The Open Public Health Journal




ISSN: 1874-9445 ― Volume 14, 2021
RESEARCH ARTICLE

Impact of Sleep Disturbances on the Quality of Life Among Schizophrenic Out-patients of Jimma University Medical Center, Southwest Ethiopia: Hospital Based Cross-sectional Study



Aman Dule1, *, Mustefa Mohammedhussein1, Mohammedamin Hajure1
1 Department of Psychiatry, Faculty of Public Health and Medical Science, Mettu University, Mettu, Ethiopia

Abstract

Aim:

Current study was aimed to assess the impacts of sleep disturbances on patient’s quality of life.

Background:

Schizophrenia is a syndrome, which affects sleep. Up to 80% of schizophrenic patients complain of sleep disturbances which affect the quality of life

Objectives:

To assess the association of sleep disturbances and quality of life and other contributing factors among schizophrenic patients on follow-up treatment at Jimma University Southwest Ethiopia.

Methods:

A cross-sectional study with a consecutive sampling of 411 out-patients at Jimma University medical center was employed from April 21-June 20, 2019. Sleep disturbances and the quality of life were assessed by Pittsburgh sleep quality index and WHOQOL-BREF, respectively. Epi data version 3.1 and SPSS version 23.0 software was used. Chi-square and independent samples t-test were used for association and P-value < 0.05 was considered for statistical significance.

Results:

Most participants had sleep disturbances and the mean score of positive scale on PANSS was higher for patients with sleep disturbances. About one-fourth of the patients had very good subjective sleep quality and > 85% of sleep efficiency was reported by 139 participants. More than half (51.1%) of the subjects had used sleep medication and the majority (64.7%) of them were reported daytime dysfunctions in the past month. The social domain (M±SD=3.92±2.51, t=8.46, p= <0.001, eta2=0.15) and overall WHOQOL (M±SD=57.60±16.87, t=9.24, p= < 0.001, eta2= 0.17) score had a large difference of means and about 15% and 17% of the variance in sleep disturbance have been explained.

Conclusion:

Generally, the finding of the current study was in agreement with most of the previous studies and sleep disturbances respectively moderate to significant effects on the patient’s quality of life.

Keywords: Sleep disturbance, Out-patients, Quality of life, PANSS, Jimma, Ethiopia.


Article Information


Identifiers and Pagination:

Year: 2020
Volume: 13
First Page: 684
Last Page: 691
Publisher Id: TOPHJ-13-684
DOI: 10.2174/1874944502013010684

Article History:

Received Date: 17/5/2020
Revision Received Date: 7/10/2020
Acceptance Date: 8/10/2020
Electronic publication date: 18/12/2020
Collection year: 2020

© 2020 Dule et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


* Address correspondence to this author at Department of Psychiatry, Faculty of Public Health and Medical Science, Mettu University, Mettu, Ethiopia; Tel: +251911418771/+251932848553; E-mail: amandule1993@gmail.com





1. INTRODUCTION

1.1. Sleep Disturbances in Patients with Schizophrenia

Schizophrenia is a syndrome and serious psychotic illness which comprises a number of problems. It interferes with the patient’s life and affects a wide range of domains like emotion, behavior, perceptions, thoughts, and sleep. Sleep is a physiological process in which awareness of external stimuli is decreased and is crucial to the optimal functioning of the body and mind [1Benjamin J. Sadock MD, Virginia A. Sadock MD, Pedro R. MD. Synopsis of psychiatry behavioral sciences/clinical psychiatry 11th edt. 2015; 649-52., 2Pritchett D, Wulff K, Oliver PL, et al. Evaluating the links between schizophrenia and sleep and circadian rhythm disruption. J Neural Transm (Vienna) 2012; 119(10): 1061-75.
[http://dx.doi.org/10.1007/s00702-012-0817-8] [PMID: 22569850]
].

Sleep disturbances are distressing symptoms that are common among various ranges of psychiatric disorders and affect up to 80% of schizophrenic patients [3Ered A, Cooper S, Ellman LM. Sleep quality, psychological symptoms, and psychotic-like experiences. J Psychiatr Res 2018; 98(98): 95-8.
[http://dx.doi.org/10.1016/j.jpsychires.2017.12.016] [PMID: 29331930]
]. It gives ways to the maintenance of psychotic symptoms and functional disabilities [4Laskemoen JF, Simonsen C, Büchmann C, et al. Sleep disturbances in schizophrenia spectrum and bipolar disorders - a transdiagnostic perspective. Compr Psychiatry 2019; 91: 6-12.
[http://dx.doi.org/10.1016/j.comppsych.2019.02.006] [PMID: 30856497]
-6Ered A, Cooper S, Ellman LM. Sleep quality, psychological symptoms, and psychotic-like experiences. J Psychiatr Res 2018; 98: 95-8.
[http://dx.doi.org/10.1016/j.jpsychires.2017.12.016] [PMID: 29331930]
]. Difficulty in initiating sleep, early awakening and inability to fall asleep back, and reduced slow wave-sleep were repeatedly documented by polysomnography at any phase of the illness although its relation to the Quality Of Life (QOL) is not well known in the current setting [7Hofstetter JR, Lysaker PH, Mayeda AR. Quality of sleep in patients with schizophrenia is associated with quality of life and coping. BMC Psychiatry 2005; 5(13): 13.
[http://dx.doi.org/10.1186/1471-244X-5-13] [PMID: 15743538]
]. Data were limited in Ethiopia concerning the sleep disturbances in patients with schizophrenia and previously, it was reported that the use of antipsychotics was significantly related to disturbed sleep like sedation [8Wubeshet YS, Mohammed OS, Desse TA. Prevalence and management practice of first generation antipsychotics induced side effects among schizophrenic patients at Amanuel Mental Specialized Hospital, central Ethiopia: cross-sectional study. BMC Psychiatry 2019; 19(1): 32.
[http://dx.doi.org/10.1186/s12888-018-1999-x] [PMID: 30658604]
] and the presence of these side effects along with other factors had related to poor medication adherence [9Eticha T, Teklu A, Ali D, Solomon G, Alemayehu A. Factors associated with medication adherence among patients with schizophrenia in Mekelle, Northern Ethiopia. PLoS One 2015; 10(3)e0120560
[http://dx.doi.org/10.1371/journal.pone.0120560] [PMID: 25816353]
].

