An Exploratory Study of the Relationship Between Substance Use, Sleep Disturbances and Reward Sensitivity - A Randomized Control Trial of Cognitive Behavioral Therapy for Insomnia
Phase: NA
Conditions: Substance Abuse, Sleep Disturbances
Sponsor: Kwai Chung Hospital

Running Head : SUBSTANCE USE, SLEEP DISTURBANCES, AND REWARD 
SENSITIVITY 
Version No: 4 
Date: 29 May 2025 
 
 
 
 
 
Research Protocol 
 
An Exploratory Study of the Relationship between Substance Use, Sleep Disturbances and 
Reward Sensitivity – A Randomized Control Trial of Cognitive Behavioral Therapy for 
Insomnia 
Yeung Wing Chun, Fritz 
Clinical Psychologist 
Kwai Chung Hospital 
 
 

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Table of Contents 
Introduction ................................................................................................................................ 4 
Sleep Disturbances and Substance Misuse ........................................................................ 5 
Reward Sensitivity in Individuals with Sleep Disturbances and Substance Misuse ......... 6 
Brief Behavioral Treatment for Insomnia in People with Substance Misuse .................... 8 
Summary .......................................................................................................................... 10 
Hypotheses ....................................................................................................................... 11 
Methodology ............................................................................................................................ 11 
Participants ....................................................................................................................... 11 
Measures .......................................................................................................................... 12 
Interventions .................................................................................................................... 16 
Fidelity Check of Interventions ....................................................................................... 17 
Procedure ......................................................................................................................... 18 
Planned Data Analysis ..................................................................................................... 18 
Power Analysis ................................................................................................................ 20 
Primary and Secondary Outcome ............................................................................................ 20 
Direct Access to Source Data/Documents ............................................................................... 21 
Data Handling and Record Keeping ........................................................................................ 21 
Financing and Insurance .......................................................................................................... 22 
Publication Policy .................................................................................................................... 22 
Ethical Concern ........................................................................................................................ 22 
References ................................................................................................................................ 23 
 
 
 

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Abstract 
Disruption in reward sensitivity was known as a key factor in the development and 
maintenance of Substance Use Disorder (SUD). Past research found blunted responses to 
neutral stimuli and heightened responses to substances in patients with substance misuse. 
Meanwhile, sleep disturbances often presented in patients with substance misuse and were 
found to alter brain reward circuitry. The objective of the present study investigates the effect 
of brief Cognitive Behavioral Therapy for Insomnia in individuals with substance use. 
Changes in sleep parameters, substance use, and measurements of reward sensitivity are 
compared between treatment group and active control group. The findings of this study will 
contribute to a better understanding of the underlying mechanism of substance use and 
inform treatment formulation. 
 
 
 
 

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Introduction 
Substance misuse is a significant social and mental health concern in Hong Kong, as 
it incurs substantial expenses to the public health system (Liu, 2019). In a recent local study, 
a trend of increasing number of elderly substance abusers and increasing severity of drug 
abuse in middle-aged and younger adolescent groups was found (Liu, 2019). Nonetheless, 
substance use disorder is often considered a difficult condition to treat. First, co-occurrence 
of other psychiatric symptoms was common in people with substance use, possibly because 
of shared vulnerabilities between substance use and psychiatric disorders (Koob, 1992). The 
“dual diagnosis” complicated the clinical picture, making it difficult for clinicians to decide 
treatment focus. Individuals with substance misuse were also found to have high rates of 
relapse using traditional treatment approaches that focused on reduction of substance use 
(Koob & Volkow, 2016). For example, previous research found that 40% to 60% of 
individuals with substance use disorder had relapse for substance use within 1 year after 
seeking treatment (Bowen et al., 2014). It was explained that the underlying needs of the 
individuals, e.g., mood problems, sleep disturbances, and family problems, were not 
adequately addressed by traditional relapse prevention approaches that mainly focused on 
increasing avoidance-based goals to reduce triggering substance use (Bowen et al., 2014). 
Another difficulty was that individuals with substance misuse tended to show limited 
willingness to receive traditional treatment for quitting substance use. Individuals with 
substance misuse could see limited values to receive treatment for managing substance use 
(McHugh et al., 2010). They might be in denial of the severity of consequences associated 
with substance use (McHugh et al., 2010). Stigma associated with substance use also could 
maintain their sense of shame and reluctance to disclose substance use (Kelly et al., 2017). In 
view of these difficulties, it was suggested that effective treatment approaches for substance 

