Figure 7

Chronobiologic serial section. Peak expiratory flow was self-measured several times a day by a 53-year old man. The data covering a 14-month span are shown in row 1. They are analyzed in a 20-day interval progressively displaced by 2 days. Data in each interval are fitted with a 24-hour cosine curve. From the P-values shown in row 2, it can be seen that the circadian rhythm was detected with statistical significance most of the time, except for two short spans, one coinciding with a transmeridian flight (when fewer data were collected, row 5) and the other with influenza. Whereas the 24-hour acrophase remains relatively stable throughout the record (row 4), the MESOR (row 3, lower curve) and to a lesser extent the circadian amplitude (row 3, distance between the two curves) undergo sharp changes, notably in association with the influenza and earlier with a change in treatment timing. © Halberg Chronobiology Center.