1.2. Sleep Pattern and Quality of Life Among Schizophrenic Patients

QOL is a multidimensional complex issue, a holistic approach and broader concept which contains social, functional, physical, economical, and emotional well-being of a person. It comprises different medical and psychosocial aspects such as daily living activities, awareness of own health status, psychological well-being and satisfaction with life and difficult to explain. Unlike previous decades, it is getting attention currently because of growing concerns about the disappointing life of patients with chronic mental illnesses like schizophrenia [10Theofilou P. Quality of life: Definition and measurement. Eur J Psychol 2013; 9(1): 150-62.
[http://dx.doi.org/10.5964/ejop.v9i1.337]
-12Chaturvedi SK, Muliyala KP. The Meaning in Quality of Life. J Psychosoc Rehabil Ment Health 2016; 3(2): 47-9.
[http://dx.doi.org/10.1007/s40737-016-0069-2]
].

Health Related-Quality of Life (HRQOL) is a subjective awareness of the patient’s own health and illness and its management. This can be widely affected by sleep disturbance, although their relation is poorly studied in developing countries [13Azaiez C, Millier A, Lançon C, et al. Health related quality of life in patients having schizophrenia negative symptoms - a systematic review. J Mark Access Health Policy 2018; 6(1)1517573
[http://dx.doi.org/10.1080/20016689.2018.1517573] [PMID: 30275939]
, 14Darchia N, Oniani N, Sakhelashvili I, et al. Relationship between sleep disorders and health related quality of life: Results from the Georgia Somnus study. Int J Environ Res Public Health 2018; 15(8): 1-15.
[http://dx.doi.org/10.3390/ijerph15081588] [PMID: 30049991]
].

Sleeping under the recommended time (five hours or less) is linked with different negative consequences of one’s health like poor mental health, increased severity of symptoms, causing chronic medical illness, low quality of life, and elevated suicide rate [15Peltzer K, Pengpid S. Self-reported sleep duration and its correlates with sociodemographics, health behaviours, poor mental health, and chronic conditions in rural persons 40 years and older in South Africa. Int J Environ Res Public Health 2018; 15(7): 1-9.
[http://dx.doi.org/10.3390/ijerph15071357] [PMID: 29958407]
, 16Kim TK, Lee HC, Lee SG, Han KT, Park EC, Park E. The combined effect of sleep duration and quality on mental health among Republic of Korea armed forces. Mil Med 2016; 181(11): e1581-9.
[http://dx.doi.org/10.7205/MILMED-D-15-00538] [PMID: 27849493]
]. As a report indicated, patients with schizophrenia with all types of sleep disturbances more likely had poor quality of life and they had a suicidal attempt and committed suicide about 13 times more than those without sleep disturbances [17Sutton EL. Psychiatric disorders and sleep issues. Med Clin North Am 2014; 98(5): 1123-43.
[http://dx.doi.org/10.1016/j.mcna.2014.06.009] [PMID: 25134876]
].

Decreased Non-rapid Eye Movement (NREM) and Rapid Eye Movement (REM), fragmented sleep, altered sleep timing; reduced sleep continuity and sleep disturbance are highly prevalent in schizophrenia and negatively affect the quality of life [18Winsky-Sommerer R, de Oliveira P, Loomis S, Wafford K, Dijk DJ, Gilmour G. Disturbances of sleep quality, timing and structure and their relationship with other neuropsychiatric symptoms in Alzheimer’s disease and schizophrenia: Insights from studies in patient populations and animal models. Neurosci Biobehav Rev 2019; 97: 112-37.
[http://dx.doi.org/10.1016/j.neubiorev.2018.09.027] [PMID: 30312626]
]. Sleep disturbances affect large number of schizophrenic patients and cause psychological distress, social impairment, cognitive functioning problems, and disturbing health-related quality of life [19Van Den Noort M, Staudte H, Perriard B, Yeo S, Lim S, Bosch P. Schizophrenia and comorbid sleep disorders. Neuroimmunol Neuroinflamm 2016; 3: 225-7.
[http://dx.doi.org/10.20517/2347-8659.2016.42]
].

Disturbed sleep and sleep disorders linked to dangerous accidents, decreased productivity at work, and disturbed psychological functioning. Literature showed that the work-related accident is doubled in people with sleeping difficulty and prolonged sleep disturbance has negatively affected individual well-being and quality of life. It is also reported that about 40% of people with sleep disturbances, especially insomnia were diagnosed with at least one psychiatric illness [20Sahin NH. Specific Quality of Life Measures for Sleep Disorders https//www.researchgate.net/publication/2219286272014.]. It is also reported that sleep disturbance worsens all domains of quality of life independent of comorbid illness and good sleep quality instantly helps in the sustainment of physical functioning and mental wellbeing [21Lee M, Choh AC, Demerath EW, et al. Sleep disturbance in relation to health-related quality of life in adults: the Fels Longitudinal Study. J Nutr Health Aging 2009; 13(6): 576-83.
[http://dx.doi.org/10.1007/s12603-009-0110-1] [PMID: 19536428]
].

Despite the association of sleep disturbances with wide ranges of symptoms like excessive tension, drowsiness, bad mood and self-harm, little is known regarding the concerning patterns of sleep disturbances in a variety of psychiatric illnesses in the sub-Saharan countries [22Kia Byrd, Bizu Gelaye, Mahlet G. Tadessea, Michelle A. Williams, Seblewengel Lemma and YB. Sleep Disturbances and Common Mental Disorders in College Students. Health Behav Policy Rev 2014; 1(3): 229-37.
[http://dx.doi.org/10.14485/HBPR.1.3.7] [PMID: 25309939]
].