SUBSTANCE USE, SLEEP DISTURBANCES, AND REWARD SENSITIVITY 
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misuse should consist of a number of active treatment components to maintain individuals’ 
motivation to engage in treatment (McHugh et al., 2010). 
Sleep Disturbances and Substance Misuse 
Sleep disturbances were often reported as co-occurring symptoms in the substance use 
population across different types of users. In a sample of 123 treatment seeking patients with 
alcohol use disorder, 45% of participants reported moderate level of insomnia symptoms in 
Insomnia Severity Index, and 29% reported their symptoms to be mild (Chaudhary, 2015). In 
another sample of 303 treatment seeking samples, 88% of patients with alcohol use disorder 
reported insomnia during the early recovery stage (Kolla et al., 2020).  Over 75% of cannabis 
users in recovery reported sleep disturbances and used tranquilizers, alcohol, or relapsing to 
cannabis to improve sleep quality (Copersino et al., 2006). Stein et al. (2004) found that 85% 
of patients with opioid use disorder who received methadone maintenance rated a score of 6 
or higher on the Pittsburgh Sleep Quality Index (PSQI), indicating a significant level of sleep 
disturbances. Eight-four percent of patients who were admitted to hospital for detoxification 
of benzodiazepine, alcohol, heroin, cocaine, and cannabis reported to have insomnia 
symptoms during active substance use (Grau-López et al.,2016). Chakravorty and colleagues 
(2018) opined that the direct effect of substance use on sleep, withdrawal syndromes of 
substance use, and co-occurring psychiatric conditions were all the possible contributing 
factors of sleep disturbances.  
Furthermore, it was found that sleep disturbances experienced in adolescence 
predicted substance use later in the individuals’ life. Adolescents who self-reported to 
experience symptoms of insomnia were more likely to report use of alcohol, cannabis, and 
drugs other than cannabis in adulthood (Roane & Taylor, 2008). In another longitudinal 
study, consistency of sleep pattern and sleep duration predicted the onset of substance use 
two years later among teenagers (Pasch et al., 2012). Hasler and colleagues (2014) also found 

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that teenagers who reported more variation in sleep times at baseline reported more 
symptoms of alcohol use disorder at 3- and 5-year follow-up. 
Conroy and Arnedt (2014) proposed that the relationship between substance use and 
sleep disturbances might be bi-directional. Rosenblum (2017) suggested that individuals with 
sleep problems could be more prone to self-medication with substances, while substance use 
might further interfere with sleep. In an experience sampling study, the temporal relationship 
between craving for substance use and sleep difficulties was studied (Freeman & 
Gottfredson, 2018). It was found that worse sleep predicted a higher level of drug cravings, 
while stronger cravings also significantly predicted worsened sleep outcomes. It was 
hypothesized that sleep loss and circadian misalignment could disrupt reward-related brain 
function and in turn, contribute to substance use (Hasler et al., 2014).  
Reward Sensitivity in Individuals with Sleep Disturbances and Substance Misuse 
In earlier years, researchers conceptualized that individuals’ responsiveness to 
rewarding stimuli were governed by the Behavioral Activation System (BAS; Gray, 1987). 
Individuals with a more reactive BAS were believed to be more motivated to approach and 
engage with pleasurable stimuli, and they experience stronger positive emotions in response 
to rewards (Carver & White, 1994). These individuals were believed to have higher reward 
sensitivity. In recent years, researchers have adopted brain imaging to investigate the brain's 
response to pleasurable stimuli (Volkow et al., 2010). Ventromedial prefrontal cortex and 
ventral striatum were considered a key brain region responsible for reward processing (Pujara 
et al., 2016). It was found that sleep disturbances altered brain reward circuitry (Motomura et 
al., 2017). In patients with chronic insomnia, they showed reduced activation in ventral 
striatum in response to natural cues such as food or money (Motomura et al., 2021). Youth 
with insomnia disorder was found to have blunted reward sensitivity and inflexibility in 
decision-making in an experimental monetary paradigm (Ling et al., 2022). Mullini et al. 

