Circadian Ecology: the regulation of circadian rhythms by the natural light environment

Due to the rotation of the earth on its axis, all life has evolved under 24-hour cycles in environmental conditions such as light levels and temperature. These have acted as strong selection pressures, resulting in many organisms evolving internally generated 24-hour cycles in physiology and behaviour. These are known as circadian rhythms, and span multiple levels of biological organisation from gene expression to sleep-wake patterns. This internal representation of the temporal environment, or so-called body clock, is only of adaptive value to an organism if it is aligned to the external environment; allowing individuals to anticipate, rather than simply respond to, regular changes in their environment. In mammals the primary environmental stimuli responsible for this synchronisation is light; a process known as photoentrainment. Light is a complex and dynamic environmental signal, varying in terms of intensity, spectrum (colour) and duration, as well as being influenced by the reflective properties of the local environment. However, in the field of circadian neuroscience light has become extensively simplified within the laboratory setting. Therefore, via the simulation of naturalistic light environments in the laboratory, this project seeks to combine visual ecology with circadian neuroscience in order to understand how the complex natural light environment regulates circadian rhythms.