Although it is often dominated by other clinical concerns like positive symptoms of psychosis, sleep problems are common among schizophrenic patients and linked to weight gain risk, impaired cognition, and lower quality of life and affect more than 90% of psychiatry hospitalized patients [23de Niet GJ, Tiemens BG, Lendemeijer HH, Hutschemaekers GJ, Hutschemaekers G. Perceived sleep quality of psychiatric patients. J Psychiatr Ment Health Nurs 2008; 15(6): 465-70.
[http://dx.doi.org/10.1111/j.1365-2850.2008.01250.x] [PMID: 18638206]
]. A study that was conducted on 20 individuals with schizophrenia reported as patients with schizophrenia had longer sleep period, sleep latency and time spent in bed and fragmented sleep. This can cause chronically disturbed sleep, which highly affects their social interactions, productivity, and quality of life [24Wulff K, Dijk DJ, Middleton B, Foster RG, Joyce EM. Sleep and circadian rhythm disruption in schizophrenia. Br J Psychiatry 2012; 200(4): 308-16.
[http://dx.doi.org/10.1192/bjp.bp.111.096321] [PMID: 22194182]
].

Another study among 617 schizophrenic patients showed that 78% of sleep disturbances and revealed as insomnia and delayed sleep onset were frequent, and they had severe symptoms and poorer functioning than patients without sleep disturbances [4Laskemoen JF, Simonsen C, Büchmann C, et al. Sleep disturbances in schizophrenia spectrum and bipolar disorders - a transdiagnostic perspective. Compr Psychiatry 2019; 91: 6-12.
[http://dx.doi.org/10.1016/j.comppsych.2019.02.006] [PMID: 30856497]
]. One study of sleep diary and wrist-actigraphy recordings also showed that patients with schizophrenia had poor sleep efficiency, irregular sleep-wake cycle, delayed sleep onset and high score on PSQI than healthy subjects and healthy subjects had a higher score on all domains of QOL compared to schizophrenic patients [25Afonso P, Figueira ML, Paiva T. Sleep-wake patterns in schizophrenia patients compared to healthy controls. World J Biol Psychiatry 2014; 15(7): 517-24.
[http://dx.doi.org/10.3109/15622975.2012.756987] [PMID: 23316764]
].

Another study reported elongated sleep latency, decreased sleep efficiency and increased nighttime awakening [26Monti JM, BaHammam AS, Pandi-Perumal SR, et al. Sleep and circadian rhythm dysregulation in schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2013; 43: 209-16.
[http://dx.doi.org/10.1016/j.pnpbp.2012.12.021] [PMID: 23318689]
] and another study showed as almost half the patients had poor sleep quality and 24.7% of them were reported to have excessive daytime dysfunction, which has an impact on their daily living functioning and disturbed HRQOL [27Campos EDM, Melo CM, Maia WS, Felipe P, De Bruin C, Ponte L, et al. Sleep disturbances and gender differences in schizophrenia. Sleep Sci 2008; 1(9): 27-30.]. One systematic review also reported that sleep disturbances are high (75-80%) among schizophrenic patients with severe psychotic experiences and 50% of them had insomnia and 48% of them had reported nightmares [5Waite F, Sheaves B, Isham L, Reeve S, Freeman D. Sleep and schizophrenia: From epiphenomenon to treatable causal target. Schizophr Res 2019; xxxx(xxxx): 1-13.].

It is also reported that patients with schizophrenia had increased sleep latency, repeated sleep interruption and about 50-70% of them had sleep disturbances [28Waters F, Manoach DS. Sleep dysfunctions in schizophrenia : A practical review. Open J Psychiatr 2012; 2: 384-92.
[http://dx.doi.org/10.4236/ojpsych.2012.224054]
], and they had problems with sleeping, and had irregular sleep patterns, which cause them daytime dysfunctions and emotional instability [29Waite F, Evans N, Myers E, et al. The patient experience of sleep problems and their treatment in the context of current delusions and hallucinations. Psychol Psychother 2016; 89(2): 181-93.
[http://dx.doi.org/10.1111/papt.12073] [PMID: 26285922]
]. As the literature showed, schizophrenic patients who had low educational status and lower economic status and those living in a large family had been associated with more sleep disturbances [30Ma XR, Song GR, Xu XB, Tian T, Chang SH, Cdo DS. The Prevalence of Sleep Disturbance and Its Socio-demographic and Clinical Correlates in First-episode Individuals With Schizophrenia in Rural China. Perspect Psychiatr Care 2018; 54(1): 31-8.
[http://dx.doi.org/10.1111/ppc.12197] [PMID: 27861956]
] and other results revealed that older age was linked to low risk of sleep disturbances and women sex associated with longer sleep time, shorter sleep latency and higher sleep efficiency [31Subramaniam M, Abdin E, Shahwan S, et al. Prevalence, correlates and outcomes of insomnia in patients with first episode psychosis from a tertiary psychiatric institution in Singapore. Gen Hosp Psychiatry 2018; 51: 15-21.
[http://dx.doi.org/10.1016/j.genhosppsych.2017.11.009] [PMID: 29268166]
, 32Lemola S, Ledermann T, Friedman EM. Variability of sleep duration is related to subjective sleep quality and subjective well-being: an actigraphy study. PLoS One 2013; 8(8)e71292
[http://dx.doi.org/10.1371/journal.pone.0071292] [PMID: 23967186]
]. It is also reported that sleep disturbances were associated with older age (especially insomnia), unemployment and marital status, urban residence and female gender [33Ogbolu 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): 1-5.
[http://dx.doi.org/10.4172/2167-0277.1000104]
, 34Yaya S, Wang R, Shangfeng T, Ghose B. Alcohol consumption and sleep deprivation among Ghanaian adults: Ghana Demographic and Health Survey. peer J 2018; 6: 1-14.].

