We studied patients who died in this hospital from chronic bronchitis and emphysema during 1977-8X, excluding those with coexisting lung cancer. There were 54 such patients (42 men, 12 women), whose mean (SD) age was 71 (8-7) years. We also examined two control groups matched for age and sex, consisting of 54 patients who died from non-respiratory neoplasms and 54 who died from cerebrovascular disease. For analysis the day was divided into three periods of eight hours each: 11 pm to 7 am (night), 7 am to 3 pm (day), and 3 pm to 11 pm (evening). In this hospital patients are settled down to bed between 10 30 and 11 pm and woken up around 7 am. Thus the night period approximated to the expected period of sleep.

The table shows that there was no significant difference in the pattern of mortality over time between the two control groups, whereas most of the patients with chronic bronchitis and emphysema died at night (p< 0 05, x2 test). The highest mortality in these patients was in the first hour of the