higher psychopathology scores (Hublin, Kaprio,
Partinen & Koskenvuo, 1999; Levin & Fireman, 2002; Zadra
& Donderi, 2000). However, it seems that nightmare distress
rather than nightmare frequency is related to these psy-
chopathology scores (Blagrove et al., 2004; Schredl, 2003).
Moreover, a recent study found that nightmare frequency
appears to be related to sleep complaints instead of mental
complaints (Lancee, Spoormaker & van den Bout, 2010b).
These ndings suggest that nightmares are best conceptu-
alized as a sleep disorder that should receive specic diag-
nosis and treatment.
Nightmares can be adequately treated with cognitive-
behavioral therapy (CBT; Spoormaker, Schredl & van den
Bout, 2006; Wittmann et al., 2007). Imagery rehearsal ther-
apy (IRT) and exposure are the two most thoroughly em-
pirically tested treatments for nightmares (e.g. Burgess, Gill
& Marks, 1998; Krakow, Kellner, Pathak & Lambert, 1995).
In both treatments the nightmares are imagined during the
day. In exposure, desensitization occurs by imagining the
original nightmare; IRT employs exposure as well but the
nightmare is imagined in a changed format.
Nightmare sufferers rarely receive treatment, probably
because of the unavailability of trained cognitive-behavior
therapists. Self-help treatment might provide a solution for
the low accessibility of effective treatment. Recently we
found IRT and exposure to be equally effective in a self-help
format in ameliorating nightmares compared to a waiting-
list and recording control group (Lancee, Spoormaker & van
den Bout, 2010a); effects of IRT and exposure were sus-
tained 42 weeks after the intervention (Lancee, Spoormak-
er & van den Bout, in press), but only 15-20% was totally
nightmare free at this 42-week follow-up.
Expanding the self-help format with techniques such as
lucid dreaming therapy (LDT) might further enhance treat-
ment effectiveness. Lucid dreaming is a technique where-
by the dreamer is aware that he/she is dreaming (Hobson,
2009; LaBerge & Rheingold, 1990). Lucid dreaming has
been physiologically veried by volitional eye movements
on the electrooculogram during rapid eye movement (REM)
sleep (e.g., LaBerge, Nagel, Dement & Zarcone, 1981). Lucid
dreaming frequency is moderately correlated with nightmare
Expanding Self-Help Imagery Rehearsal Therapy
for Nightmares with Sleep Hygiene and Lucid
Dreaming: A Waiting-List Controlled Trial
Jaap Lancee, Jan van den Bout, & Victor I. Spoormaker*
Utrecht University, Department of Clinical and Health Psychology, Utrecht, the Netherlands
*Present afliation: Max Planck Institute of Psychiatry, Munich, Germany
Corresponding address:
Jaap Lancee, MSc., Utrecht University, Department of Clinical
and Health Psychology, PO Box 80.140, 3508TC Utrecht,
the Netherlands; Tel: +31 30 253 2387; Fax: +31 30 253
4718; E-mail: j.lancee@uu.nl
Submitted for publication: August 2010
Accepted for publication: October 2010
Summary. Nightmares are a common disorder with serious consequences. Recently, the cognitive behavioral interven-
tions Imagery Rehearsal Therapy (IRT) and exposure proved effective in a self-help format. The aim of the current study
was to compare the following self-help formats to a waiting-list: IRT; IRT with sleep hygiene; and IRT with sleep hygiene
and a lucid dreaming section. Two-hundred-seventy-eight participants were included and randomized into a condition.
Follow-up measurements were 4, 16, and 42 weeks after treatment completion. Seventy-three participants completed
all questionnaires and 49 returned the nightmare diaries. Contrary to our expectations, the original IRT was more effec-
tive than the two other intervention conditions. Moreover, IRT was the only intervention that convincingly proved itself
compared to the waiting-list condition. However, these data should be interpreted with caution due to the low power and
high dropout. Yet it seems that in a self-help format, IRT and exposure (which was validated previously) are the treat-
ments of choice for nightmares.
Keywords: Nightmares; Self-Help; Imagery Rehearsal; Lucid Dreaming

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frequency (Schredl & Erlacher, 2004), and it seems plausible
that nightmares can trigger lucid dreaming (Schredl & Er-
lacher, 2004). In LDT for nightmares participants imagine
their (changed) nightmare during the day while thinking that
they are only dreaming (thereby triggering lucidity in the real
nightmare). Because LDT targets the nightmare within the
dream it might be specically benecial for people that suf-
fer from non-recurrent nightmares.