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(2013) found that temporary sleep deprivation produced aberrant functioning in the neural 
reward circuit.  
Dysfunction in reward circuitry was also found in individuals with substance misuse. 
Dugré, Orban, and Potvin (2023) reviewed 96 studies, which investigated brain imaging of 
5757 subjects in total, and found highly consistent findings of hyper-connectivity of 
ventromedial prefrontal cortex and ventral striatum in individuals of different substance 
misuse across research studies. Heightened reward sensitivity to substances was supported by 
the assessment of dopamine neurocircuitry (Volkow & Blanco, 2023).  Individuals with 
substance use disorder showed consistent reduction in striatal D2 receptors which led to 
increased sensitivity towards substance use (Volkow & Blanco, 2023). Researchers also 
found that individuals with substance dependence showed poorer performance in the Iowa 
Gambling Task (Fridberg et al., 2010; Grant et al., 2000). These individuals were found to 
favor choices that brought about small, immediate gains but larger losses over time in the 
Iowa Gambling Task, which supported the presence of dysfunction in reward sensitivity 
(Fridberg et al., 2010; Grant et al., 2000). In a sample of participants with comorbid bipolar 
disorder and stimulant use disorder, the poorer performance in the Iowa Gambling Task 
predicted heavier use in stimulants at a future time point (Nejtek et al., 2013).  
Some researchers focused on studying the reward deficiency hypothesis in individuals 
with substance use (Bowirrat & Oscar-Berman, 2005), in reference to a reduction in 
sensitivity towards natural stimuli, such as food or social cues. The reduction in sensitivity to 
natural stimuli was believed to contribute to a higher relative-reinforcing value of the hedonic 
effects of drug consumption. Clinical brain-imaging studies supported the hypothesis, as a 
decrease in activation of brain regions implicated in the processing of food, sexual, or 
monetary rewards was found in individuals with addiction (Volkow & Blanco, 2023). 

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Considering these findings, alternation in reward sensitivity likely played a crucial role in the 
relationship between sleep disturbances and substance misuse (Conroy & Arnedt, 2014).  
Brief Behavioral Treatment for Insomnia in People with Substance Misuse 
As sleep problems were found to affect reward sensitivity and substance misuse, 
researchers also started investigating the effect of psychological treatment on insomnia 
among individuals with substance misuse. Guo et al. (2023) opined that use of different 
substances all resulted in changes in sleep and improving sleep quality should serve as a 
complementary treatment target for patients with substance misuse. Furthermore, 
psychological interventions were considered a safer alternative in treating sleep problems to 
pharmacological interventions (Speed et al., 2022). Targeting symptoms of insomnia in 
psychological treatment was also considered a less stigmatizing focus compared to 
conventional substance misuse treatment (Hasler et al., 2014), and would likely benefit initial 
patient engagement.  
Cognitive Behavioral Therapy for Insomnia (CBTi) was set to address the underlying 
causes of insomnia and improve sleep quality (Perlis et al., 2005). It covered several core 
cognitive and behavioral techniques including stimulus control, sleep restriction, and 
cognitive restructuring. There has been strong evidence supporting the effect of CBTi in 
reducing symptoms of sleep disturbances. In a meta-analysis, CBTi was found to be as 
effective as pharmacological interventions for patients with primary insomnia and its effect 
was more lasting (Mitchell et al., 2012). Specifically targeting the substance misuse 
population, several studies reported substantial effects of CBTi. For example, Mijnster et al. 
(2022) reviewed the effectiveness of CBTi for individuals with alcohol use and hypnotic 
dependence and found a general trend of reduction in insomnia symptoms as measured by 
Insomnia Severity Index. Arnedt et al. (2011) found a significantly larger reduction of 
insomnia severity in recovering individuals with alcohol use who received CBTi compared to 

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those receiving placebo interventions. In cannabis users, Arnedt et al. (2023) found a 
significantly larger reduction of insomnia severity in those who received CBTi compared 
with those who received sleep hygiene education only. Miller et al. (2023) found that CBTi 
produces statistically significant reductions of large effect sizes in insomnia severity and 
substance use among adults seeking treatment for substance use, although the study did not 
have a control group to account for potential confounds. Among cannabis users in the study 
of Arnedt et al. (2023), more significant reduction in cannabis use at the 8th week post-
treatment follow-up was found in participants who received telephone-based CBTi than in 
the active control group who received sleep hygiene education. Overall, CBTi appeared to be 
effective in reducing both insomnia symptoms and substance use among individuals with 
substance misuse. Nonetheless, maintaining participation in standard CBTi of 6 to 8 weeks 
might be challenging. Among a sample of 528 patients attending sleep clinic, it was found 
that 40% of participants did not complete all 7 in-person sessions of CBTi (Ong, Kuo & 
Manber, 2009). In an 8-week CBTi study focusing on patients with alcohol dependence, the 
dropout rate of intervention group exceeded 30% (Arnedt et al., 2011).  
Researchers developed brief versions of CBTi while maintaining its effectiveness. 
Ellis, Cushing, and Germain (2015) found that a single-session CBTi produced significant 
improvements in Insomnia Severity Index scores among patients with sleep problems, and 
reported medium to large effect size when comparing intervention group to a control group. 
Bishop et al. (2021) conducted session-by-session analysis and found that majority of the 
treatment effect on sleep disturbances occurred over the first two sessions of CBTi that 
focused on stimulus control and sleep restriction. Another treatment protocol, the Brief 
Behavioral Treatment for Insomnia (BBTI) reduced the number of in-person visits to 2 
sessions, and focused on the early implementation of stimulus control and sleep restriction 
principles, similar to the approach used in CBT-I (Gunn, Tutek & Buysse, 2019). However, 