Patients with sleep disturbances and poor sleep quality had a lower score on all domains of QOL and daytime dysfunction accounted for 12.6% of QOL index variance [35Ritsner M, Kurs R, Ponizovsky A, Hadjez J. Perceived quality of life in schizophrenia: Relationships to sleep quality. Qual Life Res 2004; 13(4): 783-91.
[http://dx.doi.org/10.1023/B:QURE.0000021687.18783.d6] [PMID: 15129888]
] and the score of QOL was reduced for patients with sleep disturbances [7Hofstetter JR, Lysaker PH, Mayeda AR. Quality of sleep in patients with schizophrenia is associated with quality of life and coping. BMC Psychiatry 2005; 5(13): 13.
[http://dx.doi.org/10.1186/1471-244X-5-13] [PMID: 15743538]
]. Schizophrenic patients with daytime dysfunction and insomnia had a lower score of physical and social domains of QOL and the score was also lower on most domains of QOL for patients with poor sleep quality [14Darchia N, Oniani N, Sakhelashvili I, et al. Relationship between sleep disorders and health related quality of life: Results from the Georgia Somnus study. Int J Environ Res Public Health 2018; 15(8): 1-15.
[http://dx.doi.org/10.3390/ijerph15081588] [PMID: 30049991]
]. It was also reported that at least 29% of schizophrenic patients had no sleep disturbances and for those with sleep disturbances, the score of HRQOL was decreased significantly on all domains [21Lee M, Choh AC, Demerath EW, et al. Sleep disturbance in relation to health-related quality of life in adults: the Fels Longitudinal Study. J Nutr Health Aging 2009; 13(6): 576-83.
[http://dx.doi.org/10.1007/s12603-009-0110-1] [PMID: 19536428]
], and patients with any sleep disturbance had decreased quality of life when compared with those without sleep disturbances [36Schubert CR, Cruickshanks KJ, Dalton DS, Klein BEK, Klein R, Nondahl DM. Prevalence of sleep problems and quality of life in an older population. Sleep 2002; 25(8): 889-93.
[PMID: 12489896]
].

It was reported as patients with prominent positive symptoms had higher daytime dysfunctions [37Tatari F. Habibolah Khazaie PP and LR. Sleep quality in patients with positive and negative symptoms of schizophrenia. Eur J Pers Cent Healthc 2018; 6(2): 257-61.
[http://dx.doi.org/10.5750/ejpch.v6i2.1443]
], and patients with more severe positive symptoms had worsened sleep disturbances than those with prominent negative symptoms [38Afonso P, Brissos S, Bobes J, Cañas F, Fernandez IB. Personal and social functioning and satisfaction with life in schizophrenia outpatients with and without sleep disturbances. J Ment Health 2015; 1(1): 33-40.
[PMID: 25587817]
]. However, another study reported as no significant difference was found between patients with prominent positive and negative symptoms concerning sleep quality and sleep disturbances except that patients with prominent negative symptoms had reported poor social functioning [39Afonso P, Brissos S, Figueira ML, Paiva T. Schizophrenia patients with predominantly positive symptoms have more disturbed sleep-wake cycles measured by actigraphy. Psychiatry Res 2011; 189(1): 62-6.
[http://dx.doi.org/10.1016/j.psychres.2010.12.031] [PMID: 21257208]
].

Concerning antipsychotic medications, olanzapine post-treatment patients had shown increased total sleep hours, increased sleep efficiency and decreased sleep latency [40Katshu MZUH, Sarkar S, Nizamie SH. Effect of Olanzapine on Clinical and Polysomnography Profiles in Patients with Schizophrenia. Schizophr Res Treatment 2018; 20183968015
[http://dx.doi.org/10.1155/2018/3968015] [PMID: 29675276]
] and literature also reported that typical antipsychotics had the effects of increasing sleep efficiency, stage 4 sleeps and decreased REM latency in a short-term administration and atypical antipsychotics showed the effects of increasing total sleep time and sleep efficiency except for risperidone which has no such effects [41Cohrs S. Sleep disturbances in patients with schizophrenia: Impact and effect of antipsychotics. CNS Drugs 2008; 22(11): 939-62.
[http://dx.doi.org/10.2165/00023210-200822110-00004] [PMID: 18840034]
]. It is also reported as atypical antipsychotics like olanzapine and risperidone have the ability to improve sleep quality in schizophrenic patients than typical antipsychotics [42Miller DD. Atypical antipsychotics: Sleep, sedation, and efficacy. Prim Care Companion J Clin Psychiatry 2004; 6(2)(Suppl. 2): 3-7.
[PMID: 16001094]
]. Although knowing the magnitude of sleep problems and their association with quality of life is vital to manage, the study was lacking in the current setting to our best knowledge. So, the current study is aimed to assess sleep disturbance and its association with quality of life among schizophrenic patients and try to fill gaps in the area.

2. MATERIALS AND METHODS

2.1. Study Design and Period

The current study is part of a previous study that was under process for publication elsewhere. It was a cross-sectional study conducted at Jimma University specialized teaching hospital, psychiatric clinic among 411 out-patient schizophrenia aged 18 years and above from April 21-June 20, 2019. The minimum number of required sample size for this study was determined by using the formula to estimate a single population proportion using the following assumptions.

Where; n= minimum sample required

ϖ Z α/2 = standard score value for 95% confidence level=1.96

ϖ P= Estimated prevalence of sleep disturbances in schizophrenic patients (taken as 50% since no published material was found in our country and comparable countries among the same subjects as far as searched).

ϖ d= is margin of error (5%)

Using the above assumptions; n = [(1.96)2 x 0.5 (1-0.5)] / (0.05)2 n= 384

By adding 10% (384 x 0.10 = 38) of non-respondent, the final sample size was (384+38) = 422 although the response rate was 97.4% and accordingly 411 patients were finally included for analysis. Participants were included by using consecutive sampling technique and data were collected by face to face interview using structured and pre-tested questionnaires and card review for diagnosis. Patients who were acutely disturbed and those with other psychiatric comorbidity were excluded.

2.2. Data Collection Instruments

Questionnaires have contained socio-demographic characteristics of the participants, tools to assess sleep pattern, quality of life and severity of psychotic symptoms.