A few case studies (Spoormaker, van den Bout & Meijer,
2003; Zadra & Pihl, 1997) and one randomized controlled
study (Spoormaker & van den Bout, 2006) have studied
LDT; all indicated that LDT was effective. In the controlled
study, LDT was superior to a waiting-list on nightmare fre-
quency but did not have an effect on secondary measures
such as subjective sleep quality and PTSD complaints. LDT
and IRT have a similar treatment structure which makes it
possible to employ LDT as and ‘add on’ to IRT.
Moreover, nightmares and sleep quality have an in-
verse relationship (Ohayon, Morselli & Guilleminault, 1997;
Schredl, 2003; Schredl, 2009). It is possible that nightmares
have a direct effect on sleep (i.e. disrupting sleep patterns)
or an indirect effect on sleep by inducing fear of going (back)
to sleep. Some previous (uncontrolled) studies have used a
combined approach of nightmare and insomnia treatment
with promising results (e.g. Krakow et al., 2001; Swanson,
Favorite, Horin & Arnedt, 2009). A section that specically
focuses on improving dysfunctional sleeping habits (sleep
hygiene) could also be successful in a self-help format
and have a benecial effect as add-on to standard CBT for
nightmares.
The aim of the current study was to compare the following
self-help formats to a waiting-list: IRT; IRT with sleep hy-
giene (IRT+); and IRT with sleep hygiene and a LDT section
(LDT). Expectations were:
▪All treatment conditions have a benecial effect
compared to the waiting-list condition
▪IRT+ ameliorates sleep quality compared to IRT
▪LDT ameliorates nightmare frequency measures and
nightmare distress compared to IRT and IRT+
2. Method
2.1. Participants
Participants were recruited from October 2007 to April 2009
through a Dutch nightmare website (www.nachtmerries.
org). The Netherlands has the highest internet penetration
of Europe with 88% of the Dutch households connected to
the Internet in 2008 (Statistics Netherlands, 2009). Inclusion
criteria were: being eighteen years or older and having self-
reported nightmares based on the SLEEP-50 (Spoormaker,
Verbeek, van den Bout & Klip, 2005). Three-hundred-ninety-
eight participants started the online questionnaire which
279 (70.1%) completed. Exclusion criteria were: high score
on posttraumatic complaints (score > 53 on Dutch trans-
lation of the Impact of Event Scale - IES; Brom & Kleber,
1985), currently in treatment for PTSD, suicidal ideation, and
schizophrenia. See Table 1 for demographic characteristics
and see Figure 1 for owchart and exclusion rates of par-
ticipants’.
Of the 213 nightmare diaries sent out, only 49 (23.0%)
were returned: 16 (23.9%) in the IRT, 16 (21.3%) in the IRT+,
and 17 (23.9%) in the LDT condition. Return rates for the
diaries were low but comparable with our previous self-help
intervention study (Lancee et al., 2010a); this is probably be-
cause nightmare sufferers are reluctant to keep a log (Nei-
dhardt, Krakow, Kellner & Pathak, 1992).
Table 1. Demographic Characteristics of Participants per Condition.
Condition
IRT
(n = 67)
IRT+
(n = 75)
LDT
(n = 71)
WL
(n = 62)
Test p =
Mean age (SD) 33.4 (12.93) 38.9 (18.0) 36.5 (14.4) 35.5 (14.9) F(3, 274) = 1.59 .19
Sleep duration (SD) 7.1 (1.30) 7.5 (1.55) 7.14 (1.40) 7.05 (1.40) F(3, 274) = 1.23 .30
n%n%n%n%
Gender Male 10 5.9 21 28.0 17 23.9 15 24.2
χ2(3) = 3.62 .31
Female 57 5.1 54 72.0 54 76.1 47 75.8
Medication* Yes 13 9.4 23 30.7 11 15.5 15 24.2
χ2 (3) = 5.33 .15
No 54 0.6 52 69.3 60 84.5 47 75.8
In psychological
Treatment
Yes 12 7.9 15 20.0 15 21.1 3 4.8 χ2 (3) = 8.04 <.05
No 55 2.1 60 80.0 56 78.9 59 95.2
Self reported
Trauma
Yes 46 8.7 51 68.0 53 74.6 39 62.9 χ2 (3) = 2.16 .54
No 21 1.3 24 32.0 18 25.4 23 37.1
Note. * Mostly Selective Serotonin Reuptake Inhibitors - SSRI’s ( > 90%)

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Expanding IRT Self-Help for Nightmares
2.2. Procedure
The study was approved by the Medical Ethical Committee
of the University Medical Center Utrecht. Participants could
enter the baseline questionnaire after informed consent was
given. Participants were subsequently randomized to one of
four conditions: IRT (n = 70); IRT with sleep hygiene (IRT+;
n = 76); IRT with sleep hygiene and lucid dreaming (LDT;
n = 71); waiting-list (n = 62). Randomization was achieved
by a computerized random number generator creating a
random number table. Participants and project leader were
not blind to the assigned condition. For the sample size we
wanted to achieve similar power as in our former self-help
study (Lancee et al., 2010a). This sample size was based
on the fact that n = 51 is needed for adequate power (> 0.8)
to detect signicance at an effect size of d = 0.5. With a
dropout of around 50% this meant that groups of around n
= 100 were needed for each condition. However, due to low
recruitment rates we could include fewer participants and a
relatively high percentage dropped out. At 4-week follow-
up, we now had a sample size large enough to nd an effect
size of 0.6 – 0.7 with an alpha of .05 and adequate power
(> 0.8).
