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Chronobiol Med > Volume 5(3); 2023 > Article
Kim and Lee: Cognitive Behavioral Therapy for Insomnia in Patients With Schizophrenia Without Prior Psychotic Symptom Aggravation: A Prospective Single-Arm Trial

Abstract

Objective

To determine the feasibility and efficacy of cognitive behavioral therapy for insomnia (CBT-I) in patients with schizophrenia without prior psychotic symptom aggravation.

Methods

This prospective single-arm trial included 31 patients diagnosed with schizophrenia and insomnia who received CBT-I. We provided four weekly 60-min sessions of group or individual CBT-I. All patients completed several sleep-related scale assessments before and 2, 3, and 4 weeks after treatment: the Korean version of Pittsburgh Sleep Quality Index (PSQI-K), Insomnia Severity Index (ISI), Korean version of the Epworth Sleepiness Scale (K-ESS), Dysfunctional Beliefs and Attitudes about Sleep Scale-16 (DBAS-16), and sleep diary. The primary outcome was insomnia symptom changes over the treatment period, as indicated by the PSQI-K, ISI, sleep onset latency, and total sleep time from the sleep diary. The secondary outcome was improvement in maladaptive cognition associated with sleep, as indicated by the DBAS-16.

Results

The total PSQI-K and ISI at each timepoint showed significant improvements over the CBT-I program period. The total K-ESS and DBAS-16 scores showed significant improvement over the treatment period. Sleep onset latency was significantly shortened; however, no significant changes were noted in the total sleep time and some PSQI-K subscales (sleep duration, use of sleep medication, and daytime dysfunction).

Conclusion

Our findings suggest the efficacy of CBT-I in improving insomnia symptoms, dysfunctional beliefs, and attitudes toward sleep in patients with schizophrenia with relatively stable psychotic symptoms. Therefore, further large randomized controlled trials are warranted to provide precise estimates of the effects of CBT-I in this patient population.

INTRODUCTION

Sleep difficulties are reported in 16%–80% of patients with schizophrenia [1]. Insomnia occurs frequently during the clinical course of schizophrenia, with an estimated prevalence of 23%– 44% [2-4] depending on the diagnostic criteria for insomnia. Compared to the general population, patients with schizophrenia have more severe psychopathology [5], poorer cognitive performance [6], lower quality of life [2], and a positive association with suicidal ideation and lifetime suicide attempts [7].
The relationship between schizophrenia and insomnia is often considered as bidirectional [8,9]. Schizophrenia exacerbates sleep disturbance, whereas insomnia worsens psychotic symptoms. Insomnia in patients with schizophrenia is multifactorial, given the combination of biological and environmental insults. Accordingly, numerous treatment options have been proposed for insomnia in patients with schizophrenia, such as pharmacotherapy and psychological and behavioral interventions.
Antipsychotics are often used to balance dopamine dysregulation, which is considered as the biological mechanism causing insomnia in schizophrenia [9]; they can reduce the overactivity of dopamine receptors and prevent dopamine binding. Hypnotic agents such as benzodiazepines, eszopiclone [10], and melatonin [11] are also prescribed for sleep difficulties in patients with schizophrenia [12]. However, unwanted side effects and drug interactions must be considered with these pharmacotherapeutic options. A recent study showed that individuals prefer psychological and behavioral therapy over other sleep interventions because such interventions have the potential to support and empower patients in taking responsibility for their own recovery [13]. In the general population, cognitive behavioral therapy for insomnia (CBT-I) has been proven to be more cost-effective than pharmacotherapy or no treatment [14].
Recently, studies have investigated the applicability, feasibility, and effectiveness of CBT-I in patients with persistent delusions and hallucinations [15,16], patients with schizophrenia and related psychoses with distressing psychotic symptoms [17,18], people with psychotic experiences in the general population [19], and patients admitted in a psychiatric hospital during acute crisis [20].
However, to the best of our knowledge, these studies targeted patients with overt psychotic symptoms, such as auditory hallucinations and delusions, and aimed to evaluate improvements in psychiatric symptoms. Therefore, in the present study, we aimed to evaluate the efficacy and feasibility of CBT-I in patients diagnosed with schizophrenia without prior aggravation of positive psychotic symptoms.

