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Volume 14 No. 02
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Accepted Papers

Scientific Investigations

Evaluating DSM-5 Insomnia Disorder and the Treatment of Sleep Problems in a Psychiatric Population

Lee Seng Esmond Seow, BA1; Swapna Kamal Verma, MBBS, MD2; Yee Ming Mok, MB BCh BAO, DIP, MMed2; Sunita Kumar, MD, FCCP, FAASM3; Sherilyn Chang, BSocSc1; Pratika Satghare, MSc, CRRA1; Aditi Hombali, MPT1; Janhavi Vaingankar, MSc1; Siow Ann Chong, MBBS, MMed, MD1; Mythily Subramaniam, MBBS, MHSM, PhD1
1Research Division, Institute of Mental Health, Singapore; 2Department of General Psychiatry, Institute of Mental Health, Singapore; 3Division of Pulmonary and Critical Care Medicine, Loyola University, Chicago, Illinois


Study Objectives:

With the introduction of insomnia disorder in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), greater emphasis has been placed on the diagnosis and treatment of sleep disorder even in the presence of a coexisting mental disorder. The current study seeks to explore the clinical picture of insomnia in the context of psychiatric disorders commonly associated with sleep complaints by assessing the prevalence and correlates of DSM-5 insomnia disorder, and examining the extent to which insomnia symptoms have been addressed in this population.


Four hundred treatment-seeking outpatients suffering from depressive, bipolar affective, anxiety, and schizophrenia spectrum disorders were recruited. DSM-5 insomnia was established using the modified Brief Insomnia Questionnaire. Differences in sociodemographic factors, clinical status, impairment outcomes, and mental health services utilization were compared. Information on patients' help-seeking experiences for insomnia-related symptoms was collected to determine the treatment received and treatment effectiveness.


Almost one-third of our sample (31.8%) had DSM-5 insomnia disorder. Those with insomnia disorder had significantly higher impairment outcomes than their counterparts but no group difference was observed for mental health services utilization. Findings based on past treatment contact for sleep problems suggest that diagnosis and treatment of insomnia is lacking in this population.


With the new calling from DSM-5, clinicians treating psychiatric patients should view insomnia less as a symptom of their mental illnesses and treat clinical insomnia as a primary disorder. Patients should also be educated on the importance of reporting and treating their sleep complaints. Nonmedical (cognitive and behavioral) interventions for insomnia need to be further explored given their proven clinical effectiveness.


Seow LSE, Verma SK, Mok YM, Kumar S, Chang S, Satghare P, Hombali A, Vaingankar J, Chong SA, Subramaniam M. Evaluating DSM-5 insomnia disorder and the treatment of sleep problems in a psychiatric population. J Clin Sleep Med. 2018;14(2):237–244.


Current Knowledge/Study Rationale: The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition distinction into primary and secondary insomnia has been replaced with a unitary diagnosis of insomnia disorder in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), an advocate for its detection and treatment even in the presence of comorbid mental disorders. In view of these changes, the current study aimed to determine the prevalence and correlates of DSM-5 insomnia disorder, and the extent of insomnia management and treatment in a psychiatric population.

Study Impact: Beyond mere symptoms of mental illnesses, our study illustrates that a high proportion of psychiatric patients also suffer from clinically significant insomnia disorder. Evidence from our study is indicative of the need for both clinicians and patients to place greater emphasis on addressing insomnia symptoms in this population.


Insomnia is a common sleep problem and is marked by the difficulty in initiating or maintaining sleep or when the sleep that is obtained is nonrefreshing or of poor quality.1 Research in insomnia has been undertaken in different populations and settings, including primary care, outpatient clinics, and the general population. Of these, chronic sleep problems have been most commonly reported among those with psychiatric disorders. Approximately 50% to 80% of adult patients with mental illnesses had difficulty with falling or staying asleep in a typical year.2 Research has shown that insomnia is strongly associated with psychiatric disorders and it can be primary or secondary to a mental disorder. The relationship between sleep and mental disorders has been described as complex and is possibly marked by bidirectional causality.3 Data from the large-scale Epidemiologic Catchment Area project revealed that 40% of insomnia sufferers meet criteria for at least one psychiatric disorder, with 23% of them also receiving a diagnosis of major depression or dysthymia; 24%, anxiety disorders; 7%, alcohol abuse; and 4%, drug abuse.4 Evidence supporting this interrelationship has found that treating certain psychiatric conditions may help to improve sleep and treating sleep disturbances can have a beneficial effect on their psychiatric treatment.3

