Human phase response curve to a single 6.5 h pulse of short‐wavelength light

•  The human ∼24 h circadian pacemaker ensures appropriate timing of physiological, behavioural and metabolic events and is synchronized to the 24 h day primarily by the 24 h light–dark cycle. •  The direction and magnitude of photic resetting depend on the timing of light exposure, and are described by a phase response curve (PRC). •  The human circadian photoreception system is functionally and anatomically distinct from the visual system and employs a novel photoreceptor, melanopsin, which is maximally sensitive to short‐wavelength (blue) visible light. •  We constructed a PRC to 6.5 h of blue (480 nm) light and compared it with a prior 6.7 h white light PRC; the blue light PRC achieved ∼75% of the resetting response of the white light PRC. •  This study suggests that short‐wavelength visible light exposures may be more efficient than traditional high‐intensity white light exposures for treatment of circadian rhythm sleep disorders.