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 Table of Contents  
Year : 2018  |  Volume : 8  |  Issue : 1  |  Page : 36-40

Comparison of perceived sleep quality among urban and rural adult population by Bengali Pittsburgh Sleep Quality Index

1 Department of Physiology, MKCG Medical College, Ganjam, Odisha, India
2 Department of Physiology, Medical College and Hospital, Kolkata, West Bengal, India
3 JB Roy State Ayurvedic Medical College, Kolkata, West Bengal, India

Date of Web Publication5-Jan-2018

Correspondence Address:
Dr. Himel Mondal
Department of Physiology, MKCG Medical College, Ganjam, Odisha
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/AIHB.AIHB_44_17

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Background: Pittsburgh Sleep Quality Index (PSQI) assesses perceived quality of sleep. Bengali is the 6th language in the world according to the number of first language speakers. PSQI is presently not available in Bengali. Poor quality of sleep affects work efficiency and health of individual and it is increasing in urban as well as in rural population. Aim: The aim of the study was (1) to adapt PSQI in Bengali Language and (2) to find the prevalence rate of poor quality of sleep among urban and rural populations and to compare the rate. Materials and Methods: First, Bengali PSQI (BPSQI) was adapted by linguistic validation methods. Then, a cross-sectional survey was conducted among sample in a municipal ward and in a village by BPSQI. The prevalence of poor sleep quality among the sample was ascertained. Data were presented in percentage, mean and standard deviation. Chi-square test and unpaired t-test were used according to necessity with α = 0.05. Results: Adapted BPSQI instrument was found of acceptable internal consistency (Cronbach's α = 0.816). The prevalence rate of poor sleep quality in urban adult population was 42.58% and rural population was 35.89% (χ2 = 4.004, P = 0.0454). Adult females in urban area showed more prevalence rate of poor sleep quality (58.74%) than those of adult females in rural area (45.96%). Conclusion: Adapted BPSQI can be used as a self-administered questionnaire among Bengali native speakers. A significant percentage of urban and rural adult population suffers from poor quality of sleep. Adult population in urban area, especially adult females, suffers more from poor quality of sleep than rural population.

Keywords: Bengali language, insomnia, linguistic validation, subjective sleep quality, urbanisation

How to cite this article:
Mondal H, Mondal S, Baidya C. Comparison of perceived sleep quality among urban and rural adult population by Bengali Pittsburgh Sleep Quality Index. Adv Hum Biol 2018;8:36-40

How to cite this URL:
Mondal H, Mondal S, Baidya C. Comparison of perceived sleep quality among urban and rural adult population by Bengali Pittsburgh Sleep Quality Index. Adv Hum Biol [serial online] 2018 [cited 2023 Mar 27];8:36-40. Available from: https://www.aihbonline.com/text.asp?2018/8/1/36/222245

  Introduction Top

Pittsburgh Sleep Quality Index (PSQI) is an instrument developed by Buysse et al. in 1989 to assess the quality of sleep in previous 1-month period.[1] This instrument is copyrighted by the University of Pittsburgh. However, it can be reprinted for educational and in non-commercial research.[2] This instrument, originally available in English, has been translated into 56 languages.[3]

According to the number of first language speakers, Bengali is the 6th language in the world.[4] It is the national language of Bangladesh. It is among the 23 official languages of India, with 8.11% population with Bengali as their mother tongue which stands second in descending order of speaker's strength (2001).[5] Maximum native speakers live in West Bengal, Tripura, Assam and Andaman and Nicobar Islands.[6] PSQI is available in Indian languages such as Hindi and Marathi.[7] However, it is currently not available in Bengali language.

It is well documented that urbanisation increases stress level and affects sleep quality.[8] In addition, a study by Ravikiran et al. found that a significant percentage of rural children also suffer from sleep problems.[9] A study by Tang et al. showed that more than one–fourth of populations suffers from insomnia in China and there was significantly more prevalence in rural population than urban population.[10] To the best of our knowledge, no study has been carried out to compare subjective sleep quality among urban and rural adult population in the North 24 Parganas District, West Bengal, India.

With this background, the aim of this study was to first adapt Bengali version of PSQI (BPSQI) through extensive language validation methods and to compare perceived sleep quality among urban and rural populations.

  Materials and Methods Top

This study was a survey-based study. All the experts and participants for the study were taken from adult age group (i.e., age >18 years). The study was conducted according to guidelines by ‘WMA declaration of Helsinki’ after obtaining informed written consent from the experts and participants. The study was divided into two phases. The first Phase was forward translation and back translation and drafting of the final scale which was carried out during the period of October 2016 to December 2016. The second phase was assessment of sleep quality among population in an urban area and in a rural area situated in North 24 Parganas district. The second phase of the study was carried out during January 2017 to April 2017.

Linguistic validation of Bengali version of Pittsburgh Sleep Quality Index

The original version of PSQI was developed in English. The scale has ten items.[1] Among the items, the tenth item records responses of roommate or bed partner. This item is not considered for global PSQI scoring.[2],[11] Hence, we omitted the 10th item from the scale. Several previous studies were conducted with 9-item PSQI scale.[12],[13],[14] As the scale was used without the 10th item of original PSQI instrument available in Pittsburgh website,[2] the PSQI used in this study also be called as ‘modified PSQI’ and Bengali version may also be called ‘modified BPSQI’.

