Light can ameliorate low mood in healthy people

Abstract

We greatly appreciate Emeritus Professor Kripke for his interest in our recent article (Hoaki et al. 2010) where it was revealed that higher illuminance of daytime, greater fluctuation in sleep time, and lower central serotonergic function significantly and independently predicted hyperthymic tendency.In response to the inquiry from Emeritus Professor Kripke, we investigated the association between illuminance of daytime and Hamilton depression rating scale (HAM-D) scores and that between illuminance of daytime and Young mania rating scale (YMRS) scores. As a result, there was a significantly negative association between illuminance of daytime and Hamilton depression rating scale scores (rho=−0.23, p=0.035), but no significant association between illuminance of daytime and YMRS. It should be noted that our subjects were healthy volunteers, and their range of HAM-D and YMRS was 0-6 and 0-4, respectively. Therefore, these scores were within normal limits. Nonetheless, the significantly negative association between illuminance of daytime and HAM-D scores indicate that light can ameliorate low mood in healthy people. These findings are in accordance with the report from Kripke's group (Espiritu et al. 1994). Further studies are required to prospectively investigate whether light can prevent the occurrence of depression in healthy people. References

"Light Modulation Therapy" for Bipolar Disorder

“…As such, it can be hypothesized that light exposure, whether it is dim or bright, may bring about an antidepressant effect. In line with this hypothesis, findings from our research group have shown that environmental light was directly associated with mood [3] and that total annual sunshine was inversely associated with suicide rate [4].…”

Natural Light Exposure, Sleep and Depression among Day Workers and Shiftworkers at Arctic and Equatorial Latitudes

“…Accordingly one additional innovative health promoting strategy would be to increase time outdoors, by including breaks during the work hours that can be spent outdoors, for instance. This non-pharmacological intervention could likely prevent, minimize or even reverse the health problems associated with circadian disruption and sleep deprivation [ 5 , 14 , 15 ].…”

A Review on the Role of Color and Light in Affective Computing

“…The following findings inform about some further aspects of light perception. A significantly negative association between illuminance during daytime and Hamilton depression rating scale scores has been described [53]. On the contrary, no significant association between illumination in daytime and young mania rating scale has been found.…”