| Citation | Population/method | Relevant results |
| Klink and Quan [22] (1987) | Prospective epidemiological study of 2187 adults A diagnosis of “obstructive airways disease” identified by questionnaire in 301 individuals Sleep questionnaire (six items) used to evaluate sleep problems | Age-dependent effects on DIMS, EDS and nightmares DIMS prevalence ranged from 29–45% depending on age, sex and condition Significant relationship between DMIS and EDS and the presence of chronic bronchitis, concomitant asthma and emphysema |
| Klink et al. [23] (1994) | As for Klink and Quan [22], 1987 Questionnaire and spirometry used to identify patients with respiratory symptoms 443 individuals had one respiratory symptom 299 individuals had two respiratory symptoms | Presence of DIMS and EDS were predicted by wheezing and sputum but not spirometry Insomnia was reported in 39–53% depending on symptoms EDS was reported in 12–23% of those with respiratory symptoms |
| Lewis et al. [24] (2009) | Oximetry in 803 subjects from an outpatient COPD service; overnight oximetry in 59 patients who had resting oxygen saturation <95% Questionnaires: CRQ, SF-36, PSQI, ESS and FOSQ | Focus on hypoxaemic component Frequency of nocturnal desaturation (30% of the time <90%) estimated to be 4.8% Desaturation was not associated with impaired HRQoL, sleep quality or daytime function |
| Cormick et al. [25] (1986) | Case–control study among 50 COPD patients and 40 age- matched controls Sleep study in a subset of 16 patients with COPD | Problems with DIMS (18–76%) and EDS (72%) over-represented in patients Hypnotics used by 28% of patients versus 10% of controls In a subgroup of 16 patients, sleep architecture disturbed in most patients: 12 out of 16 had hypoxaemia (>40% time at <90% saturation) during sleep with arousals occurring 3–46 times per hour (mean 15 times per hour) |
| Valipour et al. [26] (2011) | Case–control study among 52 patients with mild–moderate COPD and 52 matched controls Sleep disorders questionnaire and polysomnography | Sleep efficiency, total sleep time and mean saturation lower among COPD patients versus controls 36% of COPD patients had problems falling asleep and 76% experienced frequent awakenings Minimum oxygen independently predicted symptom scale scores |
| Kinsman et al. [27] (1983) | 146 patients with chronic bronchitis and emphysema were asked to rate the frequency with which 89 symptoms and experiences occurred during their breathing difficulties | Symptom category “sleep difficulties” rated as third after dyspnoea and fatigue |
| Karachaliou et al. [28] (2007) | Multicentre questionnaire and spirometry study including physician-diagnosed asthma and COPD in 10 primary care centres n = 1501, aged 19–90 yrs | Breathing pauses in 11% and EDS in 6.7% Breathing pauses: OR 1.45 (95% CI 1.01–2.10) COPD versus asthma EDS: OR 2.04 (95% CI 1.33–3.14) COPD versus asthma |
| Tsai et al. [29] (2007) | Multicentre cohort study examining treatment and outcome in 582 patients presenting with COPD exacerbation to the emergency room during the night or during the day | Night-time patients (15%) had shorter duration of symptom exacerbation and were more likely to require noninvasive positive pressure ventilation COPD characteristics did not differ between groups |
DIMS: disorders of initiating and maintaining sleep; EDS: excessive daytime sleepiness; CRQ: Chronic Respiratory Questionnaire; SF-36: Short Form-36 questionnaire; PSQI: Pittsburgh Sleep Quality Index; ESS: Epworth Sleepiness Scale; FOSQ: Functional Outcomes of Sleep Questionnaire; HRQoL: health-related quality of life.