Sleep disturbance affects 50% – 80% of all patients with psychiatric disorders and can be both a cause and effect of the same.¹ Epidemiological data from Western studies show that 0.047% – 50.5% of the general population suffer from sleep disorders.² There is a downward trend in average sleep duration and an increasing prevalence of sleep disturbances.^2,3 A significant cost burden is solely attributed to sleep problems, and this is likely to increase exponentially in the coming years. These costs are both direct (treatment costs) and indirect (absenteeism, decreased productivity, accidents, etc.) costs.³ Sleep disturbance is one of the features of mood, anxiety and some personality disorders, and is often bidirectional.^4,5 Insomnia is seen in more than 90% of patients with clinical depression. Insomnia as a symptom has a 60% – 70% positive predictive value in diagnosing major depressive disorder.^2,6 To date, most research has focussed more on sleep in depression than in any other psychiatric disorder.⁷ However, rapid eye movement (REM) sleep abnormalities have been illustrated in schizophrenia,^8,9 alcohol use disorder, eating disorder and in borderline personality disorder.¹⁰

Sleep is defined as a rapidly reversible state with decreased awareness of external stimuli.¹¹ It comprises several defined stages and is assessed in research by electrophysiological changes and with behavioural observation.¹¹ Sleep is a universal need among species, yet the exact functions of sleep are still poorly understood. Loss of sleep, however, leads to emotional, cognitive and even physical impairment, as several sleep deprivation studies have shown.¹²

Historically, scholars in psychiatry, dating back to Sigmund Freud and Carl Jung in the 19th century, had a special interest in sleep, dreams and their relationship with mental illness.¹³ Sleep monitoring and research began as early as 1929, pioneered by Hans Berger, and by the 1970s, sleep disorders were characterised and diagnosed.¹¹ Several hypotheses exist postulating the functions of sleep, but all the known facts of sleep fail to be accounted for under any one hypothesis. Broadly, current research into the functions of sleep shows a role in restoration of metabolic function and/or in serving mechanisms involved in neural plasticity.¹¹

The duration of sleep obtained per night varies across the human lifespan. Natural variation of this occurs with inherently short sleepers and long sleepers. Sleep needs and patterns are influenced by several factors, including genetic factors, age, and comorbid medical and psychiatric disorders.¹¹ Alteration in sleep architecture also occurs over time for example the significantly diminished amount of slow wave sleep seen during adolescence. One theory by Irwin Feinberg relates this with synaptic pruning at this stage.¹¹ Abnormal synaptic pruning may account for the timing of the peak in incidence seen in schizophrenia in late adolescence and early adulthood.^14,15 This suggests that the systems involved in sleep and wakefulness overlap significantly with emotional regulation and other behaviours.¹¹ It is thus not surprising that sleep abnormalities are common in patients with psychiatric disorders, part of the diagnostic criteria of these disorders, and appear to have some predictive value for the trajectory of these disorders.⁴ Furthermore, many psychotropic medications used in the management of psychiatric disorders have both positive and negative effects on sleep.²

Örsal et al.¹⁶ defined sleep quality as ‘the efficiency of sleep’. It consists of several components: subjective sleep quality, delay to onset, duration, habitual sleep activity, primary sleep disorder, daytime dysfunction and use of opiates or sedatives. Harvey et al.¹⁷ proposed a two-way neurobiological relationship between sleep disturbances and emotional regulation, and how they are linked in psychiatric disorders, that is, that a functional relationship exists between sleep and mood.^17,18 Sleep deprivation has an antidepressant-like effect, possibly by normalising the accelerated metabolic activity in the anterior cingulate gyrus seen in people with depression and anxiety disorders,¹⁰ which is reversed by even a short bout of sleep.

This suggests an ability for sleep loss to precipitate and perpetuate mania, and possibly other psychiatric symptoms.¹⁷ However, the exact causal link between health outcomes and sleep is still unclear, and controversial, and further longitudinal studies are essential.

Sleep deprivation studies in recent decades have revealed cognitive impairment, specifically, deficits in attention and short-term memory, impairment in speech, perseveration and concrete thinking.¹⁹ There is also an effect on emotional reactivity and processing of emotional information.²⁰ Sleep deprivation may also impact on various physiological systems which may affect overall health, that is, by affecting host defences, impairing glucose tolerance, autonomic hyperarousal and increasing cortisol – which has implications for various chronic systemic disorders.¹¹ These findings suggest an important correlation between sleep quality and health outcomes overall.

An association also exists between sleep disturbances and subjective benefit from treatment received, and thus, the patient’s overall perceived quality of life.¹ Sleep disturbance also impacts objective assessment of disease severity and functioning, and has also shown to be the most common residual symptom after successful treatment of major depressive disorder.¹

Sleep disorders and psychiatric disorders are recognised as bi-directional in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).^1,4,21 Assessing sleep quality in those in remission from the core symptoms of psychiatric disorders, can help to identify the likelihood of under diagnosis of concomitant primary sleep disorders and possible treatment thereof.^1,22 There is a paucity of evidence of sleep quality assessment in psychiatric disorders other than depression, and sleep quality directly affects the adaptation of patients to the disorder and their commitment to participating in the treatment process. This shift in thinking and greater awareness of sleep problems could assist with early recognition and management of sleep disorders, subsequently impacting on the trajectory of the disorder and remission rates, overall prognosis and quality of life.¹ Thus, the aim of this research study was to assess the overall sleep quality of psychiatric outpatients at Chris Hani Baragwanath Academic Hospital (CHBAH), using the Pittsburgh Sleep Quality Index (PSQI), and to link this with their socio-demographic variables.

