imConsultation Request Types and Clinical Implications for Insomnia in Inpatients: A Comparative Study With Anxiety and Depressive Disorders
Article information
Abstract
Objective
Insomnia is one of the most common psychiatric symptoms among inpatients, frequently accompanied by sleep–wake and circadian disruption and showing distinct consultation patterns. This study aimed to examine the consultation request patterns and clinical implications of insomnia in hospitalized patients, and to compare them with those of patients with anxiety and depressive disorders.
Methods
A retrospective chart review was conducted for 1,286 patients who received psychiatric consultations at a general hospital between 2005 and 2011. The sample included 236 patients with insomnia, 601 with anxiety disorders, and 449 with depressive disorders based on DSM-IV-TR criteria. Demographic characteristics, referring departments, reconsultation status, number of consultations, and consultation request types (CR1–CR5, based on the Vaz-Salcedo functional model) were analyzed.
Results
Patients with insomnia were especially older and had a higher proportion of males compared with the other diagnostic groups. The insomnia group showed the lowest mean number of consultations and the lowest reconsultation rate. More than half of consultation requests for insomnia patients were classified as CR3 (Mending type), a proportion more than twice that observed in the anxiety disorder group. After adjustment for age and sex, insomnia remained independently associated with a significantly higher likelihood of CR3 consultation requests.
Conclusion
Insomnia in hospitalized patients exhibits distinct consultation-liaison patterns, with a predominance of CR3, indicating a largely symptom-oriented management approach. Future multicenter, prospective studies with longitudinal follow-up are needed to evaluate the effectiveness of pharmacological and non-pharmacological interventions and to clarify the impact of early insomnia-focused psychiatric consultation on long-term clinical outcomes.
INTRODUCTION
Insomnia is recognized as one of the most prevalent and clinically significant psychiatric complaints among patients hospitalized in general medical and surgical wards. In contrast to community-based insomnia, inpatient sleep disturbances are often acute and multifaceted [1]. These disturbances are closely linked to the underlying physical illness, the stress of the hospital environment, and the physiological effects of medical interventions [2]. While transient sleep loss might seem secondary to the primary reason for admission, persistent insomnia can lead to imCIMpaired immune function, delayed wound healing, and an increased risk of cardiovascular complications, thereby prolonging hospital stays and escalating healthcare costs [3,4]. Despite its clinical importance, insomnia in the general hospital setting is frequently managed as a transient symptom rather than a distinct disorder requiring comprehensive psychiatric evaluation, often leading to a reliance on symptom-focused management [5,6]. In addition, hospitalization itself is associated with substantial disruption of the sleep–wake cycle, including altered light–dark exposure, nocturnal nursing care, and irregular timing of medications, all of which can lead to circadian misalignment. Such circadian disrup tion may contribute to the acute and symptom-oriented presentation of insomnia observed in hospitalized patients.
The demographic profile of inpatients referred for psychiatric consultation for insomnia shows distinct characteristics that differ from those referred for anxiety or depression. Historically, mood and anxiety disorders have shown a higher prevalence among younger female populations [7,8]. However, inpatient insomnia is more frequently observed in the elderly, a demographic that is increasingly represented in general hospital populations due to global aging trends [9]. Aging is associated with significant alterations in sleep architecture, including decreased slow-wave sleep and increased sleep fragmentation, making older adults more vulnerable to environmental disruptions such as nocturnal noise, and frequent nursing interventions, as well as medicationrelated sleep disturbances associated with polypharmacy [10,11]. Furthermore, in geriatric patients, insomnia is a well-documented risk factor for the development of delirium, which further complicates the clinical course and increases mortality rates [12,13].
