A bedtime alarm is there to wake humans up in the morning but for plants it may be a matter of life or death, new research suggests.

Scientists studied the arabidopsis flower – a member of the mustard family – and found that it uses a biological time-keeper to survive the night.

Plants use sunlight to make their own sugars from photosynthesis during the day and store them to provide energy during the night.

A metabolic signal adjusts their circadian clock in the evening, ensuring enough energy is conserved to survive the dark hours.

Dr Mike Haydon, formerly from the University of York, said: “We think this metabolic signal is acting rather like setting an alarm clock before bedtime to ensure the plant’s survival.

“Plants must co-ordinate photosynthetic metabolism with the daily environment and adapt rhythmic physiology and development to match carbon availability.”

The research, published in the PNAS journal, involves a set of genes known to be regulated by the chemical compound superoxide, a molecule associated with metabolic activity.

Professor Ian Graham, from the University of York, added: “Distinguishing the effects of light and sugars in photosynthetic cells is challenging.

“Our data suggest a new role for superoxide as a rhythmic sugar-related signal which acts in the evening and affects circadian gene expression and growth.”