The six week intervention and diary were sent to the inter-
vention conditions directly after baseline questionnaires. The
waiting-list condition only received a letter that the post-test
would be in eleven weeks. Eleven weeks after completion
of the baseline (four weeks after intervention plus one ex-
tra week due to mailing time), participants in all conditions
lled out the online post-test questionnaire. If the post-test
was not completed, participants received two reminders
by e-mail, and one by regular mail. After completion of the
post-test participants in the waiting-list condition were sent
an intervention to fulll ethical obligations. No data are thus
available of the long-term effects of the waiting-list. Sixteen
and 42 weeks after the intervention participants lled out
post-test 2 and 3. The diary was returned directly after n-
ishing the intervention.
2.3. Measures
Nightmare frequency, nightmare distress, and subjective
sleep quality were measured by the 50-item SLEEP-50
(Spoormaker et al., 2005), a sleep questionnaire with
good reliability (α = 0.85, test-retest reliability 0.78). Com-
pared with polysomnographic and clinical diagnoses, the
SLEEP-50 shows good predictive validity for various sleep
disorders. In addition, the SLEEP-50 addresses the night-
mare frequency for the past week, the amount of nights
with nightmares a month, and the subjective sleep quality (1
‘very bad’ – 10 ‘very good’). For nightmares, the sensitivity
was 0.84 and the specicity was 0.77 compared to clinical
diagnosis. Moreover, six items (range 6 – 24) of the sleep
impact subscale were used for a nightmare distress scale
targeting the last seven days. In our study the sleep impact
subscale was preceded by: ‘Because of my nightmares…’
(e.g., I am told that I am easily irritated’).
Anxiety was measured by the Dutch version of the 20 item
Spielberger Trait Anxiety Inventory (Van der Ploeg, 1980).
The Trait Anxiety Inventory consists of twenty statements
about how much anxiety is generally experienced (e.g. I feel
content; 1 = almost never; 4 = almost always; range: 20 -
80). Reliability is good (α, range 0.87 - 0.96; test-retest cor-
relation is 0.84 - 0.88), and so is the validity (Van der Ploeg,
1980).
Depression was measured by a Dutch translation of the
20 item Centre of Epidemiological Studies-Depression scale
(CES-D; Bouma, Ranchor, Sanderman & van Sonderen,
1995). The CES-D scale consists of 20 items. This scale
(range 0 – 60) has good internal consistency (α, range 0.79
- 0.92; test-retest correlation is 0.90), and the validity of the
Dutch scale is promising compared to Beck Depression In-
ventory (e.g. correlation of 0.56 - 0.66; Bouma et al., 1995).
The CES-D uses a cut-off score of 16 to indicate mild de-
pression and 27 to indicate major depression disorder (Zich,
Attkisson & Greeneld, 1990).
Posttraumatic stress complaints were measured by a
Dutch translation of the 15 item IES (Brom & Kleber, 1985).
Only participants who had experienced a trauma lled out
the questionnaire (n =; 189; range 0 - 75). Cut-off scores
to indicate PTSD is 26 in the Dutch version. This scale has
good internal consistency (α range: 0.87 - 0.96), and con-
struct validity comparable with the original IES (van der
Ploeg, Mooren, van der Velden, Kleber & Brom, 2004).
2.4. Diary
The nightmare diary was kept on a daily basis by all three
intervention conditions for a six-week period. Participants
lled out each day: quality of sleep (0 ‘very poor’ – 7 ‘very
good’); amount of nightmares; and intensity of nightmare (1
‘not intense’ – 7 ‘very intense’).