SUBSTANCE USE, SLEEP DISTURBANCES, AND REWARD SENSITIVITY 
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unlike CBT-I, BBTI did not target inaccurate beliefs and attitudes regarding sleep, insomnia, 
or the effects of poor sleep. A meta-analysis reported that Brief Behavioral Treatment for 
Insomnia (BBTI) leads to significant improvements in insomnia, as measured by subjective 
sleep assessments and the benefits were particularly obvious within 1 to 2 months of 
implementation (Kwon et al., 2022). BBTI was also initially used in the substance use 
population. In a pilot study focusing on individuals exposed to trauma, BBTI showed large 
effect sizes in reducing insomnia symptoms and cannabis use when comparing to waitlist 
control group at 3-month follow up (Short, Zvolensky & Schmidt, 2021). 
Summary 
In summary, research literature suggested that there is a high prevalence of sleep 
disturbances among individuals with substance misuse. Both substance use and sleep 
problems are believed to affect reward sensitivity, while reward sensitivity is considered a 
key factor in maintaining substance use. Recent research has shown that brief CBTi 
effectively reduces the severity of insomnia in patients with substance use. Several studies 
also found a positive impact of brief CBTi on reducing substance use. Nonetheless, the 
hypothesis that sleep problems disrupt reward-related brain function and contribute to 
substance use has not been adequately tested.  
Therefore, the purpose of the proposed study is among the first attempts to examine 
the relationships among substance use, sleep disturbances, and reward sensitivity. It also aims 
to investigate whether reward sensitivity plays a role in the mechanism by which sleep 
interventions help reduce substance misuse. Although focusing on managing sleep problems 
is considered a less stigmatizing and safer treatment for managing sleep problems among 
individuals with substance misuse (Hasler et al., 2014), it is important to highlight that the 
effect and mechanism of sleep interventions on individuals with substance use problems have 
not been studied in the Hong Kong community. This study will provide evidence on the 

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significance of sleep interventions in treating substance misuse, addressing patient needs 
more effectively and improve treatment engagement. 
Hypotheses 
The present study is separated into two phases to test four hypotheses on the 
associations among sleep disturbances, reward sensitivity, and substance use. 
Hypothesis 1: Brief CBTi group shows a larger improvement in sleep quality, 
reduction in insomnia symptoms, and reduction in symptoms of substance use than active 
control group (i.e., sleep education group). 
Hypothesis 2: Changes in reward sensitivity from baseline to post-treatment mediate 
the effect of intervention group assignment (i.e., brief CBTi or Active Control) on changes in 
substance use from baseline to post-treatment and those from baseline to one-month follow-
up. 
Methodology 
Participants 
Based on power analysis, a total of 154 participants will be recruited. All participants 
will be recruited from Substance Abuse Assessment Clinic and other psychiatric out-patient 
clinics of Kwai Chung Hospital. Individuals with problematic substance or alcohol use in the 
past 3 months and sleep disturbances will be recruited. Specifically, the Tobacco, Alcohol, 
Prescription medication, and other Substance use (TAPS) and Insomnia Severity Index (ISI) 
tools will be used to screen participants for eligibility. Scores higher than or equal to 1 in 
both TAPS-1 and TAPS-2 indicates problematic substance use in the past 3 months and a 
score higher than or equal to 8 on the ISI indicates presence of subclinical insomnia 
symptoms. Participants who meet these criteria will be considered for inclusion in the study. 
Participants will be randomly assigned, in an open-label format and at a 1:1 ratio, to receive 
either brief Cognitive Behavioral Therapy for Insomnia (CBTi), or Sleep Education (SE). 

