Light pulses of 30 min. in the morning on three consecutive days, in a home setting, in combination with dim light during the evenings, can be part of an efficient phase advancing chronotherapy protocol to shift the biological clock. It is well known from controlled laboratory experiments, that light in the morninge induces phase shifts of the biological clock. In the study presented in this paper, short light pulses of high intensity blue light were tested in a home setting. After three consecutive days with 30 min blue light pulses, early in the morning, the melatonin rhythm advanced 49 minutes. This shift was not significantly different from three days with 60 min light pulses (59 min advance of melatonin).