METHODS

Study design and participants

This was a prospective clinical pilot study conducted as a singlearm trial. Participants were recruited from the psychiatric day care hospital and outpatient clinic of Seoul Metropolitan Eunpyeong Hospital. Patients with schizophrenia who had difficulty in sleeping and wanted treatment options other than drugs were recruited. This study was approved by the Institutional Review Board of Seoul Metropolitan Eunpyeong Hospital, Korea (IRB No. Eunpyeong 2022-06). The researchers explained the aims and methods of the study to patients, and the patients who voluntarily consented to participate were assessed for eligibility.
The inclusion criteria were as follows: 1) diagnosis of schizophrenia according to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5); 2) Pittsburgh Sleep Quality Index (PSQI-K) of ≥5, which is indicative of clinically significant sleep problems; and 3) age 18–65 years. The exclusion criteria were as follows: 1) Psychotic Symptom Rating Scale (PSYRATS) score >2 for either delusions or hallucinations; 2) hospitalization in closed wards for at least 3 months before study enrollment; 3) changes in psychiatric medication for at least the past month; and 4) diagnosis of sleep apnea, alcohol or substance use disorders, organic brain damage, or intellectual disability.
All patients included in the study completed the baseline (before sessions) and follow-up assessments (after sessions 2, 3, and 4) and were analyzed. Psychiatric evaluations were conducted by two psychiatrists who were also evaluators of the scales used in this study.

CBT-I

All participants received four sessions of individual or group CBT-I (Table 1). Each session was completed in groups; missed sessions were supplemented with individual sessions. Our CBT-I program was modified for patients with schizophrenia with relatively stable psychotic symptoms based on the clinical guidelines for insomnia in psychosis [21]. Each session lasted approximately 60 min, with some flexibility in the session duration. The patients were provided with a resource pack at each session that outlined the skills addressed in that session and a sleep diary.

Measures

The PSQI-K [22] and Insomnia Severity Index (ISI) [23] were used as the main outcomes to determine the effectiveness of CBT-I. The PSQI-K components include subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. These scores for these seven components were summed to yield the total PSQI-K. The ISI is a self-report questionnaire that measures the patients’ perceptions of insomnia; the index is scored as follows: 0 to 7 indicating “no clinically significant insomnia”; 8–14 indicating “subthreshold insomnia;” 15–21 indicating “moderate clinical insomnia;” and 22–28 indicating “severe clinical insomnia.” The Dysfunctional Beliefs and Attitudes about Sleep Scale-16 (DBAS-16) [24] was used to measure maladaptive cognition associated with sleep. This scale comprises the following four subscales: “consequences,” “worry/helplessness,” “expectations,” and “medication.” The Korean version of the Epworth Sleepiness Scale (K-ESS) [25] was used to evaluate the average sleep propensity in daily life. Total sleep time [26] and sleep onset latency [27] were also assessed from each sleep diary.

Statistical analysis

All statistical analyses were performed using the IBM SPSS 27 software (IBM Corp., Armonk, NY, USA). Continuous variables are reported as mean and standard deviation (SD) and categorical variables as frequency and percentage. As the primary results of this pilot study, the mean and standard deviation of all outcomes were calculated at the following timepoint: baseline before session 1 and after sessions 2, 3, and 4. The primary significance values for each outcome variable were calculated using one-way repeated measures analysis of variance (ANOVA), with the timepoint as a within-subjects factor. When ANOVA findings were significant, post-hoc comparison tests were performed to compare the data at baseline before session 1 and after sessions 2, 3, and 4. A p-value of <0.013, using the Bonferroni correction for multiple comparisons, was considered statistically significant. Partial eta-squared (η2) values were used when indicated to reflect the effect sizes; partial eta-squared represented a small effect size, while 0.06 denoted a medium effect size, and 0.14 indicated a large effect size, as established by previous research [28].

RESULTS

Study population

As shown in the study flowchart (Figure 1), 38 patients with schizophrenia who had difficulty in sleeping participated and were assessed for eligibility. Five patients were excluded for meeting the exclusion criteria and two were unable to participate in the CBT-I schedule. Finally, 31 patients received four weekly sessions of CBT-I; there were no dropouts during the treatment period. All 31 patients completed the baseline (before sessions) and follow-up assessments (after sessions 2, 3, and 4) and were analyzed.