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There are several exclusion criteria. Individuals who cannot understand Cantonese, 
cannot read Traditional Chinese, or cannot provide informed consent due to, for example, 
intoxication or abnormal mental state will not be recruited. Individuals will also be excluded 
from the studies if they report abnormal or unstable mental states, such as active psychotic 
symptoms or acute intoxication, at any point of the study. Individuals who work overnight or 
have rotating shifts and individuals who report regular use of hypnotics, pregnancy or 
medical conditions (e.g. sleep apnea) that may have a severe impact on sleep will be excluded 
from this study as well. 
At any stage of the study, if immediate intervention needs (e.g. suicidal risk) are 
identified, the individuals will be contacted as soon as feasible. Immediate intervention needs 
may be indicated by participants’ responses to Question 27 and 28 of the General Health 
Questionnaire, “You found yourself wishing you were dead and away from it all?” and “You 
found that the idea of taking your own life kept coming into your mind?”, or clinical 
observations or self-reported signs of unstable mental state, such as severe withdrawal 
symptoms or psychotic symptoms. The participant will be contacted for further assessment 
by Clinical Psychologist, and referred to appropriate services if needed, within one working 
day. 
Measures 
The Tobacco, Alcohol, Prescription medication, and other Substance use (TAPS; McNeely 
et al., 2016) 
The Tobacco, Alcohol, Prescription medication, and other Substance use (TAPS) 
Tool includes an initial screening section (TAPS-1) and a subsequent brief assessment 
(TAPS-2) for individuals who receive a positive screening result. This tool aims to identify 
problematic substance use over the prior three months. For screening illicit and prescription 

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drug misuse using a cut-off score of 1, sensitivity varied between 63% and 82%, while 
specificity exceeded 93% (McNeely et al., 2016). 
General Health Questionnaire (GHQ-28; Goldberg & Hillier, 1979) 
GHQ-28 is a self-report questionnaire to screen for potential psychological disorders 
in terms of difficulties in performing everyday activities and presences of distressing 
symptoms (Goldberg & Hillier, 1979). Test-retest reliability of GHQ-28 is high, ranging from 
0.78 to 0.90 (Robinson and Price, 1982), and it shows good correlation with other mood 
measurement tools (Robinson and Price, 1982; Sakakibara et al., 2009). 
Insomnia Severity Index (ISI; Bastien, Vallières, & Morin, 2001) 
ISI is a well-validated self-report questionnaire specifically designed to assess the 
severity of insomnia symptoms. It measures the perceived severity of insomnia-related 
difficulties, including difficulties falling asleep, staying asleep, and early morning 
awakenings, as well as the impact of insomnia on daytime functioning. Insomnia Severity 
Index (ISI) shows acceptable internal consistency (Cronbach's alpha = 0.74) and satisfactory 
convergent validity, as the individual items on the ISI correlate reasonably well (r = 0.32 to 
0.91) with indicators on a sleep diary (Bastien, Vallières & Morin ,2001).  
Pittsburgh Sleep Quality Index (PSQI; Buysse et al., 1989) 
PSQI assesses overall sleep quality over a one-month period. In addition to sleep 
disturbances measured by ISI, it covers measurements on the quality of sleep, including sleep 
duration, latency, disturbances, medications, and daytime dysfunction for a comprehensive 
understanding of an individual’s sleep functioning. The test-retest reliability of PSQI is high 
(r = 0.87; Backhaus et al., 2002). It has a sensitivity of 98.7% and a specificity of 84.4% for 
assessing sleep disturbances in insomnia patients versus controls, when using a PSQI total 
score threshold of higher than 5 (Backhaus et al., 2002). 
Drug Use Disorders Identification Test (DUDIT; Berman et al., 2005) 

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The Drug Use Disorders Identification Test (DUDIT) is a self-report questionnaire 
aiming to evaluate the intensity of their drug use. It targets both use of illegal drugs and non-
medical use of prescription drugs. The DUDIT comprises 11 questions that address different 
aspects of drug use, including the frequency of use, symptoms of dependence, and negative 
outcomes linked to drug use. Based on the score on the DUDIT, the extent of drug-related 
problems will be determined, with higher scores indicating more severe drug use concerns. 
DUDIT shows satisfactory reliability and validity as a research tool (Hildebrand, 2015), with 
an internal consistency (Cronbach's α) of 0.90 or higher, adequate sensitivity (85% to 100%), 
and satisfactory specificity (75% to 92%). 
Alcohol Use Disorders Identification Test (AUDIT; Saunders et al., 1993) 
The Alcohol Use Disorders Identification Test (AUDIT) is a widely used tool for 
assessing the severity of alcohol use. It is a self-report questionnaire that consists of 10 items 
covering alcohol consumption, drinking behavior, and alcohol-related consequences. The 
AUDIT assesses the frequency and amount of alcohol consumed, signs of alcohol 
dependence, and negative outcomes stemming from alcohol use. Based on the score on the 
AUDIT, the extent of alcohol-related problems can be determined, with higher scores 
indicating more severe alcohol use concerns. AUDIT demonstrates high internal consistency 
(i.e., an average Cronbach's alpha of 0.80; de Meneses-Gaya et al., 2009). Additionally, its 
sensitivity and specificity generally exceed those of the other assessments of hazardous 
drinking (Reinert & Allen, 2007). 
Sensitivity to Reward scales from Sensitivity to Reward and Sensitivity to Punishment 
Questionnaire (SRSPQ; Torrubia et al., 2001) 
The Sensitivity to Reward Scales from SRSPQ consists of 24 items for assessing 
reward sensitivity and uses a dichotomous scale (“Yes” and “No”). Unlike other scales that 
measure reward sensitivity, items on the Sensitivity to Reward Scales assess specific rewards, 