Sleep disturbance was assessed by Pittsburgh Sleep Quality Index (PSQI), which is a highly used tool to measure seven domains: sleep duration, sleep disturbances and sleep latency, use of sleep medication, daytime dysfunction, habitual sleep efficiency, and subjective sleep quality over the last month. Sleep disturbance is assessed by using nine different questions, which have 0-3 score each. Participants who had scored at least one positive response were identified as had some sort of sleep disturbance and the severity of the disturbance is increased with the score [43Buysse DJ, Reynolds CF, Monk TH, Berman KD Sr. The Pittsburgh Sleep Quality Index (PSQI): A new instrument for psychiatric research and practice. Psychiatry Res 1989; 28: 193-213.
[http://dx.doi.org/10.1016/0165-1781(89)90047-4] [PMID: 2748771]
].

Quality of life was measured by the world health organization's quality of life scale-brief version (WHOQOL-Brief), which has 26 self-administered generic items. It is a valid tool cross-culturally and suitable to assess QOL in schizophrenic patients. The tool assesses four domains: physical health, psychological health, social relationships and environmental domain. Its score is a Likert form from 1 (very dissatisfied) to 5 (very satisfied) [44Hong AH, Sullivan FR. Towards an idea-centered, principle-base design to as creation approach support learning knowledge. Educ Technol Res Dev 2013; 57(5): 613-27.
[http://dx.doi.org/10.1007/s11423-009-9122-0]
, 45Orley J. WHOQOL-BREF: Introduction, administration and generic version 1996; 1-4.].

The severity of psychotic symptoms (positive, negative and general psychopathology) of schizophrenia was assessed by the Positive and negative syndrome scale (PANSS), which is a 7-point rating instrument and contains 30-items grouped into P1-P7, N1-N7 and G1-G16 [46Santor DA, Ascher-Svanum H, Lindenmayer JP, Obenchain RL. Item response analysis of the positive and negative syndrome scale. BMC Psychiatry 2007; 7(66): 66.
[http://dx.doi.org/10.1186/1471-244X-7-66] [PMID: 18005449]
].

2.3. Data Quality Control

Forth and back translation of English versions questionnaires to local language (Amharic) was conducted. The pretest was done to clarify the difficulty of data collection instruments and collected data were checked for clearness and consistency on daily bases.

2.4. Data Processing and Analysis

Data were entered into Epi data version 3.1 and analyzed by SPSS version 23.0. Chi-square test was used for the association of sleep disturbance and categorical variables. Cramer’s V test was considered for effect size. For continuous variables, independent samples t-test was employed to calculate the mean difference and eta squared was considered to evaluate effect size by considering the quality of life as an outcome variable. We considered these methods rather than multivariate regression as we included view variables to consider the specific relationship between sleep disturbances and quality of life. Overall, 95% confidence interval and p-value < 0.05 was considered for statistical significance.

All assumptions were checked accordingly and Hosmer and Lameshow were calculated to check model fitness.

3. RESULTS

Finally, 411(97.4%) participants were included in the analysis and the majority (70.6%) of them were male. Almost half (49.5%) of the study subjects were currently living in urban residence. From the total participants, about one-third of them were followed only by primary school and 25.5% of study subjects were never married (Table 1).

In general, most (71.3%) of the patients had reported sleep disturbances and more than one-third of them slept for more than 7 hours/day during the past month. Slightly about one-fourth of the patients had reported very good subjective sleep quality and > 85% sleep efficiency was reported by 139 (33.8%) generally. More than half (51.1%) of participants had used any sleep medication in the past month and majority (64.7%) of study subjects were reported daytime dysfunction. (Table 2)

Table 1
Socio-demographic characteristics of patients with schizophrenia at Jimma University medical center, 2019 (n=411).


Table 2
Score on PSQI for patients with schizophrenia at Jimma University medical center, 2019 (n=411).


On PANSS measure, the mean score for the negative scale was relatively lower than that of a positive scale and for the WHOQOL scale, the participants had scored lower on social and psychological domains and overall WHOQOL score.

On the chi-square test, both male and female had almost the same percentage for sleep disturbance, while subjects between the ages of 45-64 had a higher (74.9%) proportion than those between the ages of 18-44 (68.4%). On the other hand, the current place of residence had significantly associated with sleep disturbance and the proportion of urban participants who had reported sleep disturbance was higher than that of rural respondents and participants who reported greater than mean on a positive scale had a moderately strong association when Cramer’s V-test was considered. (Table 3).

For continuous variables, an independent samples t-test was conducted to compare the mean score of WHOQOL domains and PANSS score for participants with and without sleep disturbances. The magnitude of the difference in the mean was considered by calculating eta squared and interpreted as Cohen guidelines (0.01= small effect, 0.06 = moderate effect and 0.14 = strong effect) [48Cohen J. Statistical Power Analysis for the Behavioral Sciences. J Am Stat Assoc 1989; 84(408): 1096.
[http://dx.doi.org/10.2307/2290095]
]. Accordingly, social domain (M±SD=3.92±2.51, t=8.46, p= <0.001, eta2=0.15) and overall WHOQOL (M±SD=57.60±16.87, t=9.24, p= < 0.001, eta2= 0.17) the score had a large difference in their means and about 15% and 17% of the variance in sleep disturbance have been explained by social domain and overall WHOQOL score, respectively. On the PANSS score, the positive scale showed a moderate effect in mean difference while negative and general psychopathology had little effects (Table 4).

Table 3
Chi-square score of categorical variables in relation to sleep disturbance among patients with schizophrenia at Jimma University medical center, 2019 (n=411).


Table 4
Independent samples t-test for comparisons of means for WHOQOL and PANSS score on sleep disturbances for patients with schizophrenia at Jimma University medical center, 2019 (n=411).


