Figure 1.

Circadian variation of COPD symptoms: *p<0.001 versus “midday”, “afternoon”, “evening”, “night” and “difficult to say” groups; p=0.006 versus “no particular time of day” (all COPD patients); ^†p<0.001 versus “midday”. Patient insight into the impact of chronic obstructive pulmonary disease in the morning: an internet survey. Partridge MR, Karlsson N, Small IR, et al. Curr Med Res Opin. 2009;25:2043–2048. Informa UK Ltd, trading as Taylor & Francis Group, reprinted by permission of the publisher (Taylor & Francis Ltd, http://www.tandfonline.com).⁴