LIght therapy to shift the biological clock has been shown to be effective, but in most cases studies are carried out in well controlled laboratory studies and with long duration light pulses. In practice, light therapy should consist of an easy to apply lighting regime to which people at home will adhere and with clear effects, irrespective all other environmental light exposure. In this study the effect of 30 min of blue light in addition to instructions to advance sleep at home, during a 9-day protocol was tested and compared to a group who received the same instructions but with amber light treatment. The group with late chronotypes who were motivated to advance their sleep and received blue light showed a larger phase advance of the rhythm of melatonin compared to the motivated group who receiverd amber light treatment. One week post-treatment, the group who received blue light still woke up earlier compared to the group who received amber light. Sleep at night and performance during the day were worse during treatment in the amber light group. In the blue light group, this worsening of sleep was nog observed and performance was only worse immediately after waking up compared to the same time point in the baseline weeks. in the paper, we conclude that blue light treatment at home is effective in shifting both the biological clock and in shifting sleep, while preventing a worsening of sleep and daytime performance during a sleep phase advancing protocol. DOI: 10.1177/0748730416657462