Few psychiatric disorders have been consistently identified in the sleep literature due to their strong associations with insomnia—major depressive disorder (MDD), bipolar disorder, anxiety disorders, and schizophrenia spectrum disorder.3,58 Depression is by far the most extensively studied in terms of sleep disturbance with more than 90% of individuals with MDD having reported insomnia-related sleep disturbance.9,10 Insomnia has been recognized as a core symptom of depression.11 In bipolar disorder, the diagnostic criteria indicate that there may be a decreased need for sleep during the manic phase and a decreased inability to sleep during the depression phase with about 69% to 99% of the patients being affected.12 Insomnia is also prevalent among those with anxiety disorders, particularly among those with generalized anxiety disorder and posttraumatic stress disorder given that sleep disturbance has been identified as a diagnostic criterion for these disorders.13,14 Lastly, sleep difficulties have been frequently reported among those with schizophrenia, possibly secondary to the hyperarousal caused by positive psychotic symptoms,15 and approximately 40% of an outpatient sample was found to meet the criteria for clinical insomnia.16 In Singapore, the lifetime prevalence of MDD, bipolar disorders, and anxiety disorders was 5.8%, 1.2%, and 3.6%, respectively,17 whereas the lifetime prevalence of any psychotic experience was 3.8%18 based on findings from the Singapore Mental Health Study.

The presence of insomnia symptoms can have adverse implications on sufferers in terms of their emotional and mental health and quality of life. Daytime consequences include increased risks of accidents, decreased work productivity and concentration, and impaired daily performance.19,20 Among individuals with mental disorders, the presence of sleep disturbance independent of the patients' primary condition was also associated with higher symptom severity, higher disorder severity, lower level of functioning, and fewer benefits from treatment.21 The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) calls for the independent clinical importance of a sleep disorder regardless of the presence of a coexisting mental or medical condition. As a result, the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition distinction into primary and secondary insomnia has been removed in DSM-5 and replaced with the diagnosis of insomnia disorder in favor of unitary diagnosis of insomnia disorder with concurrent specification of clinically comorbid conditions. This significant change in the sleep-wake diagnostic criteria in recognition of the comorbid nature of insomnia also advocates for the treatment of insomnia itself in addition to the medical or psychiatric disorder.22

The current study therefore aims to provide an overview of the clinical picture of insomnia in view of the new highlights in DSM-5 among a group of psychiatric patients with major depressive, bipolar affective, anxiety, and schizophrenia spectrum disorders. Mainly, we intend to establish the prevalence of clinical insomnia using DSM-5 diagnostic criteria along with its correlates, and to evaluate the extent to which sleep problems were treated in this patient population.


Study Participants

This cross-sectional study recruited adult patients who were seeking treatment at the outpatient and community-based clinics of the Institute of Mental Health, the main psychiatric hospital in Singapore. Inclusion criteria included age of 21 to 65 years and the ability to complete self-administered study questionnaires; exclusion criteria included history of intellectual disability or dementia. Study subjects were recruited using multiple methods (posters and flyers) and referral sources (psychiatrists, other health care professionals, or self-referral). A total of 400 psychiatric outpatients were recruited based on their primary diagnosis—100 with major depressive disorder, 80 with bipolar affective disorder, 100 with anxiety disorders, and 120 with schizophrenia spectrum disorder (schizophrenia or schizoaffective disorder). All psychiatric diagnoses were made by the attending psychiatrists based on International Classification of Diseases, 9th Revision criteria. Written informed consent was obtained from all participants. The study was approved by the ethics committee of the Domain Specific Review Board of the National Healthcare Group, Singapore and participants were reimbursed upon completion of the questionnaires.

Data Collection

Participants were asked to complete a questionnaire set comprising sociodemographic (age, sex, ethnicity, marital status, education, and employment) and lifestyle information (smoking, drinking, and physical activity statuses). For physical activity level, participants were first asked to recall the number of days in an average week and for how long each day they had engaged in activities that increased their heart rate and/or made them breathe hard before providing an overall rating. All clinical information including psychiatric and medical diagnoses, psychiatric illness duration and onset, use of sleep medication, and mental health services utilization (hospitalization, outpatient, emergency, and psychologist visits) in the past year was obtained from the patients' medical records. For the purpose of this study, medications for sleep problems included diazepam, lorazepam, alprazolam (Xanax), zolpidem tartrate, zopiclone and hydroxyzine (Atarax). The participants were also required to self-complete a set of questionnaires (described in the following paragraphs) to measure their impairment outcomes due to sleep, followed by a structured interview—the modified Brief Insomnia Questionnaire (BIQ) to determine their status for DSM-5 insomnia disorder.


