Computer models of cress plants genes showed how 12 genes work together to set plants’ internal clocks, University of Edinburgh researchers said.
They found that a protein, known as TOC1, previously associated with helping plants to wake up, dampened down gene activity at night.
Professor Andrew Millar said “it was a big change in thinking”.
Plants, animals and even bacteria go through a daily 24-hour routine, known as a circadian rhythm, which allow them to make tiny adjustments as daylight changes, and adapt to changing seasons.
Prof Millar said: “Just like humans you should think about plants having rhythms.
“Having a biological clock is particularly important for plants to prepare for daylight and at night-time [to] store energy for growth.
“We now understand how the dozen or so genes work and are typical to particular times of the day,” he said.