Sleep-onset time variability and sleep characteristics on weekday and weekend nights in patients with COPD

OBJECTIVE: To evaluate sleep-onset time variability, as well as sleep characteristics on weekday and weekend nights, in individuals with moderate-to-severe COPD. METHODS: Sleep was objectively assessed by an activity/sleep monitor for seven consecutive nights in individuals with COPD. For analysis, individuals were divided into two groups according to sleep-onset time variability results, characterized by intrasubject standard deviation of sleep-onset time (SOT(V)) ≥ 60 min or < 60 min. RESULTS: The sample comprised 55 individuals (28 males; mean age = 66 ± 8 years; and median FEV(1) % of predicted = 55 [38-62]). When compared with the SOT(V)<60min group (n = 24), the SOT(V)≥60min group (n = 31) presented shorter total sleep time (5.1 ± 1.3 h vs. 6.0 ± 1.3 h; p = 0.006), lower sleep efficiency (73 ± 12% vs. 65 ± 13%; p = 0.030), longer wake time after sleep onset (155 ± 66 min vs. 115 ± 52 min; p = 0.023), longer duration of wake bouts (19 [16-28] min vs. 16 [13-22] min; p = 0.025), and higher number of steps at night (143 [104-213] vs. 80 [59-135]; p = 0.002). In general, sleep characteristics were poor regardless of the day of the week, the only significant difference being that the participants woke up about 30 min later on weekends than on weekdays (p = 0.013). CONCLUSIONS: Sleep-onset time varied over 1 h in a standard week in the majority of individuals with COPD in this sample, and a more irregular sleep onset indicated poor sleep quality both on weekdays and weekends. Sleep hygiene guidance could benefit these individuals if it is integrated with their health care.