Carl Hirschie Johnson is an American-born biologist who researches the chronobiology of different organisms, most notably the bacterial circadian rhythms of cyanobacteria.

Johnson asserts that "music led [him] to science," as he originally began his research job with Menaker to pay for classical voice lessons.

[2] He went on to earn his Ph.D. in biology in 1982 at Stanford University, first working under the renowned leader in chronobiology, Colin Pittendrigh and then moving to David Epel's laboratory to finish his degree.

[2][3] Johnson's initial foray into research was as an undergraduate in Menaker's lab, which was working on the pineal gland in birds[7][10] and other chronobiology projects in vertebrates.

[8] In graduate school at Stanford under Colin Pittendrigh, Johnson attempted to discover circadian rhythms in a variety of organism such as leeches and cockroaches.

[15][16] In his postdoctoral studies with Hastings, Johnson returned to the biological clocks field and worked mainly on rhythms in the bioluminescent alga Gonyaulax polyedra[17][18] and later in the algal model system for genetics, Chlamydomonas reinhardtii.

The Johnson Lab is currently applying biophysical methods to explain how the central bacterial clock proteins (KaiA + KaiB + KaiC) oscillate in vitro.

[26][29][30] Together with the laboratory of Dr. Martin Egli, Dr. Johnson's lab has led a concerted effort to apply structural biology techniques for insight into circadian clock mechanisms.

[28] Finally, Johnson and his lab is studying circadian and sleep phenotypes of mouse models of the serious human neurodevelopmental disorder called Angelman syndrome.