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Comment by DickingAround | Hacker News Reader

Do trees actually 'sleep'? Like they don't have neural centers that we consider to be brain-like, that I know of. Further, just defining the concept of sleep is a little tricky and I'm not aware of anything like sleep-ish brain waves, or not moving for a long period of time that we consider sleep-like in trees.

So this idea of sleep evolving in two different species whose ancestor didn't sleep is very interesting.

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Trees definitely sleep nightly and hibernate in winter [0]. Their root system and the mycelial network that interoperates with them is astoundingly complex and looks very similar to a brain as we faster moving life are blessed with on top.

Here is a lady talking about some of Paul Stamets' research. [1] I also recommend this talk by him. [2]

Mushrooms interacting with plant roots look similar to a brain and we are just beginning to grok how deep that goes.

[0] https://onetreeplanted.org/blogs/stories/trees-sleep-night

[1] https://www.youtube.com/watch?v=1Q0un2GPsSQ

[2] https://q.sustainability.illinois.edu/a-fungal-estrangement/

>Trees definitely sleep nightly

We're equivocating the term "sleep" here. Trees have a nightly cycle, but it's not sleep in the sense that I go to sleep at night.

I don't necessarily buy that this is equivocating anything. How else would you define sleep scientifically other than as a nightly cycle that follows a circadian rhythm and propagates metabolic and hormonal changes throughout the body?

If you're trying to argue that it needs to have a "rest" component to it, I would remind you that during night time, trees do not photosynthesise and also the human brain is not at all at rest during sleep in terms of objective neurochemical activity. Consciousness is lost (except even this is a hazy cut off thanks to dreams) but there is a lot going on still in the brain and body.

How do you expect plants to photosynthesize at night without light. I don't think that holds up

That's a fair rebuttal, my bad. However, one thing that plants do more during the night without any bio-mechanical necessity attached to it is the release of auxin which is the flora analogue to growth hormone, just like animals do during sleep.

I guess you're catching up on the conversation. I don't think you know that much about tree sleep.

> So this idea of sleep evolving in two different species

You're assuming sleep comes after consciousness. Whatever sleep and dreams are, it's entirely possible they are the precursor to consciousness, not an evolutionary step off of consciousness.

Very concise. ^^ This guy dreams ^^

I’ve heard it said that trees are upside down people, with a “head” buried in the earth. It’s a flawed metaphor of course but it gets people thinking.

There’s been some interesting experimental research on how certain plants respond to stimuli and taproot lobotomies. These seem to be evidence for the equivalent of a brain-like computational center in plants. https://en.m.wikipedia.org/wiki/Plant_cognition is a good jumping-off point.

For a long time, people thought that applying terms like cognition and intelligence to plants and mold was anthropomorphizing, but nowadays it might be seen as animal-centrism, to proclaim that cognition and intelligence are exclusively within the domain of the animal kingdom.

Similar to what you find interesting here, plants seem to have evolved computational structures that are similar to our neural system, in that they have stimuli responses that are biased genetically, but that can also adapt to lived experience via hormonal feedback loops that serve as a kind of memory.

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