The nature of psychiatric consultation requests (CR) often reflects the referring physician’s perception of the psychiatrist’s role. Vaz and Salcedo [14] proposed a functional model of consultation-liaison psychiatry, classifying requests into five categories (CR1–CR5) based on the primary clinical objective. Among these, CR3 (Mending type) represents requests for immediate symptomatic relief for acute behavioral or emotional distress [15]. In surgical departments, where the incidence of acute pain and postoperative stress is high, insomnia consultations are frequently initiated to manage immediate sleep-wake disturbances that interfere with post-operative recovery [16]. This contrasts with internal medicine, where consultations may involve more complex diagnostic clarification or the management of chronic psychiatric comorbidities [17,18]. Understanding whether insomnia is being treated as a “mending” issue rather than a “parallel” or “complementary” management issue is crucial for defining the psychiatrist’s role in a multidisciplinary team [19].
Despite the high volume of sleep-related consultations, there is a paucity of large-scale comparative research that systematically evaluates how insomnia consultations differ from those for other common psychiatric conditions like anxiety and depression within the same hospital ecosystem. Most studies focus on pharmacological efficacy or the prevalence of sleep disorders in specific medical populations, leaving a gap in our understanding of the liaison process itself [20,21]. Therefore, this study aims to analyze the consultation patterns of 1,286 inpatients over a 7-year period (2005–2011), utilizing the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) framework, which was the diagnostic standard at the time, and the functional CR model. By examining demographic variables, referring departments, and reconsultation rates, we seek to elucidate the unique clinical trajectory of insomnia. We hypothesize that insomnia consultations will be characterized by a higher mean age, a distinct sex distribution, and a significantly higher proportion of CR3 (mending) requests. This pattern would reflect a clinical demand for rapid, symptom-oriented intervention in the acute hospital setting [22,23]. From a chronobiological perspective, understanding how insomnia is managed in the acute hospital environment may provide important insights into the interaction between circadian disruption, medical illness, and clinical decision-making.
METHODS
Study population and data collection
This study is a retrospective observational analysis of inpatients who received psychiatric consultations at a general center in Seoul, South Korea. Data were extracted from the institution’s electronic medical record system, covering an exhaustive review of 1,286 initial psychiatric consultation requests over a 7-year period (2005–2011). This sample size was based on all eligible cases during the study period who met the inclusion criteria.
The study population was restricted to adult inpatients whose final psychiatric diagnoses were confirmed as insomnia (n=236), anxiety disorders (n=601), or depressive disorders (n=449). To ensure diagnostic homogeneity and the validity of the results, the following inclusion and exclusion criteria were applied:
Inclusion criteria were as follows : 1) the first psychiatric consultation occurring within the study period; 2) a clearly documented psychiatric diagnosis based on DSM-IV-TR criteria at the time of consultation; and 3) complete availability of key clinicodemographic variables, including age, sex, referring department, number of consultations, reconsultation status, and consultationrequest type. Diagnostic group assignment was based exclusively on the final psychiatric diagnosis documented in the official consultation record according to DSM-IV-TR criteria, rather than on the wording of the referral request or chief complaint. Reconsultation was defined as cases in which two or more psychiatric consultations were conducted for the same patient.
Exclusion criteria were: 1) cases with comorbid psychiatric diagnoses whose primary diagnoses could not be clearly determined; 2) incomplete consultation records or missing documentation of CR type; and 3) patients under 18 or over 85 years of age. Patients aged over 85 years were excluded to minimize clinical heterogeneity associated with extreme old age, including a higher prevalence of cognitive impairment and delirium, which could confound consultation patterns.
The study protocol was approved by the Institutional Review Board (IRB) of Konkuk University Medical Center (Approval No. 2026-01-052) and was conducted in strict accordance with the ethical principles of the Declaration of Helsinki. Given the retrospective nature of the chart review, the requirement for individual informed consent was waived, and all personal identifiers were anonymized to ensure patient confidentiality.
Classification of consultation-liaison referral pathways
Consultation referral pathways were classified using the functional model proposed by Vaz and Salcedo (1996) [14]. This framework categorizes the role of psychiatric intervention based on the timing of symptom onset and its relationship with the primary medical condition as follows:
- Complementary (CR1): Cases where psychiatric care complements or supports the primary treatment of the patient’s physical illness.
- Parallel (CR2): Cases requiring management of pre-existing psychiatric disorders that are independent of the current reason for hospitalization.
