Sleep quality, daytime sleepiness and fasting insulin levels in women with chronic obstructive pulmonary disease.

STUDY

OBJECTIVES

To test the clinical observations that patients with chronic obstructive pulmonary disease (COPD) have impaired sleep quality without excessive daytime sleepiness (EDS), and to analyse the aetiological factors.

PARTICIPANTS

Fifteen non-diabetic postmenopausal women with moderate to severe COPD and 20 community dwelling age-matched control women.

MEASUREMENTS AND

RESULTS

Patients completed questionnaires, had a polysomnography and blood tests. Controls filled in the questionnaires. In the Basic Nordic Sleep Questionnaire, the average (+/-sd) scores for sleepiness (9.9+/-3.0 in patients vs. 7.6+/-3.2 in controls, P = 0.025, test range 4-20) and insomnia (18.3+/-3.4 vs. 16.6+/-4.4, P = 123, test range 7-35) were low. Although 53% had a good night's sleep seldom or never and 70% slept restlessly, only 33% felt tired in the mornings. Controls reported better sleep quality, less tiredness and sleepiness. With polysomnography, the total sleep time was 4h 41 min +/-1h 20 min in patients. Sleep was fragmented, the proportion of stage 1 sleep high and rapid eye movement (REM) latency delayed. Sleepiness correlated with fasting serum insulin levels (r = 0.59, P = 0.027) and body movements (r = 0.52, P = 0.047). In stepwise linear regression analyses, sleepiness was positively associated with insulin levels (P = 0.025) but not with body movements. Insulin explained 38.0% of the variance in the sleepiness score, when adjusted for body mass index (BMI).

CONCLUSIONS

Despite short and fragmented sleep, non-diabetic patients with COPD did not have marked EDS. An association between fasting insulin and sleepiness suggests that insulin resistance is involved in EDS.