Irradiance dependency of UV-A induced phase shifts in the locomotor activity rhythm of the field mouse Mus booduga.

In the nocturnal field mouse Mus booduga, the responsiveness of the circadian system to UV-A light of 2.5 W/m2 and 30 minutes duration is known to be phase dependent. The results of our experiments indicate that the phase shifts evoked by UV-A at the two phases, CT14 (circadian time 14) and CT20 increases nonlinearly with irradiance.