Table 1. Epidemiological studies of sleep disturbance and night-time symptoms in chronic obstructive pulmonary disease (COPD)
CitationPopulation/methodRelevant 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 difficultiesSymptom 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 yrsBreathing 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 dayNight-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.