Systems and methods to provide light therapy to a subject use a light source configured to emit pulses of electromagnetic radiation consisting substantially of blue light. By virtue of the emitted pulses of electromagnetic radiation within a particular range of wavelengths impinging on an eye or eyelid of the subject, the phase of the circadian rhythm of the subject is shifted. Such a shift may be accomplished in such a way that the level of melatonin production is not substantially suppressed.
