TREES do not always sleep like a log and toss and turn in the night, new research suggests.

High-precision three-dimensional surveying of 21 species of trees revealed a previously unknown cycle of subtle canopy movement during the night.

These cycles even differed from one species to another, according to the findings.

Researchers say the detection of anomalies in overnight movement could become a future way of identifying stress or disease in crops.

One of the most important processes sustaining life is the transport of water from the ground to the leaves where photosynthesis and capture of the sun’s energy take place.

Overnight movement of leaves is well known for tree species belonging to the legume family, but it was only recently discovered that other trees also lower their branches by up to four inches at night and then back in the morning.

Reseachers explained the branch movements are slow and subtle, and take place at night, which makes them difficult to identify with the naked eye.

Doctor András Zlinszky, of Aarhus University in Denmark, said: “The movement has to be connected to water pressure. Water transport is not just a steady-state flow, as we previously assumed”.