Mismatched light and heat levels can disrupt body clock

Body clock function can break down when light and temperature levels throughout the day are out of sync, finds new UCL research in fruit flies. The study, published in Cell Reports, examined the activity levels of flies when they were exposed to light and heat at different times. The 'natural' cycle involved 12 hours of light and warmth followed by 12 hour of darkness and cold. The light and temperature cycles were then varied so that the light cycle ran between two and 10 hours behind the temperature cycle in each experiment. When the time lag was small the effect on the body clock was relatively low, following an average of the light and temperature readings. When the time lag was large, temperature was ignored and the body clock was set by light. A moderate time lag of around six hours, however, caused the clock function to break down, with major disruptions to behaviour and clock-controlled molecular signals.