- Mending (CR3): Cases where acute psychiatric symptoms emerge after admission, requiring immediate symptomatic relief and short-term intervention.
- Antecedent-conditioned (CR4): Referrals prompted by a known history of psychiatric illness rather than current acute symptoms.
- Misdiagnosis-conditioned (CR5): Cases where non-psychiatric (somatic) symptoms were mistakenly attributed to psychiatric causes by the referring physician.
The classification of CR types was initially performed by a psychiatry resident and subsequently reviewed and finalized through discussion with a board-certified psychiatrist to ensure diagnostic consistency.
Statistical analysis
Statistical analyses were performed using SPSS version 27.0 (IBM Corp.). Descriptive statistics were utilized to summarize clinico-demographic characteristics, with continuous variables expressed as mean±standard deviation and categorical variables as frequencies and percentages.
To examine differences across the three diagnostic groups, one-way analysis of variance (ANOVA) followed by Tukey’s post-hoc tests was applied for continuous variables such as age and the number of consultations. Categorical variables, including sex, referring department, reconsultation status, and CR types, were compared using the chi-square (χ2) test. Effect sizes were calculated and reported as appropriate (eta-squared for ANOVA, Cramer’s V for chi-square tests).
To identify independent predictors of the Mending (CR3) pathway specifically for insomnia patients, a multivariable logistic regression analysis was conducted, adjusting for potential confounders such as age and sex. The results are presented as adjusted odds ratios (OR) with 95% confidence intervals (CI). Model fit was verified using the Hosmer-Lemeshow test. All statistical tests were two-tailed, and a p-value less than 0.05 was considered statistically significant.
RESULTS
Demographic and clinical characteristics
A total of 1,286 patients were included in the final analysis: 236 in the insomnia group (18.4%), 601 in the anxiety disorder group (46.7%), and 449 in the depressive disorder group (34.9%). Significant age variations were observed among the three groups (F=25.10, p<0.001) (Table 1). The insomnia group had the highest mean age (61.96±14.26 years), followed by the depressive disorder group (59.02±16.93 years), while the anxiety disorder group was the youngest (53.40±19.04 years). Patients in the insomnia group were significantly older on average than those in the other two groups (p<0.001). Post-hoc analysis confirmed that the age differences between the insomnia and anxiety groups, as well as between the depressive disorder and anxiety groups, were statistically significant (p<0.001). Regarding sex distribution, the insomnia group had the highest proportion of males (54.7%), whereas females predominated in the anxiety (63.6%) and depressive disorder (68.4%) groups (χ2=36.13, p<0.001) (Figure 1). These findings underscore that inpatient insomnia, as defined by DSM-IVTR criteria, is more frequently observed in older male inpatients.
Demographic and consultation characteristics of patients diagnosed with insomnia, anxiety disorder, and depressive disorder
Clinical and consultation profiles by diagnostic group. Comparison of sex distribution, referring department (internal vs. surgical), reconsultation status, and mean number of psychiatric consultations across insomnia, anxiety, and depressive disorder groups. The insomnia group showed a higher proportion of males and lower consultation intensity compared with the other groups (all p<0.001).
Referring department and consultation intensity
When classified by referring department, the insomnia group had the lowest proportion of referrals from internal medicine (53.0%) and a relatively higher proportion from surgical specialties (47.0%). In contrast, internal medicine was the primary source of referrals for both anxiety (64.1%) and depressive disorders (69.3%) (χ2=17.83, p<0.001) (Table 1).
Consultation intensity was notably lower for insomnia patients (Figure 1). The reconsultation rate was lowest in the insomnia group (27.5%), compared with 39.1% for anxiety and 48.6% for depression (χ2=29.04, p<0.001). Similarly, the mean number of consultations was lowest for insomnia (1.54±1.49), followed by anxiety (1.81±1.48) and depression (2.09±1.81) (F=15.47, p<0.001) (Table 1). These findings imply that inpatient insomnia consultations are more likely to be brief and focused on immediate symp-tom management, whereas anxiety and depressive disorders are associated with greater consultation intensity and continuity of psychiatric care.