4. DISCUSSION

In the current cross-sectional study, the majority (71.3%) of the participants with 95% CI: [67.2, 75.9] had sleep disturbances in general. This finding was in line with the previous study [28Waters F, Manoach DS. Sleep dysfunctions in schizophrenia : A practical review. Open J Psychiatr 2012; 2: 384-92.
[http://dx.doi.org/10.4236/ojpsych.2012.224054]
] may be due to comparable sample size and the same study design. However, the current finding was lower than the reported results from different studies [4Laskemoen JF, Simonsen C, Büchmann C, et al. Sleep disturbances in schizophrenia spectrum and bipolar disorders - a transdiagnostic perspective. Compr Psychiatry 2019; 91: 6-12.
[http://dx.doi.org/10.1016/j.comppsych.2019.02.006] [PMID: 30856497]
, 5Waite F, Sheaves B, Isham L, Reeve S, Freeman D. Sleep and schizophrenia: From epiphenomenon to treatable causal target. Schizophr Res 2019; xxxx(xxxx): 1-13., 23de Niet GJ, Tiemens BG, Lendemeijer HH, Hutschemaekers GJ, Hutschemaekers G. Perceived sleep quality of psychiatric patients. J Psychiatr Ment Health Nurs 2008; 15(6): 465-70.
[http://dx.doi.org/10.1111/j.1365-2850.2008.01250.x] [PMID: 18638206]
]. This may be reasoned by the difference in assessment tools, study settings, differences in study design and inclusion criteria.

In this study, the proportion of participants with sleep disturbance was significantly higher in urban residents than rural residents. This is in agreement with the previous study, which reported that the participants from the urban residence had a shorter sleep time, more sleep disturbance and poorer sleep quality [49Med E, Investigation O. Sleep quality and factors affecting it in patients with chronic psychiatric disorders. Erciyes Med J 2015; 37(1): 6-10.
[http://dx.doi.org/10.5152/etd.2015.7837]
].

In our study, on the WHOQOL score, the means of psychological and social domains significantly differ for participants with sleep disturbance and without sleep disturbance, which accounted for about 13% and 15% of the variance, respectively. This is in line with the study conducted previously in which participants with sleep disturbances had a lower score of QOL on all domains and accounted for 12.6% of the variance. It also reported that the overall score of QOL reduced for patients with sleep disturbance and accounts for about 24% of the variance [7Hofstetter JR, Lysaker PH, Mayeda AR. Quality of sleep in patients with schizophrenia is associated with quality of life and coping. BMC Psychiatry 2005; 5(13): 13.
[http://dx.doi.org/10.1186/1471-244X-5-13] [PMID: 15743538]
, 35Ritsner M, Kurs R, Ponizovsky A, Hadjez J. Perceived quality of life in schizophrenia: Relationships to sleep quality. Qual Life Res 2004; 13(4): 783-91.
[http://dx.doi.org/10.1023/B:QURE.0000021687.18783.d6] [PMID: 15129888]
]. Another cross-sectional study revealed the same result in which participants with sleep disturbance like daytime dysfunction and insomnia had a lower score on psychological and social domains of WHOQO [14Darchia N, Oniani N, Sakhelashvili I, et al. Relationship between sleep disorders and health related quality of life: Results from the Georgia Somnus study. Int J Environ Res Public Health 2018; 15(8): 1-15.
[http://dx.doi.org/10.3390/ijerph15081588] [PMID: 30049991]
].

Like the current study, the previous studies reported that participants with sleep disturbances had significantly decreased HRQOL score on all domains and patients with sleep disturbances have shown overall lowered quality of life [36Schubert CR, Cruickshanks KJ, Dalton DS, Klein BEK, Klein R, Nondahl DM. Prevalence of sleep problems and quality of life in an older population. Sleep 2002; 25(8): 889-93.
[PMID: 12489896]
].

Cross-sectional nature of the current study was identified as one limitation as it cannot explain the cause-effect relationship. The other possible limitation of this study was that we did not perform an objective assessment of sleep parameters by actigraphy and sleep laboratory. Despite these limitations, the current findings will be used as a baseline for future studies and help in giving evidence-based care among people with schizophrenia.

CONCLUSION

Generally, in this study, we identified that the prevalence of sleep disturbance was high among schizophrenic patients and it affects different domains in a patient’s quality of life and need great attention from treating clinicians and administrative bodies.

LISTS OF ABBREVIATIONS

G  = General
HRQOL  = Health-related Quality of Life
N  = Negative
P  = Positive
PANSS  = Positive and Negative Syndrome Scale
PSQI  = Pittsburgh Sleep Quality Index
WHOQOL-BREF  = WHO Quality of Life Brief Version

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

Ethical clearance was obtained from the ethical review board of Institute of Health, Jimma University, Ethiopia with reference number JHRPGD/608/2019.

HUMAN AND ANIMAL RIGHTS

Not applicable.

CONSENT FOR PUBLICATION

Data were collected after written consent was obtained and any personal information was kept entirely confidential and participants were assessed in a private room to maintain their privacy.

AVAILABILITY OF DATA AND MATERIALS

The data supporting the findings are available with the corresponding author and can be availed on a necessary request.

FUNDING

The financial need for data collection was fulfilled by the Mettu University.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interest regarding this project and they approved it for publication.

ACKNOWLEDGEMENTS

We would like to acknowledge the psychiatric clinic staff of Jimma University for their great cooperation, Mettu University, for providing financial support and all our study participants.