Sample characteristics

The demographic and baseline clinical characteristics of the participants are presented in Table 2. The mean age of the participants (n=31; female: 54.8% [n=17]) was 46.97 years (SD=11.46). The mean body mass index was 24.55 kg/m2. The PSYRATS score was used to exclude insomnia symptoms caused by worsening psychotic symptoms, and the baseline total PSYRATS score was 3.57 (SD=3.84). The mean score on the auditory hallucination subscale was 3.32 (SD=3.69), and the mean score on the delusion subscale was 0.26 (SD=1.00). The mean baseline Patient Health Questionnaire-9 (PHQ-9) score was 4.06 (SD=3.79).

Acceptability and feasibility of CBT-I

The complete CBT-I program was completed by 31 (93.9%) patients who signed the consent form (n=33); the complete program included four treatment sessions and both pre- and posttreatment assessments.

Improvement in sleep problems

Compared with the baseline data, the mean total DBAS-16 score, ESS score, and ISI significantly decreased after sessions 2, 3, and 4. Table 3 presents the changes in the clinical outcomes of CBT-I over the study period. Repeated-measures ANOVA revealed a significant effect of time on DBAS-16 score [F(50.39); p<0.001], ESS score [F(33.85); p<0.001], and ISI [F(29.23); p<0.001]. The sleep onset latency from the sleep diary at each study timepoint showed a significant improvement over the period [F(29.70); p< 0.001]. Similarly, the mean total PSQI-K decreased significantly after sessions 2, 3, and 4. However, some scores of the PSQI-K subscales (sleep duration, use of sleep medication, and daytime dysfunction) showed no reliable improvement over this period. The total sleep time from the sleep diary also showed no significant improvement over the study period.

