European Journal of Cardiovascular Medicine

Chronic respiratory diseases represent a major clinical burden because they produce persistent symptoms, functional limitation, recurrent exacerbations, and impaired health-related quality of life[1]. Conditions such as chronic obstructive pulmonary disease (COPD), bronchial asthma, interstitial lung disease, bronchiectasis, and post-tuberculosis sequelae frequently present with cough, dyspnea, wheeze, sputum production, and reduced exercise tolerance[2,3]. These symptoms are not limited to daytime activity. In many patients, respiratory discomfort continues during the night, disturbing sleep onset, sleep maintenance, and the restorative value of sleep. Sleep disturbance is therefore an important but frequently under-recognized clinical dimension in respiratory medicine [4,5].

Sleep and breathing are physiologically linked. During sleep, especially during rapid eye movement sleep, ventilation becomes more dependent on diaphragmatic activity, upper airway tone decreases, and arousal responses change. Patients with chronic respiratory diseases are vulnerable to nocturnal hypoventilation, oxygen desaturation, cough-related awakenings, bronchospasm, and sleep fragmentation. These disturbances can worsen fatigue, mood, cognition, adherence to therapy, and daytime functioning. In COPD, disturbed sleep has been associated with worse health status, poorer quality of life, dyspnea burden, and more severe disease [6]. Similar concerns have been reported in asthma, where poor sleep quality is linked with poor asthma control and reduced quality of life [5].

Assessment of sleep complaints in respiratory clinics is usually simple, inexpensive, and clinically informative. The Pittsburgh Sleep Quality Index (PSQI) is a validated self-rated instrument that evaluates sleep quality and sleep disturbances during the preceding month, with higher scores indicating poorer sleep quality. The Epworth Sleepiness Scale (ESS) is widely used to quantify subjective daytime sleep propensity in common daily situations. These tools are useful in observational studies because they capture patient-centered outcomes that are often missed during routine spirometric or symptom-based evaluation.

Previous studies have demonstrated that poor sleep quality is common in COPD, asthma, bronchiectasis, and interstitial lung disease, but the magnitude and associated clinical factors vary across populations [6,7]. Indian hospital-based data remain useful because respiratory disease patterns, smoking practices, socioeconomic factors, health-seeking behavior, and post-infective lung damage differ from Western cohorts. Identifying sleep impairment in such patients can help clinicians broaden management beyond airflow limitation and acute symptom control.

The present study was conducted to evaluate sleep quality and daytime sleepiness among patients with chronic respiratory diseases. The objectives were to estimate the frequency of poor sleep quality and excessive daytime sleepiness, describe nocturnal respiratory symptoms, and assess their association with respiratory disease type, disease severity, dyspnea grade, exacerbation history, and resting oxygen saturation.

Study design and setting:

This hospital-based cross-sectional observational study was conducted in the Department of Pulmonary Medicine at Kamineni Institute of Medical Sciences (KIMS), Narketpally, Telangana, India. The study period extended from August 2016 to January 2017. The study was designed to evaluate subjective sleep quality and daytime sleepiness among patients with chronic respiratory diseases using standardized questionnaire-based assessment.

Study population:

A total of 100 adult patients diagnosed with chronic respiratory diseases were included by consecutive sampling from outpatient and inpatient respiratory services. Eligible patients included those with COPD, bronchial asthma, interstitial lung disease, bronchiectasis, or post-tuberculosis sequelae. Patients aged 18 years and above who were clinically stable and able to understand the questionnaire were included. Patients with acute respiratory failure, recent critical illness, altered sensorium, known psychiatric illness interfering with questionnaire response, current sedative drug abuse, or unwillingness to participate were excluded.

Data collection and clinical assessment:

Demographic details such as age and gender were recorded. Smoking status was categorized as non-smoker, former smoker, or current smoker. The primary respiratory diagnosis was documented based on clinical history, examination, radiological findings, spirometry where applicable, and treating physician diagnosis. Disease severity was classified as mild, moderate, or severe using available clinical and functional information. Nocturnal symptoms including cough, breathlessness, wheeze, snoring, frequent awakening, and early morning fatigue were recorded. Dyspnea was assessed using the modified Medical Research Council grading system. Exacerbation history during the preceding year and resting peripheral oxygen saturation were also documented because these variables are clinically linked with sleep disruption in chronic respiratory disease [4,8-10].

Assessment of sleep quality and daytime sleepiness: Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), a self-rated instrument that evaluates sleep over the previous one month [1]. A global PSQI score greater than 5 was considered poor sleep quality. Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS), which measures the chance of dozing in common daily situations [2,3]. ESS scores from 0 to 10 were considered normal, 11 to 12 as mild daytime sleepiness, 13 to 15 as moderate daytime sleepiness, and scores above 15 as severe daytime sleepiness.

Statistical analysis:

Data were entered into a spreadsheet and analyzed using descriptive and inferential statistics. Continuous variables were expressed as mean ± standard deviation, while categorical variables were expressed as frequency and percentage. The association of respiratory disease type and disease severity with poor sleep quality and excessive daytime sleepiness was assessed using the chi-square test or Fisher exact test as appropriate. Correlation between sleep scores and clinical parameters was assessed using correlation coefficients. A p value less than 0.05 was considered statistically significant.

Ethical considerations:

The study was conducted after obtaining institutional permission. Written informed consent was obtained from all participants. Patient confidentiality was maintained throughout data collection and analysis. The study did not involve any experimental intervention, and questionnaire assessment did not alter the routine clinical care provided to the participants.

A total of 100 patients with chronic respiratory diseases were included in the study. The mean age of the study population was 56.8 ± 13.2 years. Most patients were in the 51-60 years age group. Males constituted 62% of the study population. Chronic obstructive pulmonary disease was the most common respiratory illness, followed by bronchial asthma. Moderate disease severity was observed in nearly half of the patients (Table 1).