The data set included a total of 90 participants (excluding the one repeat participant whose data are not considered in the analyses) at the psychiatric OPD at CHBAH. Missing data (two incomplete questionnaires) are excluded in the analyses, below, so sample sizes varied.

This study was conducted at CHBAH adult OPD from March to June 2021. The number of patients serviced by the OPD lessened during the coronavirus disease 2019 (COVID-19) pandemic due to safety protocols and alteration of the number of patients booked per day. Due to the diversity of patients seen, and rigorous inclusion and exclusion criteria, only 90 patients of the total population seen at OPD were eligible for participation in the study during the study period. Because of the decrease in overall numbers seen, this led to a smaller sample size than initially anticipated.

The key findings included 50% of participants having an overall PSQI score of ≥5 and thus, poor sleep quality. This is in line with previous research placing this figure at 50% – 80% of patients with psychiatric disorders.¹ The rigorous exclusion criteria, which excluded confounding factors such as medical conditions, active substance use and mental disorders not in remission, may account for this figure being on the lower end compared to existing research. There was no significant association between sex and age as predictors of sleep quality.

Although not significant, female participants had poorer sleep quality than male participants overall (Figure 2). Shift work (two participants) and being the primary caregiver to children under 6 years of age (one participant) were not significant predictors of sleep quality, likely due to the small data set. Although other forms of employment were not considered in this study, the presence of only two participants who did shift work could be representative of the burden of unemployment in the country (28.91%),²⁹ which was worsened by job losses associated with the COVID-19 pandemic. Stigma, which still plays a role, may be an important contributing factor to the higher rates of unemployment in people living with mental illness.³⁰

The diagnoses of the participants included some overlap with comorbid disorders, which are listed separately (Table 3), but broadly included: bipolar and related disorders (25 participants); depressive disorders²⁸; schizophrenia spectrum and other psychotic disorders²⁹; schizoaffective disorder⁵; obsessive-compulsive and related disorders¹; trauma- and stressor-related disorders⁵; anxiety disorders⁷; substance use disorders – in remission¹⁷; personality disorders – cluster B¹² and cluster C²; other.⁴. Mood disorders accounted for 58.9% and psychotic disorders accounted for 36.7% of the total participants, probably because mood disorders are more prevalent than psychotic disorders in the population. Although anxiety disorders are most prevalent in the general population,³¹ it is unlikely that people with this disorder alone would primarily be managed at a tertiary level institution, hence their absence from the data set.

Of the participants reporting poor overall sleep quality, 27 participants had mood disorders (50.9%), 3 had anxiety disorders that were comorbid (42.8%) and 13 had psychotic disorders (39.4%). Most previous research has focused on sleep in depression compared to other psychiatric disorders,⁷ so this finding of poor sleep predominantly in people with mood disorders is consistent with previous studies, suggesting that a functional relationship exists between sleep and psychiatric disorders, and more so, with mood disorders.^17,18 Poor sleep quality has also been shown to impair emotional regulation.²⁰

There is some value in examining the subscales rather than just the overall PSQI score.²³ Some subscale findings are associated with emotional reactivity, emotional information processing and outcomes such as suicidality and positive affect – namely sleep duration and sleep efficiency.²⁰ For example, from the results of sleep deprivation studies, sleep duration may be expected to impact emotional reactivity.²⁰ Subscale 3 represents sleep duration. Thirteen participants (14.8%) had a score of 2–3 indicating sleep of less than 6 h. Sleep efficiency, which is a proxy for REM sleep and assesses time asleep vs. time in bed, was assessed on subscale 4. This showed an efficiency of <85% (score of >0) in 23 participants (26.4%). Sleep efficiency is associated with emotional information processing performance.²⁰ Sleep disturbances (frequency of disruptions during the night), which are common in depression,²⁰ were represented on subscale 5. Eighty-six participants (96.6%) reported sleep disturbances once or more per week. This may have an impact on daytime dysfunction (represented by subscale 7) and is associated with poorer performance in processing of emotional information.²⁰ Fifty-three participants (59.6%) reported varying daytime dysfunction in activities such as staying awake while driving, eating meals, or engaging in social activities, as well as less enthusiasm in getting things done (from the PSQI). Of note, 34 participants (38%) reported use of medicines (including over-the-counter formulations) for sleep (subscale 6).

Of the participants, 26 were on medicines prescribed for sleep from the OPD, namely Promethazine (15 participants), Amitriptyline (2 participants) and Quetiapine IR 25 mg – 150 mg (9 participants), for its sedative properties at this dose.³² Interestingly, none of the participants enrolled in the study were prescribed or reported using benzodiazepines, and almost all the participants on sleep medicines had a mood disorder diagnosis (19 participants). However, none of these participants were diagnosed with a comorbid sleep disorder. This may have been because of the type of participants included in the study, those that were in remission from symptoms of mental illness at the time of the study and thus, have less need for these medicines. The role of education of prescribers regarding the risks of long-term benzodiazepine use and working under supervision may also be contributory.

Poor sleep quality was found in half of the study participants irrespective of socio-demographic factors, medication type, psychiatric diagnosis and being in remission from symptoms. This suggests there is value in conceptualising sleep disturbances as a comorbid condition and managing it accordingly.