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such as money, social rewards, sexual rewards and alcohol and substances. The use of 
specific concepts of rewards to measure reward sensitivity helps reduce ambiguity when 
interpreting results (Torrubia et al., 2001). The Sensitivity to Reward Scale demonstrates 
good internal consistency (Cronbach’s alpha = .75-.78) and test-retest reliability (r = .61-.87; 
Torrubia et al., 2001).   
Computerized Iowa Gambling Task (Bechara et al., 1994) 
The Iowa Gambling Task was originally designed to identify decision-making deficits 
in patients with lesions in the ventromedial prefrontal cortex (vmPFC) versus other brain 
areas (Bechara et al., 1994). In the task, participants are instructed to gain as much as 
possible by choosing from one of four options. They are informed that each option will yield 
a gain and possibly a penalty. They are also informed that some decks are more advantageous 
than the others. However, they are not informed that there are 100 trials in total. Two of the 
choices are disadvantageous which provide immediate large rewards but more significant 
losses eventually. The remaining two decks are more advantageous, giving modest reward 
and lower losses.  
Traditionally, the score of the Iowa Gambling Task is to index the net number of 
cards chosen from advantageous decks; however, this approach neglects the multiple 
decision-making process (Chan, 2014). To measure reward sensitivity of participants from 
their task performance appropriately, Prospect Valence Learning (PVL) model, a validated 
cognitive model of IGT (Ahn et al., 2008), will be applied. The PVL model suggests that 
participants make their card decision based on valence expectation, which is composed of 
motivational parameter and learning as well as response consistency (Ahn et al., 2008). 
Motivational parameter is further differentiated into feedback sensitivity and loss aversion 
(Ahn et al., 2008); in particular, feedback sensitivity refers to the non-linear relationship 
between the actual quantities of gain or loss and the prospect valence, and this construct 

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represents Reward Sensitivity of task performance in the present study. Previous study 
showed that the cognitive model of IGT identified significant differences in motivational 
parameters in individuals with substance use when compared with healthy controls (Fridberg 
et al., 2010). 
Client Satisfaction Questionnaire (Larsen et al., 1979) 
To better understand the participants’ subjective experiences about treatment sessions, 
participants will be invited to rate their satisfaction using an 8-item Client Satisfaction 
Questionnaire (CSQ) developed by Larsen et al. (1979) at the last treatment session. The 
CSQ is designed to assess the satisfaction levels of patients with health and human service 
systems and shows an internal consistency of Cronbach's α = .93 (Attkisson & Zwick, 1982).  
Interventions 
Both treatment groups will receive 3 in-person treatment sessions in total. Participants 
will attend 3 in-person sessions at Week 1, Week 4 and Week 8, and two telephone follow-up 
at Week 2 and Week 3. For CBTi group, the content of the sessions will be adapted from 
Perlis et al. (2005) and Gunn, Tutek & Buysse (2019) and will focus on techniques such as 
stimulus control and sleep restriction (See Table 1). Individuals will also be prescribed with 
sleep diary in each session. Sleep diary will be reviewed at the beginning of each subsequent 
session. As an active control condition, Sleep Education sessions focuses on psychoeducation 
sessions on sleep hygiene (See Table 2).   
Table 1 
Outline of Brief Cognitive Behavioral Therapy for Insomnia Group 
Session 
Outline 

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Week 1 Sleep Scheduling & 
Cognitive Strategies (60 minutes) 
Concepts of cognitive behavioral therapy will be 
introduced. Sleep restriction and stimulus control 
techniques will be introduced. Behavioral strategies 
focusing on increasing sleep drive will be discussed to 
improve sleep quality, duration, and timing. Concepts of 
maladaptive beliefs about sleep will be explained 
Week 2 & 3 Telephone Boosters 
(<20 minutes each) 
Sleep quality, diaries, daytime functioning will be 
reviewed to facilitate adherence to recommendations 
suggested at session 1. Further sleep titration will be 
conducted if indicated. 
Week 4 Progress Review (30 
minutes) 
Sleep titration will be conducted by reviewing sleep diary 
and adjusting time in bed appropriately. Understanding of 
maladaptive beliefs about sleep will be further enhanced. 
Factors related to relapse of insomnia and strategies for 
adjusting sleep patterns will be discussed. 
Week 8 Booster Session <20 
minutes) 
Sleep titration will be conducted by reviewing sleep diary 
and adjusting time in bed appropriately. 
 