Brief Insomnia Questionnaire

The BIQ is a fully structured questionnaire first developed to diagnose insomnia according to hierarchy-free Diagnostic and Statistical Manual, Fourth Edition, Text Revision, International Classification of Diseases, Tenth Revision, and research diagnostic criteria/International Classification of Sleep Disorders, Second Edition general criteria without organic exclusions.23 Additional items were later added and validated in the Hong Kong population to generate insomnia diagnosis according to the DSM-5.24 The current study adopted the Hong Kong-modified BIQ and a diagnosis of DSM-5 insomnia disorder was given if all the following criteria were met: (1) dissatisfaction with sleep quality or quantity; (2) complaint of one or more of the following sleep difficulties: difficulty initiating sleep, difficulty maintaining sleep, early morning awakening, or a nonrestorative sleep; (3) significant distress or interference with personal functioning in daily living caused by the sleep difficulty; (4) the sleep difficulty occurs at least three times a week; (5) the sleep difficulty is present for at least 3 months; and (6) the sleep difficulty occurs despite adequate opportunity and circumstances for sleep.

Functional Outcomes of Sleep Questionnaire

The Functional Outcomes of Sleep Questionnaire consists of 30 items that can be used to profile functional status due to sleep loss or excessive daytime sleepiness by probing the extent to which sleepiness or sleep disruption impairs five aspects of daily activities: general productivity, social outcomes, activity levels, vigilance, and sexual relationships.25 Respondents are asked to rate the difficulty of these activities on a four-point (extreme difficulty to no difficulty) Likert scale. Potential scores range from 5 to 20, with higher score indicating better functional status.

World Health Organization Well Being Index

The World Health Organization Well Being Index is a five-item scale that assesses the degree of subjective psychological well-being during the past 2 weeks based on positive mood (good spirits, relaxation), vitality (being active and waking up fresh and rested), and general interest (being interested in things).26 The total raw scores range from 0 (worst possible quality of life) to 25 (best possible quality of life).

Epworth Sleepiness Scale

The Epworth Sleepiness Scale consists of eight items on a four-point Likert scale from 0 (would never) to 3 (high chance) and is a self-report measure designed to assess the overall level of daytime sleepiness while engaged in eight different activities.27 Total scores range from 0 to 24, where higher score indicates greater propensity to fall asleep or “daytime sleepiness.”

Flinders Fatigue Scale

The Flinders Fatigue Scale is a brief seven-item assessment for measuring daytime fatigue over the previous two weeks.28 Six of the seven items are presented in Likert format and responses range from 0 (not at all) to 4 (extremely). Using a multiple item checklist to indicate more than one response, the fifth item measures the time of day when fatigue is experienced and the sum of this response is reported. Total scores range from 0 to 31 and higher score indicates greater fatigue.

Treatment History

A semistructured questionnaire was used to collect information on patients' past help-seeking experience for any lifetime insomnia-related sleep problems with a health care professional. This could be either a mental health care professional such as the patients' consulting psychiatrist and psychologist for their psychiatric treatment, or other non-mental health care professional including a sleep specialist, polyclinic doctor, general practitioner, or family doctor. Participants were first asked if they have ever consulted a professional for sleep problems and if yes, whether they have received a diagnosis of any specific sleep disorder(s) by the consulting professional. The type of interventions (medications, counseling/therapies, or others) received for their sleep problems were recorded and the effectiveness of the pharmacological intervention(s) received was also rated.

Statistical Analyses

Statistical analyses were performed using IBM SPSS, version 23 (IBM Corp, Armonk, New York, United States). Descriptive statistics were tabulated for the overall sample, along with their insomnia disorder status. Frequencies and percentages were calculated for categorical variables, whereas mean and standard deviation were calculated for all other continuous variables. Chi-square tests and independent t tests were performed to analyze differences for categorical and continuous variables, respectively. Statistical significance was set at P < .05.


Patient Characteristics

The profile of the sample is shown in Table 1. The sample was composed of mostly males (52.5%), in the younger age group of 21 to 39 years (55.0%), Chinese (37.8%), never married (58.3%), completed postsecondary/pretertiary education (41.0%), and employed (54.8%). The majority of them had illness duration of more than 5 years (65.8%) and diagnosis made between the age of 21 to 39 years (56.8%). In terms of comorbidities, 47.0% had a secondary psychiatric diagnosis and 59.5% had a chronic medical condition.

