Sleep is an important physiological process with many restorative functions. It is essential in maintaining the body’s circadian rhythm and one of the basic needs of human beings [1-3]. Sleep disorder is a common problem in adults and affects physical and mental health [2, 3]. Poor sleep quality, often referred to as “sleep disturbance”, is found in up to 55% of the elderly population and consistently increases with age [1]. In fact, one in four people experiences sleep difficulties, which include trouble falling asleep, trouble staying asleep, early morning waking, sleeping too much, or restless or unsatisfying sleep [4]. Today, poor sleep quality among adolescents is becoming a major worldwide concern and is widely recognized as a significant public health problem [5].

The prison environment is one of the main challenges to the overall health of prisoners [6]. In prison, communication and relationship with families and friends also restricted. It's understandable that anybody in prison would be generally affected by poor quality of sleep. Around a third of the general population experiences insomnia at some point in their lives; however, recent figures show prisoners are at least twice as likely to have insomnia and the majorities have poor sleep quality [7]. This is problematic because insomnia has been shown to significantly contribute to poor cognitive functioning, depression, suicide, emotional deregulation, aggression and lack of treatment engagement, all of which may affect the safe running of the prison, an individual’s rehabilitation and, ultimately, the likelihood of reoffending [8].

Majority of the prisoners are kept in groups in a cell and are made to sleep on the floor, which is one of the main sources of infectious diseases [6]. In most prisons, prisoners often lack space to sleep or sit, hygiene is poor, and food and clothing are inadequate, and also forced to work when sick [9, 10].

Furthermore, the prison experience can be inherently stressful, which can contribute to insomnia. For example, prisoners experience a complete upheaval of normal life, family and routine forced contact with others and lack of autonomy, all of which can augment the stressful experience. Moreover, poor sleep hygiene, including daytime naps, boredom or paucity of daytime activity, is evident in prisoners [11]. Availing sleep management options in prison offers the potential to impact positively on a number of these common risk factors [8].

Very little research has been conducted on poor sleep quality in prison internationally. A study conducted on insomnia management in prisons in England and Wales reported prevalence rates from 11 to 81% [11]. Another study completed in maximum security women's prison in the United States indicates that 72% of the sample met the criteria for poor sleepers [12]. A cross-sectional study of the prevalence and associated risk factors of insomnia in adult prison populations in England reported an 88.2% rate of poor sleep quality [7]. Researchers at the UK’s University of Warwick Medical School conducted large-scale, multinational study of sleep disorders among eight countries in Asia and Africa which showed an overall rate of nearly 17% of the populations in these developing nations suffering from sleep problems [13]. The overall prevalence rate of insomnia among a mostly male population housed in a Swiss remand prison was 44% [12]. One study in China on the prevalence and risk factors of poor sleep quality among Chinese elderly in an urban community showed rates of self-reported insomnia ranging between 10% and 48% [14]. Another study conducted on bullying as a risk for poor sleep quality among high school students in China revealed that the number of adolescents involved in poor sleep quality worldwide varies between 18.7% and 25% [15].

One study among undergraduate students reported 16 to 67% having poor sleep quality(16). Other studies in Taiwan and Hong Kong Chinese reported the prevalence of poor sleep quality ranging from 6% to 78% [14]. In Mainland China, there was only one epidemiological study, reporting that 50% of elderly aged 60 or older had poor sleep quality in a sample population in rural areas [14]. One study done in primary health care revealed that poor sleep quality was present in 38.0% of total subjects [2]. Among Malaysian adults aged 30 to 70 years in four urban areas in Selangor, the prevalence of poor sleep quality with symptoms of insomnia was 33.8%, with 12.2% of them reported to have chronic insomnia [16]. A study in Malaysia on prevalence and factors associated with poor sleep quality among secondary school teachers in a developing country revealed the prevalence of poor sleep quality was 61% [16].

One study done among school students in Malaysia showed the prevalence of poor sleep quality was 24.0% (5). A study of the factors associated with poor sleep among medical students has been estimated to be 15% to 35% (17). The other study conducted among communities in Ethiopia showed that the overall prevalence of poor sleep quality was 65.4% [3].

The known risk factors of insomnia include female sex [1, 2, 11, 16], old age [2, 5, 9, 15], depression, snoring, low level of physical activity, the presence of underlying disease, low education level and economic status, living alone and stress [2, 14, 15, 17]. Chronic medical illnesses, depression, substance use, having lower levels of emotional support or being single, divorced or widowed, psychosocial factors and psychological influences are important factors that affect sleep quality [1, 2, 11, 14, 16-21]. For some prisoners, “guilt” and “shame” over criminal actions also contributed to poor sleep [12].

This study revealed an overall prevalence of poor sleep quality was nearly seven in every nine (77.1%). History of previous incarceration, marital status, urban in residence, educational status and lifetime alcohol use had significant association with poor sleep quality.