Table 1. Baseline demographic and clinical profile of patients with chronic respiratory diseases

Sleep quality was assessed using the Pittsburgh Sleep Quality Index. The mean PSQI score was 8.6 ± 3.2. Poor sleep quality, defined as PSQI score greater than 5, was observed in 68% of patients. Daytime sleepiness was assessed using the Epworth Sleepiness Scale. The mean ESS score was 9.4 ± 4.1. Excessive daytime sleepiness, defined as ESS score greater than 10, was present in 39% of patients (Table 2).

Table 2. Distribution of sleep quality and daytime sleepiness among the study population

Poor sleep quality was most common among patients with COPD and interstitial lung disease. However, the association between type of respiratory disease and sleep quality was not statistically significant. Disease severity showed a significant association with both poor sleep quality and excessive daytime sleepiness. Patients with severe disease had the highest frequency of impaired sleep quality and daytime sleepiness (Table 3).

Table 3. Association of respiratory disease type and disease severity with sleep quality and daytime sleepiness

Nocturnal symptoms were frequently reported by patients with chronic respiratory diseases. Frequent awakening was the most common sleep-related complaint, followed by nocturnal cough, early morning fatigue, nocturnal breathlessness, and wheeze. A significant positive correlation was observed between PSQI and ESS scores, indicating that patients with poor sleep quality had higher daytime sleepiness. PSQI and ESS scores also showed significant correlation with disease duration, dyspnea grade, exacerbation frequency, and resting oxygen saturation (Table 4).

Table 4. Nocturnal symptoms and correlation of sleep scores with clinical parameters

Overall, poor sleep quality was observed in more than two-thirds of patients with chronic respiratory diseases, while excessive daytime sleepiness was present in more than one-third. Higher disease severity, greater dyspnea burden, frequent exacerbations, nocturnal symptoms, and lower oxygen saturation were associated with impaired sleep quality and increased daytime sleepiness.

This study evaluated sleep quality and daytime sleepiness among 100 patients with chronic respiratory diseases. The findings show that sleep impairment was frequent, with 68% of patients having poor sleep quality and 39% having excessive daytime sleepiness. These observations support the concept that chronic respiratory diseases affect not only pulmonary mechanics and daytime symptoms but also nocturnal rest and next-day functioning. The mean PSQI score of 8.6 ± 3.2 indicates a clinically relevant burden of poor sleep in this hospital-based respiratory cohort.

The predominance of COPD and bronchial asthma in the present study is consistent with the common clinical distribution of chronic respiratory diseases in pulmonary practice. Poor sleep quality was more frequent among patients with COPD, interstitial lung disease, and bronchiectasis than among those with asthma or post-tuberculosis sequelae. Although the association between disease type and poor sleep quality was not statistically significant, the direction of the findings is clinically meaningful. Previous work has shown that COPD patients often experience fragmented sleep, nocturnal oxygen desaturation, poor health status, and impaired quality of life [6-10]. Studies in asthma have also reported that poor sleep quality is associated with worse asthma control and poorer quality of life [11,12].

Disease severity had a clear relationship with both sleep quality and daytime sleepiness in the present study. Poor sleep quality increased from 36.4% in mild disease to 86.7% in severe disease, while excessive daytime sleepiness increased from 18.2% to 60.0%. This graded pattern suggests that increasing respiratory burden contributes to disturbed sleep. Similar associations have been reported in COPD, where severe disease, worse dyspnea, poorer health status, and nocturnal hypoxemia are linked with worse sleep quality [8-10]. In interstitial lung disease, poor sleep quality has also been associated with sleepiness and symptom burden [14].

Nocturnal symptoms were common in this cohort. Frequent awakening, nocturnal cough, breathlessness, wheeze, snoring, and early morning fatigue are clinically important because they indicate overnight respiratory instability. Bronchiectasis studies have shown that sleep disturbance and night symptoms are associated with poorer health-related quality of life and disease severity [13]. In the present study, PSQI and ESS scores correlated positively with dyspnea grade and exacerbation frequency, and negatively with resting oxygen saturation. These findings suggest that sleep impairment is closely linked to disease activity, symptom intensity, and physiological compromise.

The significant correlation between PSQI and ESS scores indicates that poor nocturnal sleep translated into greater daytime sleepiness. This relationship is expected because fragmented sleep, reduced sleep duration, and nocturnal respiratory discomfort impair daytime alertness. The findings emphasize the value of adding simple sleep screening tools to routine respiratory assessment. PSQI and ESS are inexpensive, patient-centered instruments that provide clinically useful information beyond standard respiratory evaluation [1-3]. Early recognition of sleep impairment can guide counseling, optimization of respiratory treatment, evaluation for sleep-disordered breathing where indicated, and improved holistic care.

Limitations

This study was conducted at a single tertiary care center with a sample size of 100 patients. Sleep quality and daytime sleepiness were assessed using subjective questionnaires rather than polysomnography or actigraphy. Disease severity was categorized using available clinical information, and subgroup sizes for some respiratory diagnoses were small, limiting disease-specific comparison.

Poor sleep quality was common among patients with chronic respiratory diseases, affecting more than two-thirds of the study population. Excessive daytime sleepiness was present in more than one-third of patients. Sleep impairment was more frequent in patients with severe respiratory disease, greater dyspnea burden, frequent exacerbations, nocturnal symptoms, and lower resting oxygen saturation. A significant positive correlation between PSQI and ESS scores showed that poor nocturnal sleep was linked with daytime functional impairment. Routine assessment of sleep quality and daytime sleepiness should be incorporated into respiratory care to improve symptom recognition, treatment planning, and patient-centered outcomes in chronic respiratory disease.

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