The researchers, led by Dr Stuart Peirson from Oxford's Sleep and Circadian Neuroscience Institute were aiming to understand why exposing mice to bright light caused two - physically incompatible - responses.
Dr Peirson explained: 'When we expose mice to light during the night, it causes them to fall asleep. Yet, at the same time, it also increases levels of corticosterone, a stress hormone produced by the adrenal gland that causes arousal - wakefulness. We wanted to understand how these two effects were related and how they were linked to a blue light-sensitive pigment called melanopsin, known to play a key role in setting our body clock.'