Table 2. Overview Self-Help Intervention.
Imagery
Rehearsal Therapy (IRT)
IRT and
sleep hygiene (IRT+)
IRT+ and
Lucid Dreaming Therapy (LDT)
▪Recording
▪Writing down nightmares
▪Thinking about cognitive origin
nightmare
▪Imaginative relaxation
▪Progressive muscle relaxation
▪Change ending nightmare
▪Imagining changed ending of
nightmare (10-15 minutes a day)
▪Troubleshooting
IRT and
If sleep quality is bad: Go to bed only
when sleepy, use the bed and bed-
room for sleep only, maintain a reg-
ular rising time, get out of bed and
into another room when unable to
fall asleep.
IRT and
Sleep hygiene and
Imagining nightmares during the day
while thinking that it is only a dream
- thereby triggering lucidity during
the nightmare

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2.5. Intervention
For this study the self-help IRT booklet of Lancee et al.
(2010a) was used (approximately 5800 words). IRT consists
of exposure to nightmare imagery and instructs participants
to imagine an altered version of the nightmare (Krakow &
Zadra, 2006). The IRT book was expanded for the IRT+
condition with a sleep hygiene section of approximately
800 words employing sleep hygiene and stimulus control.
In this section participants were instructed to go to bed only
when sleepy, use the bed and bedroom for sleep only, main-
tain a regular rising time, avoid daytime naps and get out
of bed and into another room when unable to fall asleep.
Participants were told to improve their bedroom for sleeping
by optimizing external factors like mattress softness, tem-
perature, and light. Moreover, participants received specic
instructions for what to do if a nightmare would occur; par-
ticipants for instance received the suggestion to perform
a muscle relaxation exercise and/or imagination of a safe
place. In the LDT condition the IRT+ version (that also in-
cluded the sleep hygiene section) was used with an extra
lucid dreaming section (approximately 900 words). Partici-
pants in the LDT condition rst received IRT instructions to
think about the cognitive origin of the dream, change the
nightmare ending, and imagine the changed nightmare. The
participants then received additional instructions to imagine
the changed nightmare while thinking that it is only a dream
(‘this is not real, but this is only a dream’). Moreover, partici-
pants received instructions to imagine during the day how
they would change their nightmare while dreaming (see Ta-
ble 2). Subjects in all three intervention conditions received
a diary as part of their treatment.
2.6. Statistical analysis
An intention-to-treat (ITT) multilevel regression analysis was
conducted to evaluate the success of the different interven-
tions (Hox, 2002). Multilevel regression is an ITT procedure
which allows participants with only one measurement to be
included in the analyses (Hox, 2002). At baseline, fewer par-
ticipants in the waiting-list condition were ‘in psychological
treatment’ than in the other conditions (p < .05). Dropout
was analyzed with logistic regression analyses. Attrition
could have inuenced post-test scores and therefore Co-
hens’ d estimations. To correct for this problem multiple
imputation based on the ‘missing at random assumption’
was employed (Sterne et al., 2009). For the missing scores,
ten separate datasets were generated with predictive mean
matching. Changes in Cohen’s d’s were calculated with
((Mpre1 – Mpost1) – (Mpre2 – Mpost2)) / σpooled-pre-test (Morris, 2008).
Figure 1. Flowchart and exclusion rates of participants’.
IRT n = 70
278 participants
enrolled
(finished baseline)
Assessed for eligibility 398
120 did not complete baseline, because:
- Did not finish n = 38
- High PTSD complaints n = 47
- In treatment for PTSD n = 22
- Nightmares/week < 1 n = 5
- Psychosis / Schizophrenia n = 7
- Suicidal ideation n = 1
n = 47
n = 50
n = 40
Analysed n = 67
Outliers n = 3*
IRT+ n = 76
n = 34
n = 54
n = 57
LDT n = 70
n = 46
n = 47
n = 37
Analysed n = 75
Outliers n = 1*
Analysed n = 71
Outliers n = 0
WL n = 62
n = 16
Analysed n = 62
Outliers n = 0
Lost to
post-1
Lost to
post-2
Lost to
post-3
Figure 1 – Flowchart
* Z-score above 3.2 9 on nightmare freque ncy; IRT = Imagery Rehearsal Therapy; IRT+ = IRT with sleep hygiene;
LDT = IRT with sleep hygiene and Lucid Dreaming Therapy; WL = waiting-list.