DISCUSSION

In this single-arm pilot study, we assessed the efficacy and feasibility of a four-session CBT-I program in patients with schizophrenia and comorbid insomnia. Our findings indicated that our CBT-I protocol for schizophrenia was highly acceptable and yielded improvements in insomnia symptoms over the treatment period.
The results of a previous preliminary study [16] and two randomized controlled studies [15,18] on CBT-I in patients with schizophrenia were consistent with those of our study regarding the improvement in ISI and PSQI after CBT-I.
Based on comparison with previous research, the present study has several clinical implications. First, this study took a unique approach by excluding patients who had undergone medication changes or hospitalization in the past month due to worsening psychotic symptoms using the PSYRATS, which differs from that in previous CBT-I studies targeting patients with schizophrenia. As mentioned above, there is a bidirectional relationship between psychological symptom exacerbations and insomnia. Therefore, a series of efforts were made in this study to exclude patients with insomnia due to worsening psychological symptoms and to target a group of patients that is more suitable for cognitive-behavioral treatment with the goal of correcting the perpetuating factors in the 3P model of insomnia [29]. Given that CBT-I targets the factors that perpetuate insomnia’s transition from acute to chronic state [30], our study design was more suitable to show its efficacy in improving insomnia in patients with schizophrenia.
Second, this study assessed cognitive changes using the DBAS-16, revealing a significant reduction in cognitive misperception. This aligns with the impact of CBT-I on cognitive aspects seen in primary insomnia [31]. Considering that cognitive impairment is a critical factor when implementing CBT-I for patients with schizophrenia, there may exist limitations to CBT use in patients with schizophrenia [1]. Nevertheless, previous CBT-I studies have demonstrated cognitive changes among patients with schizophrenia [32,33]. Nighttime rumination, which is notably prevalent among patients with schizophrenia [32], triggers emotional arousal and conditioning that can perpetuate insomnia [34]. Therefore, we aimed to provide cognitive interventions to assist in managing overly negative thoughts, including unhelpful beliefs and attitudes about sleep and cognitive hyperarousal, and these interventions were effective.
Third, our treatment helped in improving sleep/wake homeostasis and maintaining circadian rhythms, thereby reducing daytime sleepiness and improving sleep-onset latency. This observed reduction in daytime sleepiness aligns with previous research indicating disturbances in sleep and circadian rhythms among individuals with schizophrenia [9]. In patients with schizophrenia, diminished daytime activity attributable to negative symptoms like avolition can disturb the circadian rhythm, subsequently contributing to the onset of insomnia [35]. Antipsychotic drugs, which are mainly used in patients with schizophrenia, can also cause sedation. Therefore, reducing daytime sleepiness in patients with schizophrenia and insomnia is an important factor in improving their quality of life [36].
Interestingly, we found no significant changes in the total sleep time or sleep duration subscales of the PSQI-K in this study. Regarding changes in the total sleep time after treatment for primary insomnia [37] and secondary insomnia in psychiatric medical conditions [38], studies have reported only small improvements or no changes. In the present study, the baseline total sleep time from the sleep diary was 497.74 min on weekdays and 519.67 min on weekends. These patients have been classified in previous studies as experiencing “insomnia with normal sleep duration” [26], suggesting characteristic low sleep efficiency and low sleep onset latency. Consequently, the recommended focus for these patients lies in reducing daytime dysfunction and improving sleep efficiency [17].
This study also has several limitations. First, it was a single-arm pilot study with no control group; therefore, it is challenging to conclusively demonstrate the efficacy of CBT-I. The small sample size of this pilot study was another limitation of the study. However, these data can be used to inform future large-scale randomized controlled trials to precisely evaluate the efficacy of CBT-I in patients with schizophrenia who have insomnia symptoms. Second, our study was conducted at a single hospital; therefore, the results should be interpreted with caution, as they may not be applicable to different settings. However, our study was conducted by only two psychiatrists at one hospital, and it provides consistent standards for CBT-I and clinical assessment. Third, some measurements were subjective; therefore, these data may have been influenced by a response bias. Other studies have obtained objective outcomes using actigraphy or polysomnography data [39]. We also consider it important to increase compliance with CBT-I and reduce the dropout rate. Further methodologies must be considered to obtain objective data for larger randomized trials.
In conclusion, our data suggest that CBT-I is highly effective in improving both cognitive and behavioral sleep difficulties in patients with schizophrenia without prior psychotic aggravation. This study suggests that unless insomnia in patients with schizophrenia is caused by apparent psychotic symptom exacerbation, providing appropriate CBT-I prior to pharmacotherapy can help improve patient compliance and insomnia symptoms. To clarify these results, it is necessary to plan a larger randomized controlled trial that addresses these limitations.

NOTES

Funding Statement

None

Conflicts of Interest

The authors have no potential conflicts of interest to disclose.

Availability of Data and Material

The datasets generated or analyzed during the study are available from the corresponding author upon reasonable request.

Author Contributions

Conceptualization: Yujin Lee. Data curation: Ji Seok Kim, Yujin Lee. Formal analysis: Ji Seok Kim, Yujin Lee. Investigation: Ji Seok Kim, Yujin Lee. Methodology: Ji Seok Kim, Yujin Lee. Project administration: Ji Seok Kim, Yujin Lee. Supervision: Yujin Lee. Writing—original draft: Ji Seok Kim. Writing—review & editing: Yujin Lee.

Figure 1.
Study flowchart for patients with schizophrenia included in this study. CBT-I: cognitive behavioral therapy for insomnia.
cim-2023-0024f1.jpg
Table 1.
Course of CBT-I program
Session number Components of session
Session 1 Psychoeducation Formulation and goal setting
Sleep hygiene
Stimulus control
Establishment of wind-down and regular rising time
Session 2 Maximizing daytime energy Sleep diary check and discussion
Managing unhelpful beliefs about sleep Motivation boost
Brief relaxation exercises
Session 3 Strategies to reduce impact of negative emotions
Strategies to reduce impact of hallucination and intrusive thoughts
Brief relaxation exercises
Session 4 Sleep review
Relapse prevention planning