Consultation request types
The distribution of CR types (CR1–CR5) differed significantly across groups (χ2=91.87, p<0.001) (Table 2). In the insomnia group, CR3 (mending request) was predominant, accounting for more than half of all cases (51.3%) (Figure 2). This was significantly higher than the proportions observed in the anxiety disorder group (24.5%) and the depressive disorder group (36.7%). In the anxiety disorder group, CR1 (29.3%) and CR2 (33.6%) were the predominant request types, whereas in the depressive disorder group, CR2 (36.7%) and CR3 (36.7%) were nearly equally represented. CR4 was relatively more frequent in the anxiety disorder group (12.5%) but uncommon in both the insomnia and depressive disorder groups. CR5 was rare across all groups.
Distribution of consultation request types among patients with insomnia, anxiety disorder, and depressive disorder
Distribution of consultation request (CR) types across diagnostic groups. Percentage distribution of CR1–CR5 categories among insomnia, anxiety, and depressive disorder groups. The insomnia group demonstrated a predominance of CR3 (Mendingtype) requests, with significant between-group differences (p<0.001). Logistic regression analysis confirmed an independent association between insomnia and CR3 requests after adjustment for age and sex.
In a multivariable logistic regression analysis adjusted for age and sex, the insomnia group remained independently associated with a significantly higher likelihood of CR3 requests compared to the other groups (adjusted OR=2.41, 95% CI=1.65–3.52, p< 0.001) (Figure 2). These results indicate that psychiatric consultations for insomnia are primarily focused on immediate symptomatic relief for conditions such as acute sleep disturbance or pain-related insomnia rather than comprehensive or long-term intervention. In contrast, consultation requests for anxiety and depressive disorders more frequently reflected the need for diagnostic clarification or parallel psychiatric management of pre-existing conditions, rather than solely addressing acute symptoms.
DISCUSSION
This study compared consultation-liaison psychiatry referral patterns among inpatients with insomnia, anxiety disorders, and depressive disorders, demonstrating that inpatients referred for insomnia exhibit distinct demographic characteristics and consultation patterns compared to those with anxiety or depressive disorders. The insomnia group had the highest mean age (61.96 years), reflecting the vulnerability of elderly patients to sleep architecture changes and the hospital environment [24,25]. As patients age, slow-wave sleep decreases and sleep fragmentation increases, making them more sensitive to environmental factors such as ward noise and nocturnal nursing care [26].
Regarding the types of consultation requests, over half of the insomnia patients (51.3%) were classified as the “Mending type (CR3).” This contrasts sharply with anxiety or depressive disorders, which are often referred for long-term psychiatric management (CR2) or diagnostic clarification (CR1) [27]. The overwhelming prevalence of the Mending type suggests that referring physicians often view insomnia as a transient symptom caused by environmental changes, physical pain, or postoperative stress rather than a chronic psychiatric disorder [28,29]. Consequently, insomnia consultations are primarily oriented toward immediate symptomatic relief, diverging from the more longitudinal psychiatric interventions observed in anxiety or depressive disorders.
Our findings also revealed that the insomnia group had a higher proportion of males (54.7%) and a relatively higher rate of referrals from surgical departments compared to other diagnostic groups. While insomnia in the general community is typically more prevalent in females, the inpatient data likely reflects the high volume of male patients experiencing acute pain or postoperative stress in surgical wards [25,30]. Surgical patients, in particular, frequently experience sleep-wake cycle disturbances due to acute pain and mobility restrictions, which can subsequently impair immune function and delay wound healing [31]. This high prevalence in surgical settings aligns with the predominance of CR3 requests, as surgeons often prioritize rapid recovery of the sleep-wake cycle over long-term psychiatric management.
In terms of consultation intensity, the insomnia group showed the lowest reconsultation rate (27.5%) and the lowest mean number of consultations (1.54). This further confirms that insomnia consultations are predominantly focused on short-term pharmacological intervention and acute symptom control [32]. However, considering that chronic insomnia increases the risk of cardiovascular complications and elevates healthcare costs, liaison psychiatry should integrate long-term strategies such as Cognitive Behavioral Therapy for Insomnia (CBT-I) and sleep hygiene education into the standard care for these patients [29,30]. To move beyond simple “mending” interventions, hospitals may benefit from implementing these structured protocols, including brief-format interventions and standardized sleep hygiene education tailored for the ward environment.
