Evening types demonstrate reduced SSRI treatment efficacy

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


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.

Keywords: Antidepressants; Chronotype; Circadian rhythms; Depression; Mood.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activity Cycles*
  • Adolescent
  • Adult
  • Affect / drug effects*
  • Aged
  • Antidepressive Agents / adverse effects
  • Antidepressive Agents / therapeutic use*
  • Circadian Rhythm*
  • Depression / diagnosis
  • Depression / drug therapy*
  • Depression / physiopathology
  • Depression / psychology
  • Drug Resistance
  • Female
  • Humans
  • Male
  • Middle Aged
  • Phenotype
  • Selective Serotonin Reuptake Inhibitors / adverse effects
  • Selective Serotonin Reuptake Inhibitors / therapeutic use*
  • Time Factors
  • Treatment Outcome
  • Young Adult


  • Antidepressive Agents
  • Serotonin Uptake Inhibitors