Intervention
Intervention
Intervention
Intervention

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Expanding IRT Self-Help for Nightmares
In the diary the variables were originally measured per
day but were transformed to a weekly period; time is thus
indicative for the relative change over one week. This does
not apply to nightmare frequency per week which was log-
transformed to meet the assumption of normality. One diary
from the IRT+ condition was excluded from the analyses be-
cause of a z-score of above 3.29 (18 nightmares in the rst
week of the diary); two diaries from IRT+ and three from LDT
were excluded because the participants completed only the
rst (two) week(s). A signicance level of p < .05 (two-sided)
was used throughout the study.
3. Results
3.1. Attrition rates
At 4-week follow-up, 29 (43.2%) participants in the IRT, 42
(56.0%) in the IRT+, 34 (47.9%) in the LDT, and 46 (74.2%)
in the waiting-list condition completed the questionnaire. A
higher percentage of participants in the waiting-list condi-
tion returned the questionnaire than in the IRT (p < .001),
IRT+ (p < .05), and LDT condition (p < .01). No signicant
differences in dropout were found between the interven-
tion conditions. In the LDT condition, older participants
(M = 39.8; SD = 15.7 versus M = 33.5; SD = 12.6) and fe-
males (male: n = 6; 35.3%; female: n = 28; 51.9%; p < .05)
Table 3. Means of Questionnaire Variables at Baseline, 4, 16, and 42 Weeks After the Intervention.
Baseline
M (SD)
4 weeks
M (SD) d - 1
16 weeks
M (SD) d - 2
42 weeks
M (SD) d - 3
Nightmare
frequency
week
IRT 6.45 (5.17) 2.48 (3.41) -0.77*** 2.14 (3.15) -0.83*** 1.47 (1.26) -0.96***
IRT+ 5.56 (4.32) 4.12 (4.60) -0.33*** 5.73 (7.94) 0.04ns 4.37 (5.28) -0.28**
LDT 6.08 (4.40) 4.03 (5.21) -0.47*** 4.12 (4.59) -0.45*** 4.50 (5.59) -0.36**
WL 6.42 (4.55) 4.78 (4.31) -0.36**
Nights with
nightmares
per month
IRT 16.01 (8.59) 8.36 (7.44) -0.89*** 7.18 (8.29) -1.03*** 4.05 (2.97) -1.39***
IRT+ 15.97 (8.56) 11.74 (9.52) -0.49*** 12.36 (10.28) -0.42* 11.47 (10.71) -0.53**
LDT 17.04 (9.19) 10.32 (8.89) -0.73*** 11.12 (9.82) -0.64*** 9.50 (9.82) -0.82***
WL 16.15 (8.53) 13.83 (9.26) -0.27ns
Nightmare
distress
IRT 16.18 (4.07) 12.18 (3.95) -0.98*** 11.27 (4.08) -1.21*** 10.59 (3.48) -1.37***
IRT+ 14.72 (4.55) 13.34 (4.87) -0.30*** 12.86 (5.09) -0.41φ12.22 (4.47) -0.55**
LDT 16.06 (4.79) 13.32 (4.40) -0.57*** 13.56 (5.13) -0.52*** 13.18 (5.00) -0.60*
WL 14.95 (4.40) 14.54 (4.46) -0.09ns
Depression
IRT 19.76 (9.84) 13.96 (8.71) -0.59*** 13.24 (8.71) -0.66*** 12.68 (7.36) -0.72**
IRT+ 19.76 (10.52) 17.41 (12.78) -0.22** 15.68 (11.08) -0.39** 16.79 (10.02) -0.28ns
LDT 19.52 (10.13) 13.44 (10.45) -0.60** 14.20 (12.83) -0.53ns 13.83 (12.11) -0.56ns
WL 20.08 (12.09) 19.28 (12.84) -0.07ns
Anxiety
IRT 47.19 (11.69) 42.37 (10.53) -0.41* 41.52 (10.26) -0.49** 41.05 (10.71) -0.53**
IRT+ 46.77 (10.69) 43.32 (12.19) -0.32*** 40.86 (11.55) -0.55** 42.05 (10.08) -0.44*
LDT 47.86 (11.92) 41.97 (12.86) -0.49** 40.92 (13.81) -0.58* 41.54 (13.30) -0.53ns
WL 46.73 (12.49) 45.76 (13.06) -0.08ns
PTSD
IRT 30.98 (16.11) 34.79 (17.37) 0.24ns 23.29 (21.00) -0.48ns 23.92 (16.60) -0.44ns
IRT+ 26.82 (15.74) 33.44 (18.56) 0.42ns 25.79 (15.64) -0.07ns 21.64 (19.04) -0.33ns
LDT 25.51 (17.68) 18.74 (14.84) -0.38ns 22.41 (15.41) -0.18ns 25.06 (16.33) -0.03ns
WL 29.69 (17.99) 34.41 (19.08) 0.26ns
Sleep
quality
IRT 5.49 (1.53) 5.93 (1.77) 0.29** 6.50 (1.57) 0.66*** 6.84 (1.42) 0.88***
IRT+ 5.48 (1.45) 5.79 (1.69) 0.21** 5.86 (1.64) 0.27** 6.05 (1.43) 0.40***
LDT 5.42 (1.35) 6.15 (1.37) 0.54*** 6.28 (1.43) 0.64*** 6.46 (1.32) 0.77***
WL 5.69 (1.43) 6.15 (1.07) 0.32**
Note. * = p < .05; ** = p < .01; *** = p < .001; φ = p .05 - .06; IRT = Imagery Rehearsal Therapy; IRT+ = IRT with sleep hygiene; LDT =
IRT with sleep hygiene and Lucid Dreaming Therapy; WL = waiting-list.