CBT-I, cognitive behavioral therapy for insomnia

Table 2.
Sample demographics and baseline clinical characteristics of all study participants (n=31)
Characteristics Value
Age (yr) 46.97±11.46
Sex
 Female 17 (54.8)
 Male 14 (45.2)
Marital status
 Married or partnered 24 (77.4)
Education (yr) 12.5±1.46
Job status
 Employed 10 (32.3)
 Unemployed 21 (67.7)
BMI (kg/m2) 24.55±4.21
PSYRATS, total mean score 3.57±3.84
 PSYRATS, auditory hallucinations 3.32±3.69
 PSYRATS, delusions 0.26±1.00
PHQ-9 score 4.06±3.79

Values are presented as mean±standard deviation or n (%). BMI, body mass index; PSYRATS, Psychotic Symptom Rating Scale; PHQ-9, Patient Health Questionnaire-9

Table 3.
Changes in clinical outcomes following cognitive behavioral therapy for insomnia (n=31)
Baseline (a) After session 2 (b) After session 3 (c) After session 4 (d) F (p value) Post-hoc analysis Effect size
DBAS-16, total 110.77 (28.07) 92.80 (29.44) 81.96 (22.10) 60.87 (25.24) 50.39 (<0.001) a>b>c>d 0.627
Expectations subscale 15.13 (4.36) 13.48 (4.72) 11.19 (3.30) 9.48 (4.11) 21.23 (<0.001) a, b>c, d 0.414
Worry/helplessness subscale 40.35 (11.92) 35.70 (12.16) 28.5 (8.85) 22.51 (9.63) 36.69 (<0.001) a>b>c>d 0.550
Consequences subscale 35 (10.54) 30.61 (10.51) 22.75 (8.14) 18.83 (8.38) 42.47 (<0.001) a>b>c>d 0.586
Medication subscale 20.29 (6.03) 17.83 (5.80) 14.25 (4.37) 10.03 (5.10) 43.80 (<0.001) a>b>c>d 0.594
ESS 9.16 (4.71) 8.09 (4.42) 6.45 (3.85) 4.25 (3.51) 33.85 (<0.001) a>b>c>d 0.530
ISI 11.80 (6.67) 10.06 (5.53) 7.93 (4.18) 5.51 (3.94) 29.23 (<0.001) a>b>c>d 0.494
PSQI-K 8.77 (2.20) 8.25 (2.46) 6.45 (2.77) 4.45 (1.93) 46.25 (<0.001) a,b>c,d 0.607
Subjective sleep quality 1.83 (0.78) 1.61 (0.72) 1.45 (0.62) 0.96 (0.41) 24.82 (<0.001) a>b,c>d 0.453
Sleep latency 2.25 (0.73) 1.74 (0.86) 1.25 (0.78) 0.87 (0.62) 32.58 (<0.001) a>b,c>d 0.521
Sleep duration 0.26 (0.51) 0.32 (0.54) 0.19 (0.40) 0.16 (0.37) 1.84 (0.159) n/a 0.058
Habitual sleep efficiency 1.00 (0.82) 0.54 (0.72) 0.19 (0.48) 0.06 (0.25) 24.27 (<0.001) a>b, c>d 0.447
Sleep disturbance 1.58 (0.62) 1.51 (0.63) 1.12 (0.43) 1.06 (0.36) 11.70 (<0.001) a, b>c, d 0.281
Use of sleep medication 1.13 (1.14) 1.23 (0.97) 1.20 (0.98) 0.7 (0.88) 3.39 (<0.076) n/a 0.104
Daytime dysfunction 0.68 (0.95) 1.26 (0.86) 1.03 (0.75) 0.65 (0.49) 7.13 (<0.001) b, c>a, d 0.192
Total sleep time
Weekday (min) 497.74 497.74 516.12 499.83 1.46 (0.237) n/a 0.046
Weekend (min) 519.67 521.61 530.32 515.96 0.893 (0.434) n/a 0.029
Sleep onset latency (min) 56.83 42.09 35.80 24.19 29.70 (<0.001) a>b, c>d 0.498

Values are presented as mean (standard deviation) or mean value only. All p-values for effect of timepoint are according to one-way repeated ANOVA. DBAS-16, Dysfunctional Beliefs and Attitudes about Sleep Scale-16; ESS, Epworth Sleepiness Scale; ISI, Insomnia Severity Index; PSQI-K, Korean version of the Pittsburgh Sleep Quality Index

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