Figure 1.

Circadian clock main components and the interplay between circadian time assessment and chronotherapy. (A) The internal clock is composed of central and multiple peripheral clocks, sharing a common molecular network of transcription/translation feedback loops. (B) Multiple methods are used to assess internal circadian rhythms including chronotype evaluation questionnaires and various biological samples that can be collected to assess hormonal concentration and gene expression profiles. Time-of-day treatment adjustment in alignment with the internal circadian clock of the body has been reported to increase effectiveness and decrease toxicity of treatment.