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Chronobiol Int. 2018 Aug;35(8):1175-1178. doi: 10.1080/07420528.2018.1458316. Epub 2018 Apr 16.

Evening types demonstrate reduced SSRI treatment efficacy.

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a Monash Institute of Cognitive and Clinical Neurosciences and School of Psychological Sciences, Monash University , Melbourne , VIC , Australia.


Selective serotonin reuptake inhibitors (SSRIs) have a profound effect on the circadian system's response to environmental light, which may impact treatment outcomes for patients depending on their habitual light exposure patterns. Here, we investigated the relationship between time-of-day preference, depressive symptoms and self-reported antidepressant treatment response. Evening types reported having taken a higher number of antidepressant medications in the previous 5 years and lower SSRI efficacy than morning types. While undergoing SSRI treatment, evening types also reported more depressive symptoms and suicidality. It is concluded that time-of-day preference may prove informative in predicting SSRI treatment responses.


Antidepressants; Chronotype; Circadian rhythms; Depression; Mood

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