Do trees really sleep?

Imagine making your food, consuming it and repeating the process over and over again – all without even touching it. Sounds tiring, right? Well, that’s photosynthesis and it’s all in a day’s work for trees.

But how tiring is this for a tree? And does the tree require an hour or two of well-deserved rest for all this work?

The answer is yes. Trees do rest and trees do sleep – just not like you and me. What is similar between us, however, is the circadian rhythm. You’ve probably heard this term used synonymously with the term ‘body clock’. This rhythm unites all life on the planet. This includes us and yep, it even includes trees. To refresh your memory, the circadian rhythm is a natural, internal process that regulates the sleep-wake cycle that repeats with each rotation of the earth, roughly every 24 hours. And this circadian rhythm holds the answer to the sleep patterns of trees.

The most famous experiment strewn across the internet is of two birch trees. But, these aren’t trees growing a few feet away from each other or even in the same forest. One birch tree was located in Austria while the other was in Finland. Scientists studied both these trees and noticed that both trees seemed to relax for a few hours each night. To be specific, about two hours after sunset till just before sunrise. Also, as the night progressed, branches of both trees drooped as much as 10 centimeters. But, why are the trees drooping? One reason could be that they’re dropping their internal water pressure as there’s no photosynthesis to conduct while another reason could be that the trees are actually resting and conserving energy. This experiment is the first of its kind conducted on large trees. Researchers have conducted millions of such experiments on small plants before and even Darwin noted that leaves, in fact, do “sleep” at night.

Why spend countless hours (and money) to research whether trees sleep or not? While felling trees, it is important for trees to have lesser water content, which affects the quality of wood positively. But, beyond finding out whether trees enjoy naps as much as we do and whether we’re getting the best out of the timber industry, it is to showcase how light affects all life. More than exhaustion, it is the circadian rhythm that dictates when we should sleep and when we should be active. The same goes for trees too. This means that there’s a whole lot more to the connection between you, trees, light, darkness, and even entire forests. 

Tonight, as you retire to bed, look out the window and see if you can spot a tree. Chances are, it’s probably called it a night and is happily snoozing, ready to take on the next day – just like you should too.