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International Journal of Dream Research Volume 3, No. 2 (2010)116
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were more likely to complete the questionnaire.
At 42-week follow-up, 19 (28.4%) participants in the IRT,
19 (25.3%) in the IRT+, and 24 (33.8%) in the LDT condition
completed the questionnaire.
3.2. Questionnaire data
At 4-week follow up, IRT was superior in ameliorating night-
mare frequency and nightmare distress compared to IRT+
(p < .05) and the waiting-list (p < .001). Moreover, it was
effective in ameliorating depression compared to the wait-
ing-list condition (p < .05). At 4-week follow-up, LDT was
effective on nights with nightmares compared to waiting-list
condition (p < .01).
At 42-week follow-up IRT was superior on all nightmare
variables compared to the two other conditions (p < .05).
Pre-post test means can be found in Table 3 and Figure 2;
changes in Cohen’s d in Table 4.
Table 4. Changes Between Conditions in Cohen’s d for Nightmare and Secondary Variables in Questionnaire 4 (post-1)
and 42 (post-3) Weeks After the Intervention.
Nightmare
frequency
Nights with
nightmares
Nightmare
distress Depression Anxiety
PTSD
complaints
Sleep
quality
Post -1
IRT * IRT+ 0.50* 0.52φ0.53* 0.31ns 0.12ns 0.32ns -0.05ns
IRT * LDT 0.42ns 0.21ns 0.45ns 0.14ns 0.13ns -0.61ns 0.08ns
IRT * WL 0.56*** 0.83*** 0.79*** 0.57* 0.32ns -0.06ns -0.08ns
IRT+ * LDT -0.09ns -0.30ns -0.07ns -0.17ns 0.01ns -0.93* 0.14ns
IRT+ * WL 0.07ns 0.31ns 0.24ns 0.28ns 0.21ns -0.37ns -0.03ns
LDT * WL 0.16ns 0.59** 0.30ns 0.44φ0.19ns 0.52φ-0.17ns
Post-3
IRT * IRT+ 0.80** 0.89*** 0.43** 0.21ns 0.22ns 0.18ns -0.41ns
IRT * LDT 0.78** 0.68** 0.60*** 0.24ns 0.15ns 0.35ns -0.33ns
IRT+ * LDT -0.02ns -0.17ns 0.16ns 0.03ns -0.06ns 0.17ns 0.09ns
Note. * = p < .05; ** = p < .01; *** = p < .001; φ = p .05 - .06; signicance levels were calculated based on multilevel regression coefci-
ents; Nightmare frequency was z-log transformed; IRT = Imagery Rehearsal Therapy; IRT+ = IRT with sleep hygiene; LDT = IRT with
sleep hygiene and Lucid Dreaming Therapy; WL = waiting-list.
Table 5. Pre-post Measurements on Diary Variables With Corresponding Cohen’s d.