Linguistic validation was carried out according to guidelines by the WHO with some additional measures.[15] A project coordinator was appointed by the authors who was Bengali, bilingual and had a master's degree in English. The aim and objectives of the study was discussed in detail with the coordinator. Special discussion for expert panel selection was emphasised. Expert panel for forward translation from English to Bengali comprised of four personnel (a psychologist with interviewing expertise, an English teacher with Master's/Doctoral degree with expertise in translation, a Bengali teacher with Master's/Doctoral degree with expertise in translation and a physiologist with experience in questionnaire development). Mother tongue of those experts was Bengali.

Printed English version of modified PSQI was distributed among the experts via the coordinator. All of them translated the questionnaire from English to Bengali with emphasis on conceptual translation rather than linguistic translation. After receiving the translated questionnaires, a meeting was conducted by the coordinator. After discussion among the experts and coordinator, necessary addition, deletion and modification were done in the questionnaire and a final version was drafted by the coordinator. This questionnaire was received from the coordinator. It was reviewed by the authors and preserved.

Similar but another set of experts were selected by the project coordinator. However, the medium of study of this group was English during their schooling. They were given the newly translated Bengali version questionnaire via the coordinator to translate it into English. After translation of questionnaire from Bengali to English by individual expert, a meeting was conducted among the experts. After discussion among them, a final draft of English-modified PSQI was obtained by the coordinator. This version was compared with the original instrument. The content was found to be equivalent to the original instrument, though there was difference in words and phrases. Hence, no further forward or back translation was carried out and the BPSQI was accepted as the final version of the questionnaire. The whole procedure of translation is depicted in [Figure 1].
Figure 1: Flow chart depicting procedure of adaptation of English version of Pittsburgh Sleep Quality Index in Bengali language.

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Pilot survey and cognitive interview

Literature about subjective sleep quality among urban and rural populations was not available for the targeted state of study, as well as for India. Hence, a pilot study was carried out to ascertain prevalence rate. This pilot study was also used as cognitive interview for the newly adapted instrument. List of adult population was obtained from the voter list of ward no. 8 in Barasat municipality area (i.e., urban area) and Panchita village in Dharampukuria Gram Panchayat (i.e., rural area). Available voter list (updated 1st January 2017) was printed from the Election commission website for convenience.[16] A systemic random sample (n = 30) from each area was selected. Survey in urban area was conducted by the second author and rural area by the third author. After obtaining written informed consent, the BPSQI was given to participants to fill up. The participants filled the self-administered questionnaire in front of the author. Among the sample, three participants were illiterate in rural area and for them data were collected by an interview. After getting filled-up questionnaire in case of literate individuals, participants were asked questions about their understanding and difficulty in understanding about the questionnaire. These questions were pre-planned to gather information about participant's perception about the questionnaire, to point out difficult word or phrase and to find any cultural issue. The filled-up questionnaires were coded and scored. From the pilot study, prevalence of poor sleep quality was found to be 37.8% in urban population and 28.2% in rural population. According to the experience of the pilot study, two phrases were changed after discussion among authors. Thus, a final draft of BPSQI was obtained.

Sampling technique

With a prevalence rate of 37.8% in urban population and 28.2% in rural population, the sample size was calculated according to the following formula:[17]

n = (Z/α//2 + Z/β)2* (p/1 [1 − p/1] + p/2 [1 − p/2])/(p/1 − p/2)2

The confidence level was set at 95% and power of the study was set at 80%. Calculated minimum sample size was 373 in each group. With assumption of unavailability of some participants during the survey period and unwillingness in participation, the sample size was multiplied with 1.25. Hence, the final sample size was calculated as 466 for each group. Those participants who were surveyed in pilot study were marked and excluded from the voter list. Systemic random sampling was used to select and mark the participant on the available voter list. This marked voter list was used during the survey for easy identification of the targeted sample.

Survey proper

The survey was conducted during the month of January through April, 2017. The survey in rural area was conducted partly by the third author and partly by two experienced surveyors. In urban area, the whole survey was conducted by three experienced surveyors. Participants were briefed about the aim of the survey, and written informed consent was taken. Demographic details were recorded in one form by interviewing the participant. For literate person, and willingness to fill up, the BPSQI was self-administered, and for illiterate person, the BPSQI was self-reported with the help of interviewer. During the survey period, last 10 days were allotted for mop-up round to get the response from those who were previously absent during survey. Data obtained were scored and coded in spread sheet and stored for analysis.

Statistical analysis

Statistical analysis was carried out in Microsoft Excel® 2010. Seven components of PSQI scoring were taken for internal consistency test after pilot study by Cronbach's α. It was calculated in Microsoft Excel® manually according to formula by Machin et al.[18] Mean and standard deviation was computed for score of the seven components (viz., subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction). Mean of the two groups was compared by unpaired t-test with α = 0.05. Global score of each group was also expressed in mean and standard deviation and compared by unpaired t-test with similar chances of type I error. Global score >5 was considered as an indicator of poor sleep quality. Prevalence rate of poor sleep quality was calculated for both groups and tested statistically by Chi-square test with α = 0.05.

