(Mirror Daily, United States) – It is already known that almost all life on Earth depends on the 24-hour rule. Apparently trees sleep too. According to Michael Twery, lead researcher at the National Institutes of Health, in almost every organism and cell on Earth there are genes that code for a 24-hour circadian rhythm.

Therefore, rest is fundamental for all life. Scientists have discovered lately that biological clocks exist almost everywhere: in mice, fruit flies or single-cell organisms. But the latest one seems to be the most amazing.

Recent research discovered that trees might actually “sleep” at night. The experiment was done on two birch trees, one in Finland and one in Austria. Laser scanners were pointed by scientists on the trees to detect even the smallest change in its shape.

According to Eetu Puttonen, one of the study authors, during the night, the branches drooped around 10 centimeters, as if they were resting. Therefore, the tree seemed to relax each night for a few hours, starting from about two hours after sunset until just before sunrise when the tree appeared to wake up.

Because this is the first study that detected changes in tree branch geometry over a 24-hour-cycle, it is too early to determine whether this is a general rule or an exception. Further research must be conducted on other species of tree to test the effectiveness of the laser system in measuring plant circadian rhythms.

Scientists have previously managed to observe this process at smaller plants in the lab. However, it is a lot harder with big trees in the forest. But in the future, if this technique proves to be effective, Puttonen and his colleagues could see a whole forest winding its branches during the night.

Until now, there are two possible reasons why trees are drooping. First, because their internal water pressure drops at night in the absence of photosynthesis. Second, the trees are resting because raising the branches up toward the light during the day takes a lot of energy.

Regarding the conditions of the study, scientists chose a windless night at both locations, and conducted each measurement in September, near the vernal equinox, to have an equal duration between day and night.

According to Puttonen, this research will help them understand better how trees use water during the day and whether they sleep or not. Moreover, this will assist the rubber industry, where the sap of the tree is needed and also the timber industry where trees with low water content are used.

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