Characteristics of participants based on total sample and by DSM-5 insomnia disorder status.


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Table 1

Characteristics of participants based on total sample and by DSM-5 insomnia disorder status.

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Insomnia Prevalence

The prevalence of DSM-5 insomnia disorder in the current sample was 31.8% (n = 127) based on the modified BIQ.

Bivariate analyses (Table 1) revealed those with DSM-5 insomnia disorder differed from those without the disorder in terms of age group, employment, level of physical activity, their use of sleeping pills and the presence of a secondary psychiatric diagnosis. It was more prevalent among the younger age group (21 to 39 years), the unemployed, those who had low physical activity level, those who had a secondary psychiatric diagnosis, and those who were on sleep medications.

The prevalence of DSM-5 insomnia was highest among those with depressive disorder (45.0%), followed by anxiety disorder (33.0%), schizophrenia spectrum disorder (25.0%), and bipolar disorder (23.8%). Chi-square analysis (Table 2) revealed a significant difference in the rates of DSM-5 insomnia among the different psychiatric disorders (P = .005). In terms of the nature of sleep difficulties, chi-square analyses revealed only significant differences (P < .001) for both difficulty initiating and maintaining sleep across the four psychiatric disorders. No significant difference was reported for early morning awakening and nonrestorative sleep.

Insomnia and its related symptoms across four primary diagnoses.


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Table 2

Insomnia and its related symptoms across four primary diagnoses.

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Impairment Outcomes and Mental Health Services Utilization in the Past Year

Table 3 shows that those with insomnia disorder had significantly higher impairment outcomes in areas of functioning, well-being, and daytime fatigue compared to those without. However, no group difference was observed for daytime sleepiness, as well as any mental health services utilization including outpatients, emergency services, psychotherapy, and hospitalization visits in the past year. Despite being nonsignificant, those with insomnia disorder had higher mental health services utilization than those without.

Differences in impairment outcomes and mental health services utilization between those with and without DSM-5 insomnia disorder.


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Table 3

Differences in impairment outcomes and mental health services utilization between those with and without DSM-5 insomnia disorder.

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Self-Reported Help-Seeking Experience for Sleep Disturbance

Of the 400 psychiatric patients interviewed, 50.0% (n = 200) reported having sought help from a health care professional for any insomnia-related sleep difficulties. Of these 200 patients, 7.0% (n = 14) were not recommended any treatment specific to their sleep problems. Only 12.5% of patients (n = 25) recalled being informed of their insomnia diagnosis by their doctors and only 12.0% of patients (n = 24) recounted being educated on sleep hygiene or receiving any form of psychotherapy for their sleep problems. A total of 91.0% of patients (n = 182) were prescribed psychotropic medications or sleeping pills to aid them in their sleep, of which 74.2% (n = 135) found the drug treatment to be helpful but to varying extent. Common concerns were, however, daytime drowsiness (n = 23), nonsustained effectiveness (n = 21), and drug dependence (n = 18).


The current study focused on insomnia in the context of a group of psychiatric patients at risk of sleep disturbance by examining the prevalence and factors of DSM-5 insomnia disorder among them, as well as their treatment history for insomnia-related problems. Together with the International Classification of Sleep Disorders, Third Edition, the contrast between primary and secondary insomnia has been removed due to the difficulty in establishing the cause/effect relationship between insomnia and other psychiatric or medical conditions with certainty.29 This major revision was a move consistent with the recommendations of the 2005 National Institutes of Health State of the Science position on the classification of insomnia disorders.30 The DSM-5 Sleep-Wake Disorders Work Group took into consideration the pathological and etiological factors associated with sleep-wake disorders, and thus incorporated these changes with the aim to increase uniformity and consistency among health care professionals when they are assessing and treating patients with various sleep disorders.31 Consequently, the examination of DSM-5 insomnia disorder among individuals with psychiatric disorders becomes more meaningful without having to differentiate primary and secondary insomnia and allows for useful comparison with other populations. Furthermore, DSM-5 has been recognized as a widely adopted psychiatric taxonomy for mental disorders in its latest edition, and is therefore familiar to psychiatrists and mental health care professionals.