The finding of this study showed that the prevalence of poor sleep quality among prisoners in Mettu town prisoners was 77.1%. The finding was in line with studies carried out in England and Wales, where the prevalence of poor sleep quality was 11-81% [11]. The probable reason for the similarity of the findings might be both current and previous, population was the same which is a marginalized population.

However, the finding was higher than the study done in high-security women's prison in the US (72%) [12], the study done in China on the prevalence and risk factors of poor sleep quality among Chinese elderly in an urban community (10% and 48%) [14], the study done on prevalence and factors associated with poor sleep quality among secondary school teachers in a developing country (16 to 67%) [16] and study conducted among community in Ethiopia showed that the overall prevalence of poor sleep quality was 65.4% [3].

The first probable reason for the different prevalence rates might be due to the different study areas. Most of the previous studies were in developed countries [12, 14], in developed countries there might be a supply of better health services for prisoners. The second reason could be most of the previous study were done in the general community [3, 14, 16], but the current study was conducted on the prisoners. Prisoners sleep on the floor from lack of space [9]. In view of this, the prevalence of poor sleep quality is higher among prisoners than the general population.

On the other hand, this study finding was lower than the study done in England in adult prison populations showed prevalence poor sleep quality 88.2% [7]. The variation might be in the previous study, the participants were collected across three different prisons, two male prisons and one female prison [7] but the current study was conducted only on one prison. The other possible reason for difference might be in the previous study the data was collected for long duration of time, which is more than one year. while, in the current study, the data were collected within a month.

Regarding factors affecting poor sleep quality, the study finding revealed that marital status, educational status, history of previous incarceration, residence before incarceration and lifetime alcohol use had significant association with poor sleep quality.

The results of this study revealed that prisoners, those incarcerated previously, had poor sleep quality compared to those admitted for the first time in prison. This might be explained by the fact that prisoners develop poor sleep quality as a result of repeated exposure to the prison environment. In addition, prison is a place where high control and restriction of movement is common; absence of different services and recreational activities, not well designed or equipped to provide different requirement prisoners. Furthermore, the prison experience can be inherently stressful, which can contribute to poor sleep quality. For example, prisoners experience a complete upheaval from normal life, family and routine, forced contact with others and lack of autonomy [11]. Thinking about the past and looking back on life choices also contributed to poor sleep. For some prisoners, guilt and shame over criminal actions also contributed to poor sleep [12]. Occurrence of poor sleep quality is high in stressful environment.

Prisoners who came from urban residence were more likely to develop poorer quality of sleep compared to rural dwellers. The probable reason might be that urban residents go to bed later than rural residents. In addition, use of technology and social media is higher in urban dwellers than rural dwellers during night time; however, in the prison, such service are restricted which resulted in poor sleep quality in the current study. The results of this study showed that single, widowed and divorced prisoners were less likely to develop poor sleep quality when compared to married status. The probable reason might be married prisoners have different responsibility as they are responsible for their family.; as it's known, married individuals support their children, parents or other relatives and when imprisoned they might develop poorer sleep quality than single prisoner. On the other hand, when a married individual incarcerated, because of separation from partner, they are more prone for poor sleep quality.

This study revealed that there was statistically significant association between low educational status and poor sleep quality. This finding is supported by a study completed in South Korea on factors associated with poor sleep quality in primary care [2]. The possible reason might be living conditions in prison are worst and lack autonomy which leading to poor sleep quality. Those educated might be taking different measures to get better sleep quality, like involving work in prison. The other possible reason could be regularly performing physical exercise was a protective factor of poor sleep quality [14].

In the current study, lifetime alcohol use and poor sleep quality shown significant association. This finding agrees with a study done in England and Wales, insomnia management in prisons in a mixed-method study [11]. The reason might be explained by the fact that many people used alcohol for relaxation, followed by relieving stress. it's clear that, prison is stressful environments which make prisoners distressed and disturb their sleep pattern. As in prison, when they want alcohol to get enough sleep, they could not get as they need. This can be devastating to prisoners, thereby leading to deterioration in their psychological and social wellbeing making more prone to poor sleep quality.

In conclusion, poor sleep quality among prisoners was significantly high. Marital status, educational status, history of previous incarceration, residence before incarceration and lifetime alcohol use had significant association with poor sleep quality. Routine screening and availing management in the prison may be of great importance.

Based on the findings, recommendations are made to the administrators of prison:

Employ/hire mental health professionals to work in prison.

Provide training for prisoners on effect of substance use.

Formal education in prison, linking to the nearby educational institutions.

Follow condition of the prisoners by improving bedroom and better bedding.

Recommendations for University:

Availing routine screening and treatment options for poor sleep quality for the prisoners.

Launch workshops on type of stress management linked with the prison’s clinic.

Recommendations for Ministry of health

Provide coordinated mental health services in prison.

Recommendations for researcher:

As the first study, further studies are needed to assess poor sleep quality and associated factors among prisoners and its possible intervention.