Week 1 Week 6 Δ d compared to
nM SD nM SD d IRT IRT+
Nightmare
frequency
week
IRT 16 4.00 (2.25) 16 1.50 (1.71) -1.11
IRT+ 13 3.62 (1.98) 13 1.77 (1.01) -0.93 0.31
LDT 14 3.36 (2.44) 14 2.14 (2.88) -0.50 0.55 0.28
Nights with
nightmares
IRT 16 3.56 (1.82) 16 1.50 (1.71) -1.13
IRT+ 13 3.38 (2.06) 13 1.77 (1.01) -0.78 0.24
LDT 14 3.14 (2.14) 14 2.00 (2.54) -0.53 0.46 0.23
Sleep quality
IRT 15 4.52 (1.21) 15 4.70 (1.19) 0.14
IRT+ 13 4.78 (1.16) 12 4.79 (1.34) 0.02 -0.11
LDT 14 4.71 (0.71) 13 5.10 (1.19) 0.54 0.14 0.26
Nightmare
intensity
IRT 15 3.88 (1.54) 11 4.62 (1.79) 0.39
IRT+ 13 4.19 (1.26) 11 4.35 (1.16) 0.24 -0.25
LDT 13 4.29 (1.51) 8 2.66 (0.99) -1.07 -2.26*** -2.05*
Note. IRT = Imagery Rehearsal Therapy; IRT+ = Imagery Rehearsal Therapy with sleep hygiene; LDT = IRT with sleep hygiene and
Lucid Dreaming Therapy; * p < .05; ** p < .01; *** p < .001; Nightmare frequency was z-log transformed.

International Journal of Dream Research Volume 3, No. 2 (2010) 117
D
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Expanding IRT Self-Help for Nightmares
3.3. Diary data
Multilevel regression analyses showed that all conditions
signicantly decreased nightmare frequency (p < .05).
Nights with nightmares also decreased in all conditions, but
only for IRT this reduction was signicant (p < .05; Table 5,
6). The IRT and IRT+ condition appeared superior compared
to LDT in ameliorating nights with nightmares, however, be-
tween group differences were insignicant (Table 6, Figure
3). LDT seemed superior on sleep quality compared to the
two other conditions; however, this increase was insigni-
cant on all accounts (p > .05). LDT demonstrated superior
effects (p < .05) in comparison to the two other conditions
on mean nightmare intensity; IRT had a negative effect on
mean nightmare intensity (Table 5, 6; Figure 3).
4. Discussion
In this study we set out to investigate whether expanding
IRT with sleep hygiene and lucid dreaming increases ef-
cacy. To our surprise, both LDT and IRT+ showed a smaller
decrease in nightmare measures compared to IRT. More-
over, IRT was the only condition that convincingly proved
itself compared to the waiting-list. In contrast to our expec-
tations, IRT seems to be the most effective self-help treat-
ment of all intervention conditions.
Before we discuss the implications of these ndings in de-
tail we want to address some limitations of this study. Low
power was probably a reason that some of the observed
differences were not signicant (such as the insignicant
differences on the secondary measures). Moreover, this
study suffered from a higher dropout rate than our former
study. We think this might be because in the former study
a self-help intervention for nightmares was delivered for the
rst time in the Netherlands; volunteers participating in that
study might have been more motivated. With multiple impu-
tations we tried to correct for these dropout effects (Sterne
et al., 2009). However, measurements that are missing can-
not be replaced; they can only be estimated. Therefore, the
results are less reliable, particularly for the long term mea-
surements. This implicates that conclusions are preliminary.
Table 6. Multilevel Regression Coefcients for Diary Variables
Nightmare frequency
per week
Nights with
nightmares
Mean nightmare
intensity
B SE B SE B SE
IRT
Constant -0.48 (0.14)*** -0.85 (0.32)** 1.63 (0.32)***
Time -0.20 (0.04)*** -0.69 (0.22)* 0.13 (0.24)φ
Time2- - 0.06 (0.04)ns - -
Baseline 0.68 (0.10)*** 0.90 (0.05)*** 0.69 (0.07)***
IRT+ ns ns ns ns -0.45 (0.24)φ
IRT+ *time ns ns ns ns ns ns
IRT+ *time2ns ns ns ns - -
LDT ns ns ns ns -1.07 (0.24)***
LDT*time ns ns ns ns -0.36 (0.11)***
LDT*time2ns ns ns ns - -
IRT+
Constant -0.34 (0.14)* -0.85 (0.30)*** 1.18 (0.35)***
Time -0.14 (0.04)*** -0.89 (0.24)*** 0.01 (0.07)ns
Time2- - 0.12 (0.05)**
LDT ns ns ns ns -0.63 (0.24)*
LDT*time ns ns 0.56 (0.34)φ-0.24 (0.11)*
LDT*time2ns ns -0.09 (0.06)ns ns ns
LDT
Constant -0.28 (0.13)* -0.38 (0.32)ns 0.55 (0.35)ns
Time -0.13 (0.04)*** -0.33 (0.23)ns -0.234 (0.08)**
Time2 - - 0.03 (0.04) - -
Note. IRT = Imagery Rehearsal Therapy; IRT+ = Imagery Rehearsal Therapy with sleep hygiene; LDT = IRT with sleep hygiene and
Lucid Dreaming Therapy; φ = p < .1; * p < .05; ** p < .01; *** p < .001; Nightmare frequency was z-log transformed.