DSM-5 Insomnia Disorder

In view of the aforementioned details, our study adopted the modified BIQ to estimate insomnia prevalence in accordance with the DSM-5 criteria. Our study revealed almost one-third of our psychiatric sample (31.8%) to be suffering from a clinically significant sleep disorder (ie, insomnia disorder). To the best of our knowledge, only one study has reported on insomnia prevalence using diagnostic criteria of the International Classification of Diseases, one of the three main classifications for sleep disorders in a psychiatric population. The prevalence of International Classification of Diseases, Tenth Revision insomnia was found to be 20.1% in a group of psychiatric outpatients with diversified diagnoses.32 Despite the requirement of a longer duration of 3 months for the experienced sleep difficulty in DSM-5 compared to 1 month in International Classification of Diseases, Tenth Revision, the higher prevalence in our study may be attributed to the use of a psychiatric sample with only four diagnoses that are at higher risk of insomnia. Studies reporting prevalence of DSM-5 insomnia in other populations have been limited. The Nord-Trøndelag Health Study has established an adjusted DSM-5 insomnia prevalence of 7.9% among a general adult population in Norway,33 whereas the weighted prevalence in Hong Kong population was found to be 10.8%,34 both of which were lower than our reported prevalence of 31.8% in a psychiatric outpatient sample. The need to screen for clinical insomnia among psychiatric patients using an appropriate and easy-to-administer tool has therefore become important.35

The lack of studies using a standardized diagnostic instrument to estimate prevalence of clinical insomnia among psychiatric populations in a single study makes the comparison of insomnia prevalence across differential psychiatric disorders less reliable and consistent. Our findings revealed decreasing DSM-5 insomnia disorder prevalence across major depressive disorder (45.0%), followed by anxiety disorders (33.0%), schizophrenia spectrum disorder (25.0%), and bipolar affective disorder (23.8%). Ogbolu et al.,32 however, found International Classification of Diseases, Tenth Revision nonorganic insomnia to be more prevalent among those with major depression (n = 15, 33.3%), followed by bipolar affective disorder (n = 6, 24.0%), anxiety and other neurotic disorders (n = 3, 18.8%), and schizophrenia (n = 7, 10.6%) using diagnostic groups of smaller sample size. Nonetheless, the literature does seem to suggest the close relationship of insomnia with depression and anxiety disorders.36,37 Studies in community-based and non-psychiatric clinical samples have also found a high proportion of 40% to 60% of individuals with insomnia to suffer from mainly depression or anxiety disorder, among other mental disorders.4,3842

Insomnia Treatment in Psychiatric Patients

In the current study, those with current DSM-5 insomnia disorder were found to have significantly higher impairment outcomes in terms of functioning, well-being, and daytime fatigue than those without. Yet, the mental health services utilization in the past year among them was higher but not significantly higher, compared to their counterparts. This may imply that the psychiatric patients in our sample were not receiving adequate treatment that corresponds to the level of impairment due to their clinical insomnia. Nonetheless, further research would need to be done to explain this lack of service utilization among those with insomnia disorder despite suffering from significantly worse daytime consequences and quality of life. One study exploring the lack of help-seeking for insomnia among primary care patients has proposed that the problem may not be due to the clinician's failure to identify and treat sleep problems but because patients with syndrome-defined insomnia do not view it as a clinically significant disorder that warrants medical attention.43 Although studies generally supported that perceived greater daytime impairment would better prompt patients to seek treatment,43,44 it has been suggested that patients' sleep and treatment beliefs, as well as the ease of accessing specialized care (including level of awareness, referral mechanisms, availability of service providers and cost of treatment), may also play a role in their help-seeking behaviors for sleep problems.44 Supported in an earlier study, 28.4% denied having any sleep problem and 39.8% did not seek help among those who reported poor sleep quality based on the Pittsburgh Sleep Quality Index in our sample.45 The current study also revealed that only 12.5% among those who sought treatment for their sleep difficulties (n = 25) recalled being told by their doctors that they had insomnia. This low rate of diagnosis for insomnia may be due to clinicians' attribution of the patients' sleep problems to be secondary to their psychiatric or other medical disorders and possible recall bias. Because the clinical manifestations are similar, sleep disorders may often be mistakenly attributed to the patient's primary psychiatric condition.46 In addition, our data showed that those who were currently on sleep medications had a higher rate of DSM-5 insomnia disorder compared to those without, hence suggesting that medications alone may not be the best treatment for their insomnia symptoms. Although most of those who sought help and were given psychotropic medications to aid in their sleep did find the pharmacological treatment improved their sleep, the prevalence of DSM-5 insomnia disorder based on the BIQ among them remains high at 31.8%. The use of psychological and behavioral therapies such as cognitive behavioral therapy or combined treatment with drug intervention to treat chronic insomnia has been strongly advocated in medical practice.1,47 However, only 12.0% (n = 24) of patients who sought help reported having received psychoeducation or psychotherapy for their sleep problems from a health care professional. This findings, when taken together, seem to suggest there is a lack of emphasis given to the treatment of insomnia among psychiatric patients.