REFERENCES

[1] Benjamin J. Sadock MD, Virginia A. Sadock MD, Pedro R. MD. Synopsis of psychiatry behavioral sciences/clinical psychiatry 11th edt. 2015; 649-52.
[2] Pritchett D, Wulff K, Oliver PL, et al. Evaluating the links between schizophrenia and sleep and circadian rhythm disruption. J Neural Transm (Vienna) 2012; 119(10): 1061-75.
[http://dx.doi.org/10.1007/s00702-012-0817-8] [PMID: 22569850]
[3] Ered A, Cooper S, Ellman LM. Sleep quality, psychological symptoms, and psychotic-like experiences. J Psychiatr Res 2018; 98(98): 95-8.
[http://dx.doi.org/10.1016/j.jpsychires.2017.12.016] [PMID: 29331930]
[4] Laskemoen JF, Simonsen C, Büchmann C, et al. Sleep disturbances in schizophrenia spectrum and bipolar disorders - a transdiagnostic perspective. Compr Psychiatry 2019; 91: 6-12.
[http://dx.doi.org/10.1016/j.comppsych.2019.02.006] [PMID: 30856497]
[5] Waite F, Sheaves B, Isham L, Reeve S, Freeman D. Sleep and schizophrenia: From epiphenomenon to treatable causal target. Schizophr Res 2019; xxxx(xxxx): 1-13.
[6] Ered A, Cooper S, Ellman LM. Sleep quality, psychological symptoms, and psychotic-like experiences. J Psychiatr Res 2018; 98: 95-8.
[http://dx.doi.org/10.1016/j.jpsychires.2017.12.016] [PMID: 29331930]
[7] Hofstetter JR, Lysaker PH, Mayeda AR. Quality of sleep in patients with schizophrenia is associated with quality of life and coping. BMC Psychiatry 2005; 5(13): 13.
[http://dx.doi.org/10.1186/1471-244X-5-13] [PMID: 15743538]
[8] Wubeshet YS, Mohammed OS, Desse TA. Prevalence and management practice of first generation antipsychotics induced side effects among schizophrenic patients at Amanuel Mental Specialized Hospital, central Ethiopia: cross-sectional study. BMC Psychiatry 2019; 19(1): 32.
[http://dx.doi.org/10.1186/s12888-018-1999-x] [PMID: 30658604]
[9] Eticha T, Teklu A, Ali D, Solomon G, Alemayehu A. Factors associated with medication adherence among patients with schizophrenia in Mekelle, Northern Ethiopia. PLoS One 2015; 10(3)e0120560
[http://dx.doi.org/10.1371/journal.pone.0120560] [PMID: 25816353]
[10] Theofilou P. Quality of life: Definition and measurement. Eur J Psychol 2013; 9(1): 150-62.
[http://dx.doi.org/10.5964/ejop.v9i1.337]
[11] Hasan M, Mahmud S, Yeasmin B, Mandal S. Quality of life of schizophrenic patients in a tertiary care hospital in Bangladesh. Bang J Psychiatry 2015; 29(1): 30-4.
[12] Chaturvedi SK, Muliyala KP. The Meaning in Quality of Life. J Psychosoc Rehabil Ment Health 2016; 3(2): 47-9.
[http://dx.doi.org/10.1007/s40737-016-0069-2]
[13] Azaiez C, Millier A, Lançon C, et al. Health related quality of life in patients having schizophrenia negative symptoms - a systematic review. J Mark Access Health Policy 2018; 6(1)1517573
[http://dx.doi.org/10.1080/20016689.2018.1517573] [PMID: 30275939]
[14] Darchia N, Oniani N, Sakhelashvili I, et al. Relationship between sleep disorders and health related quality of life: Results from the Georgia Somnus study. Int J Environ Res Public Health 2018; 15(8): 1-15.
[http://dx.doi.org/10.3390/ijerph15081588] [PMID: 30049991]
[15] Peltzer K, Pengpid S. Self-reported sleep duration and its correlates with sociodemographics, health behaviours, poor mental health, and chronic conditions in rural persons 40 years and older in South Africa. Int J Environ Res Public Health 2018; 15(7): 1-9.
[http://dx.doi.org/10.3390/ijerph15071357] [PMID: 29958407]
[16] Kim TK, Lee HC, Lee SG, Han KT, Park EC, Park E. The combined effect of sleep duration and quality on mental health among Republic of Korea armed forces. Mil Med 2016; 181(11): e1581-9.
[http://dx.doi.org/10.7205/MILMED-D-15-00538] [PMID: 27849493]
[17] Sutton EL. Psychiatric disorders and sleep issues. Med Clin North Am 2014; 98(5): 1123-43.
[http://dx.doi.org/10.1016/j.mcna.2014.06.009] [PMID: 25134876]
[18] Winsky-Sommerer R, de Oliveira P, Loomis S, Wafford K, Dijk DJ, Gilmour G. Disturbances of sleep quality, timing and structure and their relationship with other neuropsychiatric symptoms in Alzheimer’s disease and schizophrenia: Insights from studies in patient populations and animal models. Neurosci Biobehav Rev 2019; 97: 112-37.
[http://dx.doi.org/10.1016/j.neubiorev.2018.09.027] [PMID: 30312626]
[19] Van Den Noort M, Staudte H, Perriard B, Yeo S, Lim S, Bosch P. Schizophrenia and comorbid sleep disorders. Neuroimmunol Neuroinflamm 2016; 3: 225-7.
[http://dx.doi.org/10.20517/2347-8659.2016.42]
[20] Sahin NH. Specific Quality of Life Measures for Sleep Disorders https//www.researchgate.net/publication/2219286272014.
[21] Lee M, Choh AC, Demerath EW, et al. Sleep disturbance in relation to health-related quality of life in adults: the Fels Longitudinal Study. J Nutr Health Aging 2009; 13(6): 576-83.
[http://dx.doi.org/10.1007/s12603-009-0110-1] [PMID: 19536428]
[22] Kia Byrd, Bizu Gelaye, Mahlet G. Tadessea, Michelle A. Williams, Seblewengel Lemma and YB. Sleep Disturbances and Common Mental Disorders in College Students. Health Behav Policy Rev 2014; 1(3): 229-37.
[http://dx.doi.org/10.14485/HBPR.1.3.7] [PMID: 25309939]
[23] de Niet GJ, Tiemens BG, Lendemeijer HH, Hutschemaekers GJ, Hutschemaekers G. Perceived sleep quality of psychiatric patients. J Psychiatr Ment Health Nurs 2008; 15(6): 465-70.
[http://dx.doi.org/10.1111/j.1365-2850.2008.01250.x] [PMID: 18638206]
