Figure 2

Importance of timing treatment: Phase shift (ΔΦ) of peak expiratory flow (PEF) rhythm as a function of timing of prolonged corticosteroid therapy in children with severe asthma. Drastic differences in direction and extent of drug-induced shift of a circadian acrophase as a function of medication timing. The reference phase (0°) is the phase of PEF of a group of untreated children with asthma in remission. Vertical 95% confidence intervals indicate detection of statistically significant circadian rhythm (by cosinor) [15].