Limitation
This study contributes meaningfully by systematically characterizing CR types among inpatients with insomnia and identifying distinctive patterns associated with this group. In particular, applying the classification proposed by Vaz and Salcedo [14] to real-world clinical data allowed us to delineate the specific consultation characteristics associated with insomnia. Nevertheless, several limitations should be noted. First, the study was conducted retrospectively at a single institution, limiting generalizability to broader inpatient populations with insomnia, anxiety, or depression. In addition, this study included only patients who were referred for psychiatric consultation, which may introduce selection or referral bias, as consultation requests are influenced by clinicians’ perceptions, departmental practices, and institutional culture. Additionally, the study did not assess how consultation patterns influenced clinical outcomes. Future studies employing multicenter, prospective designs are needed to examine the impact of insomnia-related consultations on outcomes such as length of stay, readmission rates, and symptom improvement. Second, rare consultation types (e.g., CR4, CR5) were underrepresented, constraining interpretability. Furthermore, although analyses were adjusted for age and sex, other potentially important confounding factors—such as severity of medical illness, pain intensity, delirium risk, medication use, and ward characteristics—were not systematically controlled for, which may have influenced consultation patterns. Third, insomnia was analyzed as a single diagnostic entity, limiting our ability to consider the complex interplay between insomnia and co-occurring anxiety or depressive symptoms. Longitudinal research is warranted to determine whether CR3-dominant referral patterns effectively prevent or detect progression to anxiety or depression and whether early psychiatric intervention enhances long-term outcomes. Experimental studies examining the role of non-pharmacological strategies and multidisciplinary care models are also needed. Finally, the dataset reflects consultation practices from 2005 to 2011 and may not fully represent current patterns shaped by contemporary developments such as digitalized inpatient environments, expanded multidisciplinary consultation systems, and increased incorporation of non-pharmacological sleep interventions (e.g., CBT-I, environmental light adjustments). Future studies should replicate this analysis in modern clinical environments to evaluate temporal changes and ensure contemporary relevance.
Conclusion
This study demonstrated that inpatients with insomnia exhibit consultation request patterns distinct from those of patients with anxiety or depressive disorders. Notably, the predominance of Mending-type (CR3) consultation requests suggests that insomnia in the hospital setting is frequently managed with an acute, symptom-oriented approach, influenced by environmental disruption during hospitalization, physical conditions, and clinical perceptions that regard insomnia as a secondary symptom. However, reliance on CR3-focused management alone may overlook longer-term clinical risks and unmet therapeutic needs. Accordingly, multidimensional strategies—including early psychiatric involvement, environmental modification, sleep hygiene education, and appropriate pharmacological management—should be considered in routine inpatient care. Future multicenter, prospective studies with longitudinal follow-up are warranted to evaluate the effectiveness of both pharmacological and non-pharmacological interventions and to clarify how early, insomnia-focused psychiatric consultation influences long-term outcomes such as delirium, symptom persistence, readmission, and overall clinical trajectory.
Notes
Doo-Heum Park who is on the editorial board of Chronobiology in Medicine was not involved in the editorial evaluation or decision to publish this article. All remaining authors have declared no conflicts of interest.
Availability of Data and Material
The datasets generated or analyzed during the study are available from the corresponding author on reasonable request.
Author Contributions
Conceptualization: Min-Wung Cho, Doo-Heum Park. Data curation: Min-Wung Cho, Sumin Hong. Formal analysis: Min-Wung Cho. Methodology: Seung-Ho Ryu, Jee Hyun Ha. Supervision: Doo-Heum Park. Writing—original draft: Min-Wung Cho. Writing—review & editing: Hong Jun Jeon, Doo-Heum Park.
Funding Statement
None
Acknowledgments
The authors thank the medical records department of Konkuk University Medical Center for assistance with data retrieval.