[24] Wulff K, Dijk DJ, Middleton B, Foster RG, Joyce EM. Sleep and circadian rhythm disruption in schizophrenia. Br J Psychiatry 2012; 200(4): 308-16.
[http://dx.doi.org/10.1192/bjp.bp.111.096321] [PMID: 22194182]
[25] Afonso P, Figueira ML, Paiva T. Sleep-wake patterns in schizophrenia patients compared to healthy controls. World J Biol Psychiatry 2014; 15(7): 517-24.
[http://dx.doi.org/10.3109/15622975.2012.756987] [PMID: 23316764]
[26] Monti JM, BaHammam AS, Pandi-Perumal SR, et al. Sleep and circadian rhythm dysregulation in schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2013; 43: 209-16.
[http://dx.doi.org/10.1016/j.pnpbp.2012.12.021] [PMID: 23318689]
[27] Campos EDM, Melo CM, Maia WS, Felipe P, De Bruin C, Ponte L, et al. Sleep disturbances and gender differences in schizophrenia. Sleep Sci 2008; 1(9): 27-30.
[28] Waters F, Manoach DS. Sleep dysfunctions in schizophrenia : A practical review. Open J Psychiatr 2012; 2: 384-92.
[http://dx.doi.org/10.4236/ojpsych.2012.224054]
[29] Waite F, Evans N, Myers E, et al. The patient experience of sleep problems and their treatment in the context of current delusions and hallucinations. Psychol Psychother 2016; 89(2): 181-93.
[http://dx.doi.org/10.1111/papt.12073] [PMID: 26285922]
[30] Ma XR, Song GR, Xu XB, Tian T, Chang SH, Cdo DS. The Prevalence of Sleep Disturbance and Its Socio-demographic and Clinical Correlates in First-episode Individuals With Schizophrenia in Rural China. Perspect Psychiatr Care 2018; 54(1): 31-8.
[http://dx.doi.org/10.1111/ppc.12197] [PMID: 27861956]
[31] Subramaniam M, Abdin E, Shahwan S, et al. Prevalence, correlates and outcomes of insomnia in patients with first episode psychosis from a tertiary psychiatric institution in Singapore. Gen Hosp Psychiatry 2018; 51: 15-21.
[http://dx.doi.org/10.1016/j.genhosppsych.2017.11.009] [PMID: 29268166]
[32] Lemola S, Ledermann T, Friedman EM. Variability of sleep duration is related to subjective sleep quality and subjective well-being: an actigraphy study. PLoS One 2013; 8(8)e71292
[http://dx.doi.org/10.1371/journal.pone.0071292] [PMID: 23967186]
[33] 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): 1-5.
[http://dx.doi.org/10.4172/2167-0277.1000104]
[34] Yaya S, Wang R, Shangfeng T, Ghose B. Alcohol consumption and sleep deprivation among Ghanaian adults: Ghana Demographic and Health Survey. peer J 2018; 6: 1-14.
[35] Ritsner M, Kurs R, Ponizovsky A, Hadjez J. Perceived quality of life in schizophrenia: Relationships to sleep quality. Qual Life Res 2004; 13(4): 783-91.
[http://dx.doi.org/10.1023/B:QURE.0000021687.18783.d6] [PMID: 15129888]
[36] Schubert CR, Cruickshanks KJ, Dalton DS, Klein BEK, Klein R, Nondahl DM. Prevalence of sleep problems and quality of life in an older population. Sleep 2002; 25(8): 889-93.
[PMID: 12489896]
[37] Tatari F. Habibolah Khazaie PP and LR. Sleep quality in patients with positive and negative symptoms of schizophrenia. Eur J Pers Cent Healthc 2018; 6(2): 257-61.
[http://dx.doi.org/10.5750/ejpch.v6i2.1443]
[38] Afonso P, Brissos S, Bobes J, Cañas F, Fernandez IB. Personal and social functioning and satisfaction with life in schizophrenia outpatients with and without sleep disturbances. J Ment Health 2015; 1(1): 33-40.
[PMID: 25587817]
[39] Afonso P, Brissos S, Figueira ML, Paiva T. Schizophrenia patients with predominantly positive symptoms have more disturbed sleep-wake cycles measured by actigraphy. Psychiatry Res 2011; 189(1): 62-6.
[http://dx.doi.org/10.1016/j.psychres.2010.12.031] [PMID: 21257208]
[40] Katshu MZUH, Sarkar S, Nizamie SH. Effect of Olanzapine on Clinical and Polysomnography Profiles in Patients with Schizophrenia. Schizophr Res Treatment 2018; 20183968015
[http://dx.doi.org/10.1155/2018/3968015] [PMID: 29675276]
[41] Cohrs S. Sleep disturbances in patients with schizophrenia: Impact and effect of antipsychotics. CNS Drugs 2008; 22(11): 939-62.
[http://dx.doi.org/10.2165/00023210-200822110-00004] [PMID: 18840034]
[42] Miller DD. Atypical antipsychotics: Sleep, sedation, and efficacy. Prim Care Companion J Clin Psychiatry 2004; 6(2)(Suppl. 2): 3-7.
[PMID: 16001094]
[43] Buysse DJ, Reynolds CF, Monk TH, Berman KD Sr. The Pittsburgh Sleep Quality Index (PSQI): A new instrument for psychiatric research and practice. Psychiatry Res 1989; 28: 193-213.
[http://dx.doi.org/10.1016/0165-1781(89)90047-4] [PMID: 2748771]
[44] Hong AH, Sullivan FR. Towards an idea-centered, principle-base design to as creation approach support learning knowledge. Educ Technol Res Dev 2013; 57(5): 613-27.
[http://dx.doi.org/10.1007/s11423-009-9122-0]
[45] Orley J. WHOQOL-BREF: Introduction, administration and generic version 1996; 1-4.
[46] Santor DA, Ascher-Svanum H, Lindenmayer JP, Obenchain RL. Item response analysis of the positive and negative syndrome scale. BMC Psychiatry 2007; 7(66): 66.
[http://dx.doi.org/10.1186/1471-244X-7-66] [PMID: 18005449]
[47] Nations U. Provisional guidelines on standard international age classifications 1982; 31.
[48] Cohen J. Statistical Power Analysis for the Behavioral Sciences. J Am Stat Assoc 1989; 84(408): 1096.
[http://dx.doi.org/10.2307/2290095]
[49] Med E, Investigation O. Sleep quality and factors affecting it in patients with chronic psychiatric disorders. Erciyes Med J 2015; 37(1): 6-10.
[http://dx.doi.org/10.5152/etd.2015.7837]
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