A sleep mask configured to provide light therapy to a subject, the sleep mask comprising: an opaque shield for shielding the eyes of the subject from ambient radiation configured to cover the eyes of a subject wearing the sleep mask such that the shield provides a barrier between ambient radiation and the eyes of the subject; a first set of one or more radiation sources carried by the shield, the first set of radiation sources being configured to emit radiation in a first wavelength band onto the eyelid of the subject if the subject is wearing the sleep mask, wherein the first wavelength band includes wavelengths of electromagnetic radiation that impact the sleep cycle of the subject; a second set of one or more radiation sources carried by the shield, the second set of radiation sources being configured to emit radiation in a second wavelength band onto the eyelid of the subject if the subject is wearing the sleep mask, wherein the second wavelength band includes wavelengths of electromagnetic radiation that precondition the non-visual system of the subject for reception of electromagnetic radiation in the first wavelength band; and a controller configured (i) to control emission of radiation by the first set of radiation sources such that the first set of radiation sources emits radiation in pulses, and (ii) to control emission of radiation by the second set of radiation sources such that the second set of radiation sources emits radiation between the pulses of radiation emitted by the first set of radiation sources that preconditions the non-visual system of the subject for reception of electromagnetic radiation in the first wavelength band during the pulses of radiation emitted by the first set of radiation sources, characterized in that a duration of pulses of electromagnetic radiation in the first wavelength band is between 5 milliseconds and about 20 minutes and a duration of rest periods of electromagnetic radiation in the second wavelength band is between about 30 seconds and about 90 minutes. an opaque shield for shielding the eyes of the subject from ambient radiation configured to cover the eyes of a subject wearing the sleep mask such that the shield provides a barrier between ambient radiation and the eyes of the subject; a first set of one or more radiation sources carried by the shield, the first set of radiation sources being configured to emit radiation in a first wavelength band onto the eyelid of the subject if the subject is wearing the sleep mask, wherein the first wavelength band includes wavelengths of electromagnetic radiation that impact the sleep cycle of the subject; a second set of one or more radiation sources carried by the shield, the second set of radiation sources being configured to emit radiation in a second wavelength band onto the eyelid of the subject if the subject is wearing the sleep mask, wherein the second wavelength band includes wavelengths of electromagnetic radiation that precondition the non-visual system of the subject for reception of electromagnetic radiation in the first wavelength band; and a controller configured (i) to control emission of radiation by the first set of radiation sources such that the first set of radiation sources emits radiation in pulses, and (ii) to control emission of radiation by the second set of radiation sources such that the second set of radiation sources emits radiation between the pulses of radiation emitted by the first set of radiation sources that preconditions the non-visual system of the subject for reception of electromagnetic radiation in the first wavelength band during the pulses of radiation emitted by the first set of radiation sources, characterized in that a duration of pulses of electromagnetic radiation in the first wavelength band is between 5 milliseconds and about 20 minutes and a duration of rest periods of electromagnetic radiation in the second wavelength band is between about 30 seconds and about 90 minutes.