Table 2 
Outline of Sleep Education Group 
Session 
Outline 
Week 1 Introduction & Sleep 
Education (60 minutes) 
Concepts of insomnia will be discussed. Sleep hygiene will 
be introduced. 
Week 2 & 3 Telephone Boosters 
(<20 minutes each) 
Key concepts from Session 1 will be discussed.  
Week 4 Progress Review (30 
minutes) 
Concepts of insomnia and sleep hygiene will be reviewed.  
Week 8 Final Booster Session 
(<20 minutes) 
Overall summary and review of sleep hygiene. 
 
Fidelity Check of Interventions 
A checklist will be adapted from Taylor et al. (2019) for the evaluation of intervention 
fidelity. The checklist will consist of behavioral descriptions on the session content. A trained 
research assistant will sit in 20% of treatment sessions at random and rate the session 
contents accordingly. 

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Procedure 
Participants will be recruited from Substance Abuse Assessment Units, and other 
psychiatric outpatients at Kwai Chung Hospital (KCH) and all research procedures will be 
carried out at the respective clinics at KCH. Recruitment poster will be displayed in these 
clinics. Participants will first complete the tools (TAPS & ISI) to screen for eligibility. 
Informed consent will be obtained from all participants before their enrolment in the study. 
Enrolled participants will be invited to further complete the self-report measures and 
gambling tasks (PSQI, AUDIT DUDIT, SRSPQ and Iowa Gambling Task) to assess sleep 
problems, substance use severity and reward sensitivity at baseline. GHQ-28 will also be 
administered to control for mood symptoms. Demographic data, including participant’s age, 
gender, marital status, employment status, education level, and use of psychiatric medication 
will also be collected. CBTi participants will go through two in-person sessions of brief CBTi 
at Week 1 and Week 4. Booster telephone follow-ups will be made at Week 2 and Week 3. 
Active Control group will receive a sleep education session at Week 1, followed by 2 weekly 
follow-up booster calls while continuing their usual treatment. Post-intervention 
measurement will be conducted at Week 4 for both groups after receiving in-person 
intervention sessions. Both groups will be re-assessed at Week 8 before a final in-person 
booster session. 
Treatment and data collection sessions will be conducted by Clinical Psychologists, 
trained Clinical Psychology trainees, or trained Psychology Assistants.  
Planned Data Analysis 
For Hypothesis 1, ANCOVA will be used. Intervention group (“Group”) would be 
entered as an independent variable. Sleep duration (“SLDU_t1”), total scores of ISI 
(“ISI_t1”), PSQI (“PSQI_t1”), (“AUDIT_t1”) and (“DUDIT_t1”) at baseline will be entered 
as covariate. Sleep duration (“SLDU_t2, “SLDU_t3”), total scores of ISI (“ISI_t2”, 

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“ISI_t3”), PSQI (“PSQI_t2”, “PSQI _t3”), (“AUDIT_t2”, “AUDIT_t3”) and (“DUDIT_t2”, 
“DUDIT_t3”) at Week 4 and Week 8 will be entered as dependent variables. Effect sizes on 
treatment-induced changes will be computed as appropriate. 
To explore the directionality of relationships among the variables in Hypothesis 2, 
cross-lagged mediation analysis will be performed using structural equation modelling. 
Standardized residualized change scores (SRCSs) will be computed for mediator (i.e., 
Reward Sensitivity) and outcome measures (i.e., Substance Use), with the effect of 
measurement at the prior time point (e.g., T2) partialled out of that for the current time point 
(e.g., T3). The SRCSs of Reward Sensitivity and Substance Use will be entered to a cross-
lagged path model (see Figures 1 and 2). 
Figure 1 
Proposed Path Analysis Model 1 for Hypothesis 2 
 
Note. “∆Reward Sensitivity T1T2” refers to the standardized residualized change scores of 
reward sensitivity measurements between baseline and Week 4. “∆Substance Use T1T3” refers 
to the standardized residualized change scores of substance use measurements between 
baseline and Week 8.  
Figure 2 
Proposed Path Analysis Model 2 for Hypothesis 2 
 