  Results Top

The reliability of newly adapted instrument (i.e., BPSQI), tested by Cronbach's alpha (α =0.816), was in the acceptable range (i.e., 0.7–0.95).[19]

In urban area, the survey was completed on 411 (88.20% of targeted sample) participants (male = 188 [45.74%], female = 223 [54.26%]). Among the participants, in urban area, 344 (83.70%) filled the questionnaire themselves (i.e., self-administered) and 67 (16.30%) were self-reported with the help of interviewer. The mean age of respondents in urban area was 38.56 ± 13.88 years. Age-, sex- and marital status-wise distribution of participants in urban area according to BPSQI global score is shown in [Table 1]. The prevalence of poor quality sleep (i.e., Global score >5) among urban population was 42.58%.
Table 1: Age-, sex- and marital status-wise distribution of participants in urban area (n=411) and their Bengali Pittsburgh Sleep Quality Index global score

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In rural area, survey was completed on 443 (95.06% of targeted sample) participants (male = 208 [46.95%], female = 235 [53.05%]). In rural area, 252 (56.88%) filled the questionnaire themselves and 191 (43.12%) were self-reported with the help of interviewer. The mean age of respondents in the rural area was 37.98 ± 13.14 years. Age-, sex- and marital status-wise distribution of participants in rural area according to BPSQI global score is shown in [Table 2]. The prevalence of poor quality sleep in rural population was 35.89%.
Table 2: Age-, sex- and marital status-wise distribution of participants in rural area (n=443) and their Bengali Pittsburgh Sleep Quality Index global score

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Comparison of prevalence of poor sleep quality among respondents in urban population and rural population is shown in [Table 3].
Table 3: Comparison of sleep quality among respondents of urban and rural areas

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The mean score for the seven components of BPSQI and global score among urban and rural populations are shown in [Table 4].
Table 4: Bengali Pittsburgh Sleep Quality Index scores for individual components expressed in mean±standard deviation among respondents of urban and rural areas

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  Discussion Top

The outcome of this study is a language-validated BPSQI survey instrument with an accepted level of internal consistency. Majority of the participants (69.78%) filled up the questionnaire themselves. This instrument can be used in further studies to assess sleep quality in population whose native language is Bengali. This would help psychiatrists, psychologists or clinicians who would like to check patient's perceived sleep quality. The soft copy of BPSQI can be obtained via E-mail from the corresponding author. However, the limitations of the original instrument are also present in this version also. The questionnaire can only measure the sleep quality for previous 1-month duration only. In addition, it is the perceived sleep quality of the individual, which may not be corroborative with actual sleep quality.

Prevalence of poor sleep quality found in urban population (42.58%) from this study was more than the prevalence of insomnia (15.4%) found by Roy et al. in an urban area in the same district.[20] The survey instrument used by the author was different from that of the instrument used in this study. However, this finding points towards the fact that there are diverse causes for poor quality of sleep and insomnia is one of them.[21] From the current study, it was ascertained that the prevalence rate of poor sleep quality was more in urban population [Table 3]. This result is not concordant with the finding by Tang et al.,[10] who found an increased prevalence rate of poor sleep quality among rural Chinese population. Probable reason behind this discrepancy may be cultural difference between the populations of these countries.

Adult male population has almost similar level of poor sleep quality (23.4%) as that of rural adult males (24.52%). However, adult female participants in urban area have a higher prevalence of poor sleep quality (58.74%) than that of rural adult females (45.96%). The prevalence rate of poor sleep quality is found to be higher in old age. Presence of geriatric diseases may be the contributing factors for this finding which was beyond the scope of this study.

From individual score of BPSQI, it was evident that there is a significant difference in sleep duration among rural and urban populations [Table 4]. Rural population showed less sleep duration. The reason behind it may be the lifestyle difference among rural and urban populations. Despite this finding, use of sleep medication was more common in urban population. Easy availability of healthcare facility, level of awareness and more stress in urban life may be contributing factors.


This study has some limitations. Only perceived sleep quality was tested, sleep quality was not tested by polysomnograph. Samples from a single municipal ward and from a single village in rural area were surveyed. Further study with larger sample size would reflect more generalised result.

  Conclusion Top

PSQI was adapted in Bengali language with extensive linguistic validation. Internal consistency of the instrument was satisfactory. The newly adapted instrument is feasible to administer in Bengali native speakers in urban and rural populations. Urban population has more prevalence rate of poor sleep quality than that of rural population. Adult females, in both urban and rural areas, suffer more from poor quality sleep than adult males.


We thank the coordinator Sarika Mondal, M. A. (English) and expert panel members for their immense help during the translation of the instrument. We are thankful to Dr. Rajesh De, Department of Community Medicine, R. G. Kar Medical College, Kolkata, West Bengal, for his help during initial design of the study. We acknowledge the help of the surveyors who conducted the survey.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]

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