Strengths and Limitations

The study of insomnia in psychiatric patients may not be novel. However, existing studies have mainly looked at insomnia symptoms or disturbance and only one study seems to have applied the diagnostic criteria for insomnia from existing classification systems.32 Most epidemiological studies that examined the associations between psychiatric disorders and insomnia were studied in population-based samples,4,3639,48 which generally reported lower prevalence that is not surprising. Studying the relationship of sleep and mental disorders from the perspective of treatment-seeking psychiatric patients is equally important. Our study may also be unique in that we shed some light on the management and treatment of insomnia in this population in view of the recommendations by the DSM-5 Sleep-Wake Disorders Work Group by looking at their treatment contact for sleep disturbance and evaluating the extent to which their sleep problems have been addressed.

Our study is not without its limitations. The current study was conducted in a single clinical setting within Singapore and has adopted a convenient sampling strategy that recruited only patients with specific mental diagnoses, thus limiting the generalizability of our findings to a larger population of psychiatric patients. The endorsement of DSM-5 insomnia disorder requires the sleep disturbance not to occur exclusively during the course of narcolepsy, sleep-related breathing disorder, circadian rhythm sleep disorder, or parasomnia but this criterion was not operationalized within the BIQ. We did not assess these sleep disorders other than insomnia, which may have influenced some of the variables studied, such as daytime sleepiness and functioning. Last, the cross-sectional design of the study does not allow us to establish a causal relationship between insomnia disorder and psychiatric disorders.


The current study suggests that almost one-third of our psychiatric outpatients may be suffering from comorbid DSM-5 insomnia disorder, a sleep disorder that warrants further medical attention. Consistent with the literature, our study provides further support through a single empirical study on the higher rate of insomnia among those with affective disorders compared to schizophrenia spectrum disorders. Evidence from our study also is indicative of the undermining of sleep symptoms as a clinically significant problem in this population, both from the patients' and/or the clinicians' perspective. As a result, there is a lower priority given to treat these sleep symptoms compared to their psychiatric disorder. With the new calling from DSM-5, clinicians treating psychiatric patients should view insomnia less as a symptom of their mental illnesses and place more focus on treating insomnia as a disorder itself, which has been shown to help alleviate concurrent psychiatric symptoms. In addition, the presence of a mental illness should not be a distraction from a holistic evaluation of insomnia as a presenting problem. Nonmedical (cognitive and behavioral) interventions for insomnia need to be further explored among psychiatric patients given their proven clinical effectiveness. Greater awareness on the consequences of poor sleep and the importance of treating insomnia should also be raised among the patient group. As other sleep disorders such as obstructive sleep apnea may also be responsible for poor sleep, referral to a sleep specialist for further evaluation should be considered.


Work for this study was performed at the Institute of Mental Health, Singapore. This research is supported by the Singapore Ministry of Health's National Medical Research Council under the Centre Grant Programme (Grant No.: NMRC/ CG/004/2013). The authors report no conflicts of interest. All authors have seen and approved the manuscript.



major depressive disorder


Diagnostic and Statistical Manual of Mental Disorders


International Classification of Diseases


International Classification of Sleep Disorders


Brief Insomnia Questionnaire


Functional Outcomes of Sleep Questionnaire


World Health Organization


Epworth Sleepiness Scale


Flinders Fatigue Scale



Schutte-Rodin S, Broch L, Buysse D, Dorsey C, Sateia M. Clinical Guideline for the Evaluation and Management of Chronic Insomnia in Adults. J Clin Sleep Med. 2008;4(5):487–504. [PubMed Central][PubMed]


Smith MT, Perlis ML, Park A, et al. Comparative meta-analysis of pharmacotherapy and behavior therapy for persistent insomnia. Am J Psychiatry. 2002;159(1):5–11. [PubMed]


Krystal AD. Psychiatric disorders and sleep. Neurol Clin. 2012;30(4):1389–1413. [PubMed Central][PubMed]