SUBSTANCE USE, SLEEP DISTURBANCES, AND REWARD SENSITIVITY 
20 
Note. “∆Reward Sensitivity T1T2” refers to the standardized residualized change scores of 
reward sensitivity measurements between baseline and Week 4. “∆Reward Sensitivity T1T3” 
refers to the standardized residualized change scores of reward sensitivity measurements 
between baseline and Week 8. “∆Substance Use T1T2” refers to the standardized residualized 
change scores of substance use measurements between baseline and Week 4. “∆Substance 
Use T1T3” refers to the standardized residualized change scores of substance use 
measurements between baseline and Week 8. 
Power Analysis 
For Hypothesis 1, CBTi appears to have a moderate to large effect (d ≥ 0.80) on 
reducing insomnia symptoms among individuals with alcohol use or cannabis use when 
compared to the active control groups (Arnedt et al., 2011; Arnedt et al., 2023). Due to the 
limited studies on CBTi’s effect on reducing substance use, we anticipate a mild to moderate 
effect of CBTi (f = 0.25) on the reduction of insomnia symptoms and substance use in 
comparing our treatment seeking sample with the control group using ANCOVA. Using 
G*Power 3.1.9.4, a minimum number of 128 participants will be required for a statistical 
power of .80 to detect an effect of .25 at an alpha level of .05 (Faul et al., 2009). Considering 
a drop-out rate of 20%, a total of 154 participants will be required. 
For Hypothesis 2, as an exploratory study to investigate the mediating effect of 
reward sensitivity on the relationship of brief CBTi and substance use, we will conduct 
analysis using all the samples collected for testing Hypothesis 1. Therefore, a minimum of 
154 participants will be required (i.e., 77 participants in brief CBTi group, and 77 participants 
in Sleep Education group). 
Primary and Secondary Outcome 
Primary outcome of the study is the effect of brief CBTi on reducing sleep problems 
(Questionnaires: Insomnia Severity Index, Pittsburgh Sleep Quality Index) and substance 

SUBSTANCE USE, SLEEP DISTURBANCES, AND REWARD SENSITIVITY 
21 
use(Questionnaire: Alcohol Use Disorders Identification Test, Drug Use Disorders 
Identification Test) after controlling for the treatment effect of Active Control.   
Secondary outcome is the mediating effect of reward sensitivity (Questionnaires & 
Computerized Task: Computerized Iowa Gambling Task, Sensitivity to Reward scales) of in 
mediating the relationship between Group assignment (CBTi or Active Control) and 
substance use (Questionnaires: Alcohol Use Disorders Identification Test, Drug Use 
Disorders Identification Test). 
Direct Access to Source Data/Documents 
For participants recruited at KCH, IRB / REC, principal investigator and KCH 
Clinical Psychologists/ Psychology Assistant assigned and approved by direct superior of 
principal investigator (i.e. SCP) will have access to personal data and study data. Co-
investigator from HKU will only have access to de-identified study data (i.e. no full names 
and HKID number included in the study data). 
Data Handling and Record Keeping 
Principal investigator will be responsible for safekeeping of the personal and study 
data during and after the study. Subjects will complete questionnaires in private room for 
privacy protection. Participants’ full names and HKID number will not be written on the 
questionnaires. For the participants recruited at KCH, hard copies of consent forms and 
questionnaires will be stored in locked cabinets within hospital premise; soft copies of the 
consent forms and questionnaires (if any) will be saved in hard drive which is encrypted with 
passcode and the hard drive will only be kept within hospital premise.  
The personal and study data will be kept for 5 years after the study. Afterwards, 
Personal data will be de-identified (i.e. full names and HKID number will be removed from 
any collected data). Any hard copies of consent forms and questionnaires will be shredded 

SUBSTANCE USE, SLEEP DISTURBANCES, AND REWARD SENSITIVITY 
22 
and disposed as confidential waste. Soft copies of the consent forms and questionnaires (if 
any) will be overwritten to ensure permanent deletion. 
Financing and Insurance 
This study does not receive any sponsor or consume extra resources at Hospital 
Authority, and no extra funding or cost will be incurred for the study. 
Publication Policy 
If the research findings are published, it will be submitted to international journals 
within 5 years after completion of this study. Under no circumstances will the research 
findings or published articles disclose any participant’s personal identity. If participants wish 
to obtain a copy of the published articles, they may contact the research team using the 
contact information provided in the consent form. 
Ethical Concern 
Since sensitive personal information such as substance use will be obtained in the 
study, data collection will be conducted in private room to protect privacy. All questionnaires 
will be de-identified to protect confidentiality (i.e. full name and HKID will not be put on 
questionnaires) and consent form will be kept separately from study questionnaires. 
Additionally, written consent will be obtained and emphasized in the consent form that 
participation will be on a voluntary basis and can withdraw any time without penalty. 
 
 
 

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23 
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