The aging effects on circadian rhythms have ranging implications from complex cognitive performance to simple physiological functions. These change includes changes in the pattern of rhythmic expressions, such as a wide fragmentation of the rhythm of activity-rest, decrease in amplitude and increase in the period of rhythm in the activity phase regulated by the suprachiasmatic nucleus (SCN). The light study on biological aspects has received great current interest, due, among some aspects, to its positive response in psychiatric disorders in humans. With this in mind, light therapy can be used to stimulate SCN to improve its functionality in an ontogenetic phase in which there are shown to be several circadian dysregulations, possibly due to damage to the circadian pacemaker. This study aims to evaluate, in aging rats, the effect of blue light therapy on the SCN functional aspects, through the evaluation of the activity-rest rhythm, as well as in possible changes at the central clock in neuronal and neurochemical levels. For this, 11 rats (Rattus novergicus) Wistar aging male aged approximately 16 months were used. The animals underwent continuous records of locomotor activity and periods of 6 hours of exposure to low intensity blue light (~ 150 lux; 470-490 nm) at the beginning of the light-dark cycle 12:12 h for 14 days. At the end of blue light therapy, six animals were perfused in ZT 6 or ZT 12 and five animals continued to record the rate of activity-rest for another 14 days, being perfused later at the same time. The animals, after exposure to low intensity blue light, presented changes in locomotor rhythmicity patterns. This indicates that blue light seems to have a positive effect, where it improved the rate of activity-rest of aging animals, particularly the robustness of the rhythm, daily stability of the acrophase and greater consolidation of the resting phase. These changes lasted days after the end of the blue light therapy, thus changing the rhythmic pattern of the aging animals in relation to its baseline. We hope that, after performing new behavioral experiments and histological evaluations, data will be generated that will elude whether the blue light phototherapy use in aging animals promotes an improvement in biological rhythms at a life stage where they suffer greatly from behavioral, neurochemical and cognitive changes.