Biological aspect of hyperthymic temperament: light, sleep, and serotonin

Abstract

The present findings suggest that light, sleep, and serotonin are crucial factors in understanding hyperthymic temperament, which may be common to bipolar disorder.

Does temperature or sunshine mediate the effect of latitude on affective temperaments? A study of 5 regions in Japan

“…More importantly, Hoaki et al (2011) reported that the greater illuminance of daytime independently predicted higher hyperthymic temperament scores via a multiple regression analysis. That study measured the illuminance that each participant received using actigraphy.…”

“…This interesting "latitude effect" on affective temperaments was recently confirmed by our subsequent extension study of three regions with different latitudes that indicated a dose-response relationship between hyperthymic temperament and sunshine and latitude (Kohno et al, 2014) (our unpublished data). Hoaki et al (2011) reported that more hyperthymic participants receive more light. In addition, more hyperthymic participants prefer brightness and dislike darkness compared with less hyperthymic participants, suggesting the presence of heliotropism (Harada et al, 2013).…”

Light can ameliorate low mood in healthy people

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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.

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“…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.…”

Age-at-onset and comorbidity may separate depressive disorder subtypes along a descending gradient of bipolar propensity

“…These data suggest that some temperamental profiles and/or association of temperamental traits may condition the more or less early occurrence of comorbidities which could themselves constitute risk factors for the further development of affective disorders. For instance, individuals carrying the S allele of the serotonin transporter gene, show high concentration of serotonin in the synaptic cleft and are frequently found among subjects with depressive temperamental traits [67] and/or those with heightened anxiety [68]; in contrast individuals with hyperthymic temperament seem to be characterized by lower central serotonergic function [69] and overrepresented among ADHD patients [70]. Moreover the L allele of the serotonin transporter gene was shown to be a risk factor for the development of ADHD [71].…”