Previous studies have reported time of day variation in both established and emerging cardiovascular disease (CVD) risk factors in middle-aged adults, such as blood pressure, lipids and some well-established inflammatory and haemostatic factors (eg, white cell, red blood cell and platelet counts).1–3 However, the extent to which some emerging CVD risk factors such as interleukin (IL)-6, a marker of inflammation causally associated with CHD in a recent study,4 and N-terminal pro-brain natriuretic peptide (NT-proBNP), a marker of heart failure,5 vary by time of day have been less studied. The gene discussed is NPPB; the disease is heart failure.