Expanding IRT Self-Help for Nightmares
International Journal of Dream Research Volume 3, No. 2 (2010)118
D
IJoR
Nonetheless, the general pattern in the questionnaire data
was clear. On all accounts IRT performed better (however,
not always signicantly so) than IRT+ and LDT. In our former
study (Lancee et al., 2010a), we found exposure and IRT to
be equally effective, and we suggested that exposure might
be the key element in treating nightmares. In this study, we
found that expanding IRT with hygiene and/or LDT seems
to deteriorate efcacy. This was not expected because LDT
has showed to be effective in treating nightmares (Spoor-
maker & van den Bout, 2006) and targeting sleep has been
empirically validated in people suffering from insomnia (Mo-
rin et al., 1999). Adding these elements in a self-help format
might confuse participants and as a consequence they may
employ only parts of the separate treatments, thereby failing
to exercise the proposed key element of nightmare treat-
ment: exposure.
Employing stand alone LDT (or the current LDT protocol
without sleep hygiene) could have improved treatment out-
come. The instructions of the LDT section where short and
could have been too minimal, although they were in line with
previous protocols that could successfully induce lucidity
in a subgroup of participants (Spoormaker &
van den Bout, 2006; Spoormaker et al., 2003).
However, an interaction effect may have affect-
ed our results: It may be detrimental instead of
additive to learn LDT in addition to IRT because
of complexity and self-efcacy reasons. In any
case, LDT appears more difcult to learn than
IRT, and this would suggest that a self-help for-
mat may not be the most optimal treatment de-
livery method for LDT because support from a
therapist is essential to mastering lucid dream-
ing. Our recommendation is that future lucid
dreaming research uses a face-to-face setting
to compare original IRT with original LDT.
Another surprising nding was that adding a
sleep hygiene section did not enhance treat-
ment efcacy, not even on sleep quality. This
is in contrast to uncontrolled treatment studies
whereby a combined approach for insomnia
and nightmares showed promising results (e.g.
Krakow et al., 2001; Swanson et al., 2009). In
the self-help format, the sleep hygienic guide-
lines (such as getting out of bed when unable
to fall a sleep) might have provided a more
intrusive / difcult treatment module that may
have confused participants, or if adherence to
this module could not be sustained, a reduced
motivation to adhere to other treatment mod-
ules. It is possible that in order to improve sleep
hygiene directly a more elaborate sleep inter-
vention and/or face-to-face contact is required.
The effects observed in the questionnaire
data were largely similar in the diary data: All
conditions ameliorated nightmare frequency as
measured by a diary. No signicant improve-
ments were found by including sleep hygiene
to IRT. Moreover, The IRT and IRT+ condition
were superior compared to LDT in ameliorat-
ing nightmare frequency measures; the lack
of power was probably the reason that these
differences remained insignicant. The oppo-
site effect was found for the mean nightmare
intensity, where LDT had a larger decrease on
nightmare intensity compared to IRT and IRT+
(IRT even had an increase). IRT might only ameliorate the
low intensity nightmares; leaving the high intensity night-
mares unchanged. Another explanation could be that LDT
has more effect on nightmare intensity, because nightmare
sufferers achieve a sense of control with the lucid dreaming
technique. These diary data should be handled cautiously
as well, but as diaries can be seen a more objective form of
measurements (Levin & Nielsen, 2007) future studies should
try to nd ways to limit attrition in diaries.
Nonetheless, all intervention conditions showed an effect
on nightmare measures, but only IRT showed a signicant
effect compared to a waiting-list control condition. It seems
that for self-help therapy, exposure and IRT are the currently
the best available treatments for nightmares. IRT may be a
treatment that is more appealing to patients as it provides
a more positive, empowering manner to perform exposure.
Self-help therapy for nightmares is a promising technique,
especially because of its cost effectiveness and ability to
reach a large number of nightmare sufferers.
Figure 2. Nightmare Frequency per Week, Nights With Nightmares
per Month, and Nightmare Distress at Baseline, 4 Weeks (post-1), 16
Weeks (post-2), and 42 Weeks (post-3) After Treatment..

International Journal of Dream Research Volume 3, No. 2 (2010) 119
D
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Expanding IRT Self-Help for Nightmares
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