Human phase response curve to a 1 h pulse of bright white light

•  The human circadian pacemaker generates near‐24‐h rhythms that set the timing of many physiological, metabolic and behavioural body rhythms, and is synchronized to environmental time primarily by the 24 h light–dark cycle. •  The magnitude and direction of the resetting response of the pacemaker to light depends on the time of day of exposure, and the change in responses over the day is summarized in a phase response curve (PRC). •  A previous PRC showed that a 6.7 h bright white light exposure maximally shifted the circadian pacemaker by over 3 h. •  We show that a PRC to a 1 h bright white light pulse maximally shifted the circadian pacemaker by ∼2 h, despite representing only ∼15% of the exposure duration. •  This study demonstrates that the circadian pacemaker is sensitive to short‐duration light pulses with a non‐linear relationship between light duration and the amount of resetting.