In the natural environment, all life is exposed to a daily cycle of light and dark fluctuation of light intensities and seasonal oscillation of daylight length as a result of the rotation of the planet. Eukaryotic and prokaryotic cells have evolved to respond to the rhythmic changes in environmental conditions and synchronize their cellular processes to the most appropriate time of the day (Dixon et al., 2014 and Duanmu et al., 2014).
In the natural environment, all life is exposed to a daily cycle of light and dark fluctuation of light intensities and seasonal oscillation of daylight length as a result of the rotation of the planet