[1] He then completed a postdoctoral fellowship at the National Science Foundation (NSF) Center for Biological Timing at the University of Virginia under the guidance of Steve A. Kay and Gene D. Block in 1995.
In 1996, he joined the faculty of the University of Warwick, where he began to work on synthetic and systems biology in conjunction with plant chronobiology.
Millar helped found SynthSys, a centre for synthetic and systems biology research partnered with the University of Edinburgh, in 2007.
Millar began experimenting with the firefly luciferase reporter gene as a graduate student at The Rockefeller University.
[5] The mechanisms underlying the oscillator's function, specifically the full extent of "ELF3" and "ELF4"'s interactions with other parts of the clock, are an active area of research.
In 2005, Millar and his colleagues discovered how plant circadian clocks increase photosynthesis and growth, thereby offering a selective advantage.
In 2017, Millar and colleagues quantitatively explained and predicted canonical phenotypes of circadian timing in a multicellular, model organism.