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Plants increase their respiration at night and stop photosynthesizing. https://www.bbc.co.uk/bitesize/guides/zxtcwmn/revision/1 https://www.bbc.co.uk/bitesize/

Plants increase their respiration at night and stop photosynthesizing. https://www.bbc.co.uk/bitesize/guides/zxtcwmn/revision/1 https://www.bbc.co.uk/bitesize/guides/zxtcwmn/revision/1 It seems kind of like sleeping to me.

ASalazarMX 5y ago
Although without sunlight, they have no choice but to stop photosynthesizing. Then we have plants like the dracaena fragans, whose flowers remain closed at day, but open and release their delicious fragrance all night. I'm not sure how sleep would work for her. https://en.wikipedia.org/wiki/Dracaena_fragrans https://en.wikipedia.org/wiki/Dracaena_fragrans
- periheli0n 5y ago
  Daytime sleeping is not unheard of.
einpoklum 5y ago
Nitpicking: "stop photosynthesizing" is just a direct consequence of the lack of ambient light. People stop getting sunburn at night, that's not part of "sleeping". Other than that: +1.
- wombatmobile 5y ago
  Well, you raise a non-trivial point that is more than just a semantic issue, viz what do we mean by "sleep"?
- ivanhoe 5y ago
  Plants physiology changes significantly during the night, so it's not just "no more photosyntheses without Sun"... respiration rates at night are strongly correlated with the amount of stored carbon and sucrose in the leaf tissue, which is probably related to the fact that plants also grow faster at night.
- DoreenMichele 5y ago
  Maybe not. Plants have two sources of nutrition: uptake via their roots and photosynthesis. My general understanding is that photosynthesis is what provides them energy whereas uptake via roots provides water and some essential nutrients they can't synthesize. The details will vary and some plants, for example, grow in total darkness or feed parasitically on other plants. But I think photosynthesis is roughly the equivalent of humans eating carbs for energy. So it's a little like saying "One defining characteristic of sleep is that animals stop eating." And, in fact, hibernation through the winter when food is in very limited supply is a known mechanism of survival for some species in harsh climates: They sleep instead of eating. In fact, my understanding is that to some degree eating and sleeping are substitutable. If you can't sleep, you can eat to help keep yourself functional while awake on a long shift. I think they do this on episodes of Deadliest Catch: feed people more when they are pulling a long shift and going to be awake for 24 hours straight.
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Florin_Andrei 5y ago
I mean, that's like 99.9999....% expected, since they all evolved with a big light signal in the sky that operates on a 24 hr cycle. Plants, even more than animals, should be optimized to function that way (do mostly resource production at day, do mostly maintenance at night).
dan-robertson 5y ago
One difference at night is that it is cooler, so less water may be lost when the stomata are opened for gas exchange. Many plants (separately) evolved a photosynthesis cycle where gases need only be exchanged at night and the stomata may be closed during the day.[1] While the actual photosynthesis reaction happens during the day, the nighttime preparation is needed, and should perhaps be counted towards the effort. https://en.m.wikipedia.org/wiki/Crassulacean_acid_metabolism https://en.m.wikipedia.org/wiki/Crassulacean_acid_metabolism

ASalazarMX 5y ago

Although without sunlight, they have no choice but to stop photosynthesizing. Then we have plants like the dracaena fragans, whose flowers remain closed at day, but open and release their delicious fragrance all night. I'm not sure how sleep would work for her. https://en.wikipedia.org/wiki/Dracaena_fragrans https://en.wikipedia.org/wiki/Dracaena_fragrans

periheli0n 5y ago
Daytime sleeping is not unheard of.

einpoklum 5y ago

Nitpicking: "stop photosynthesizing" is just a direct consequence of the lack of ambient light. People stop getting sunburn at night, that's not part of "sleeping". Other than that: +1.

wombatmobile 5y ago
Well, you raise a non-trivial point that is more than just a semantic issue, viz what do we mean by "sleep"?
ivanhoe 5y ago
Plants physiology changes significantly during the night, so it's not just "no more photosyntheses without Sun"... respiration rates at night are strongly correlated with the amount of stored carbon and sucrose in the leaf tissue, which is probably related to the fact that plants also grow faster at night.
DoreenMichele 5y ago
Maybe not. Plants have two sources of nutrition: uptake via their roots and photosynthesis. My general understanding is that photosynthesis is what provides them energy whereas uptake via roots provides water and some essential nutrients they can't synthesize. The details will vary and some plants, for example, grow in total darkness or feed parasitically on other plants. But I think photosynthesis is roughly the equivalent of humans eating carbs for energy. So it's a little like saying "One defining characteristic of sleep is that animals stop eating." And, in fact, hibernation through the winter when food is in very limited supply is a known mechanism of survival for some species in harsh climates: They sleep instead of eating. In fact, my understanding is that to some degree eating and sleeping are substitutable. If you can't sleep, you can eat to help keep yourself functional while awake on a long shift. I think they do this on episodes of Deadliest Catch: feed people more when they are pulling a long shift and going to be awake for 24 hours straight.

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Florin_Andrei 5y ago

I mean, that's like 99.9999....% expected, since they all evolved with a big light signal in the sky that operates on a 24 hr cycle. Plants, even more than animals, should be optimized to function that way (do mostly resource production at day, do mostly maintenance at night).

dan-robertson 5y ago

One difference at night is that it is cooler, so less water may be lost when the stomata are opened for gas exchange. Many plants (separately) evolved a photosynthesis cycle where gases need only be exchanged at night and the stomata may be closed during the day.[1] While the actual photosynthesis reaction happens during the day, the nighttime preparation is needed, and should perhaps be counted towards the effort. https://en.m.wikipedia.org/wiki/Crassulacean_acid_metabolism https://en.m.wikipedia.org/wiki/Crassulacean_acid_metabolism