Ford DE, Kamerow DB. Epidemiologic study of sleep disturbances and psychiatric disorders. An opportunity for prevention? JAMA. 1989;262(11):1479–1484. [PubMed]


Abad VC, Guilleminault C. Sleep and psychiatry. Dialogues Clin Neurosci. 2005;7(4):291–303. [PubMed Central][PubMed]


Baglioni C, Nanovska S, Regen W, et al. Sleep and mental disorders: A meta-analysis of polysomnographic research. Psychol Bull. 2016;142(9):969–990. [PubMed Central][PubMed]


Reddy MS, Chakrabarty A. “Comorbid” Insomnia. Indian J Psychol Med. 2011;33(1):1–4. [PubMed Central][PubMed]


Anderson KN, Bradley AJ. Sleep disturbance in mental health problems and neurodegenerative disease. Nat Sci Sleep. 2013;5:61–75. [PubMed Central][PubMed]


Seow LSE, Subramaniam M, Abdin E, Vaingankar JA, Chong SA. Sleep disturbance among people with major depressive disorders (MDD) in Singapore. J Mental Health. 2016;25(6):1–8.


Thase ME. Antidepressant treatment of the depressed patient with insomnia. J Clin Psychiatry. 1999;60 Suppl 17:28–31; discussion 46-28. [PubMed]


Nutt D, Wilson S, Paterson L. Sleep disorders as core symptoms of depression. Dialogues Clin Neurosci. 2008;10(3):329–336. [PubMed Central][PubMed]


Harvey AG, Talbot LS, Gershon A. Sleep disturbance in bipolar disorder across the lifespan. Clin Psychol (New York). 2009;16(2):256–277.


Green B. Post-traumatic stress disorder: symptom profiles in men and women. Curr Med Res Opin. 2003;19(3):200–204. [PubMed]


Monti JM, Monti D. Sleep disturbance in generalized anxiety disorder and its treatment. Sleep Med Rev. 2000;4(3):263–276. [PubMed]


Freeman D, Pugh K, Vorontsova N, Southgate L. Insomnia and paranoia. Schizophr Res. 2009;108(1-3):280–284. [PubMed Central][PubMed]


Palmese LB, DeGeorge PC, Ratliff JC, et al. Insomnia is frequent in schizophrenia and associated with night eating and obesity. Schizophr Res. 2011;133(1-3):238–243. [PubMed Central][PubMed]


Chong SA, Abdin E, Vaingankar JA, et al. A population-based survey of mental disorders in Singapore. Ann Acad Med Singapore. 2012;41(2):49–66. [PubMed]


Subramaniam M, Abdin E, Vaingankar JA, Verma S, Chong SA. Latent structure of psychosis in the general population: results from the Singapore mental health study. Psychol Med. 2014;44(1):51–60. [PubMed]


Kuppermann M, Lubeck DP, Mazonson PD, et al. Sleep problems and their correlates in a working population. J Gen Intern Med. 1995;10(1):25–32. [PubMed]


Walsh JK. Clinical and socioeconomic correlates of insomnia. J Clin Psychiatry. 2004;65 Suppl 8:13–19.


Kallestad H, Hansen B, Langsrud K, et al. Impact of sleep disturbance on patients in treatment for mental disorders. BMC Psychiatry. 2012;12(1):179.


Reynolds CF, O'Hara R. DSM-5 Sleep-wake disorders classification: overview for use in clinical practice. Am J Psychiatry. 2013;170(10):1099–1101. [PubMed]


Kessler RC, Coulouvrat C, Hajak G, et al. Reliability and validity of the brief insomnia questionnaire in the America insomnia survey. Sleep. 2010;33(11):1539–1549. [PubMed Central][PubMed]


Chung KF, Yeung WF, Ho FY, et al. Validity and reliability of the Brief Insomnia Questionnaire in the general population in Hong Kong. J Psychosom Res. 2014;76(5):374–379. [PubMed]


Weaver TE, Laizner AM, Evans LK, et al. An instrument to measure functional status outcomes for disorders of excessive sleepiness. Sleep. 1997;20(10):835–843. [PubMed]


Bech P. Measuring The Dimensions of Psychological Well-Being by the WHO-5. QoL Newsletter. 2004;32:15–16.


Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep. 1991;14(6):540–545. [PubMed]


Gradisar M, Lack L, Richards H, et al. The Flinders Fatigue Scale: Preliminary Psychometric Properties and Clinical Sensitivity of a New Scale for Measuring Daytime Fatigue associated with Insomnia. J Clin Sleep Med. 2007;3(7):722–728. [PubMed Central][PubMed]


Sateia MJ. International classification of sleep disorders-third edition: highlights and modifications. Chest. 2014;146(5):1387–1394. [PubMed]


NIH State-of-the-Science Conference Statement on manifestations and management of chronic insomnia in adults. NIH Consens State Sci Statements. 2005;22(2):1–30. [PubMed]


Reynolds CF, Redline S. The DSM-V sleep-wake disorders nosology: an update and an invitation to the sleep community. Sleep. 2010;33(1):10–11. [PubMed Central][PubMed]


Ogbolu RE, Aina OF, Famuyiwa OO, Erinfolami AR. A study of insomnia among psychiatric out-patients in Lagos Nigeria. J Sleep Disord Ther. 2012;1(4):104.


Uhlig BL, Sand T, Odegard SS, Hagen K. Prevalence and associated factors of DSM-V insomnia in Norway: the Nord-Trondelag Health Study (HUNT 3). Sleep Med. 2014;15(6):708–713. [PubMed]


Chung KF, Yeung WF, Ho FY, Yung KP, Yu YM, Kwok CW. Cross-cultural and comparative epidemiology of insomnia: the Diagnostic and statistical manual (DSM), International classification of diseases (ICD) and International classification of sleep disorders (ICSD). Sleep Med. 2015;16(4):477–482. [PubMed]


Esmond Seow LS, Abdin E, Sherilyn Chang S, Chong SA, Subramaniam M. Identifying the best sleep measure to screen clinical insomnia in a psychiatric population. Sleep Med. 2018;41:86–93


Taylor DJ, Lichstein KL, Durrence HH, Reidel BW, Bush AJ. Epidemiology of insomnia, depression, and anxiety. Sleep. 2005;28(11):1457–1464. [PubMed]


Ohayon MM, Roth T. Place of chronic insomnia in the course of depressive and anxiety disorders. J Psychiatr Res. 2003;37(1):9–15. [PubMed]


Breslau N, Roth T, Rosenthal L, Andreski P. Sleep disturbance and psychiatric disorders: a longitudinal epidemiological study of young adults. Biol Psychiatry. 1996;39(6):411–418. [PubMed]


Ohayon MM. Prevalence of DSM-IV diagnostic criteria of insomnia: distinguishing insomnia related to mental disorders from sleep disorders. J Psychiatr Res. 1997;31(3):333–346. [PubMed]


Schramm E, Hohagen F, Kappler C, Grasshoff U, Berger M. Mental comorbidity of chronic insomnia in general practice attenders using DSM-III-R. Acta Psychiatr Scand. 1995;91(1):10–17. [PubMed]


Tan TL, Kales JD, Kales A, Soldatos CR, Bixler EO. Biopsychobehavioral correlates of insomnia. IV: diagnosis based on DSM-III. Am J Psychiatry. 1984;141(3):357–362. [PubMed]


Buysse DJ, Reynolds CF 3rd, Kupfer DJ, et al. Clinical diagnoses in 216 insomnia patients using the International Classification of Sleep Disorders (ICSD), DSM-IV and ICD-10 categories: a report from the APA/NIMH DSM-IV Field Trial. Sleep. 1994;17(7):630–637. [PubMed]


Aikens JE, Rouse ME. Help-seeking for insomnia among adult patients in primary care. J Am Board Fam Pract. 2005;18(4):257–261. [PubMed]


Cheung JM, Bartlett DJ, Armour CL, Glozier N, Saini B. Insomnia patients' help-seeking experiences. Behav Sleep Med. 2014;12(2):106–122. [PubMed]


Chang S, Seow E, Koh SHD, et al. Treatment preferences and help-seeking behaviors for sleep problems among psychiatric outpatients. Gen Hosp Psychiatry. 2017 Aug. 12. [Epub ahead of print]. [PubMed Central]


Stores G. Misdiagnosing sleep disorders as primary psychiatric conditions. Adv Psychiatr Treat. 2003;9(1):69–77.


Siebern AT, Suh S, Nowakowski S. Non-pharmacological treatment of insomnia. Neurotherapeutics. 2012;9(4):717–727. [PubMed Central][PubMed]


Sarsour K, Morin CM, Foley K, Kalsekar A, Walsh JK. Association of insomnia severity and comorbid medical and psychiatric disorders in a health plan-based sample: Insomnia severity and comorbidities. Sleep Med. 2010;11(1):69–74. [PubMed]