Can plants kill you at night?

Hello plant fans. I was having a chat over a glass of wine with my neighbor out the other day, the usual. She was asking me how I have the time to take care of so many plants.

One thing led to another and she noticed that I have a lot of plants in my bedroom, so her immediate reaction was to tell me that was dangerous.

She told me that during the night plants take in oxygen, so her concern was that my plants were taking oxygen out of the room at night-time and they could go so far as to choke me in my sleep.

I really appreciate her concern, but it reminded me that this is a belief that a lot of people hold.

In fact, even my grandma when I was a child wouldn’t keep plants in the bedroom for the same reason. I also have heard about plants being removed from hospital rooms because of this same belief.

I’m sure a lot of you are familiar with this story, so let’s answer this one once and for all.

Is it true? Can plants kill you at night?

There is absolutely no chance your houseplants can breathe your oxygen and kill you. While most plants respire at night, meaning they take oxygen in and release carbon dioxide, overall they release more oxygen than they take in, which means oxygen levels will only increase.

Also, the amount of oxygen plants breathe in is much less than what a human or a pet does, so you have nothing to worry about.

The reason why this myth still persists is because of the misunderstanding of photosynthesis.

We were shown diagrams since we were children of photosynthesis being equal to respiration in plants, so people tend to think of it as always a reverse phenomenon which is not true.

While it is true that a single leaf plant will produce the same amount of oxygen as carbon dioxide, plant respiration happens at a slower pace than photosynthesis, which means that for every cycle you have a tiny gain of oxygen.

Otherwise, the plant wouldn’t grow.

You have probably seen the diagram above many times, but they usually don’t show the speed difference between respiration and photosynthesis.

So now that we got that out of the way, what if we are talking about a lot of plants confined into a small space? Let’s dig into that a bit.

Let’s make this thought experiment because at the end of the day, plants technically still take oxygen during the night.

What if I live in a really small room and I fill it up with plants just for the night?

So, theoretically, they haven’t given any oxygen during the day but they will take oxygen during the night. In this scenario, let’s assume we use as many plants as possible, can too many plants kill you?

The answer is no. It doesn’t really matter how many plants you have in a small room. It isn’t possible to put that many plants into the room that they eventually harm or kill you through oxygen deprivation.

It is actually more deadly not to have plants in your bedroom. Let me explain this with some numbers.

The part of the plant that does photosynthesis and respiration is the leaf. Let’s completely ignore the fact that they give off more oxygen than they consume for now.

I personally sleep in the same room with my dog and my husband. If we add up their weights, we would have around 220 pounds so 100kg of hairy cuteness.

If we calculate how many plants we would need using the ratio above, we would need 22.000 pounds (10.000kg) of plants in the same room just so the breath in the same amount of oxygen as my husband and my dog does.

We can make a nice round number and say we would need 1000 plants weighing in at 22 pounds each (10kg) counting the soil, stem, and roots, just to consume as much as a big adult in the room. Wow, those are a lot of plants even for me.

So I hope that settles it and gives you some peace of mind.

But wait, there is another problem with this. Too much oxygen can also harm or kill you.

We already established that plants give off more oxygen than they use, so, could plants theoretically produce so much oxygen that they can give you oxygen poisoning?

In this case I won’t even go in detail with the calculation because the positive output of oxygen it’s small when it comes to your average plant in 24-hours. You will also need to achieve a 100% oxygen level.

Spoiler alert, you need about 660 million average plants in a small room in order to kill someone with oxygen poisoning.

Not only is that impossible because of the sheer number of plants, but they would need carbon dioxide and light to make it work, which means the plants will end up dying before killing the person.

So, there you go, no real amount of plants can kill you by taking or giving too much oxygen.

But maybe there are certain situations where you should avoid having plants in your bedroom, let’s explore that further.

Is it bad to sleep with plants in your bedroom?

No it’s not. It is not bad for you to sleep with plants in your bedroom if you are a healthy adult and your houseplants are healthy.

Not only is it not bad but it’s actually really good for you. I can personally attest that plants can actually help a lot with sleeping and breathing better.

There also have been multiple studies done that suggest plants can actually help a lot while sleeping.

Plants will increase oxygen levels in your room while reducing carbon monoxide and carbon dioxide, which helps a lot with sleep apnea and asthma.

Plants also reduce quantities of natural toxins like methane and formaldehyde. They can act as filters reducing harmful pollutants that are inescapable in modern life and will help you with better breathing.

Houseplants can also add a pleasant scent and color to your room, which helps with depression, anxiety, and improves cognitive functions and sleep quality.

The benefits that houseplants can have on your life are hard to overstate and having asthma myself, I can sincerely say that I sleep and feel much healthier having plants in my room.

This being said, there are certain special conditions where you might not want to have plants in your bedroom, like these ones:

 
  • If you have hay fever, avoid plants with an overpowering scent.

  • If the plant is not healthy and suffering from fungus or has mold in the soil. You need to be extra careful with this if you have asthma or allergic reactions.

  • A couple of plants that you might want to avoid having in your room if you have small children or pets because they are toxic if ingested and have a history of being appealing to eat.

Although this can be a long list, I will state those that are common houseplants and which look appealing to pets:

Plant name Avoid because
Daffodil (Narcissus) Toxic bulbs that can cause dermatitis if you touch them and are toxic if consumed. They cause stomach upsets and vomiting with the most severe reactions on this list.
Caladium (Elephant ear) They are toxic if consumed causing burning in the throat and mouth. Their leaves can look pretty spectacular, inviting pets or children to stick them in their mouths.
Devil’s ivy (Pothos) They look harmless and are safe to the touch, but toxic if consumed. Pothos cause pain, swelling and vomiting to both pets and humans.
Dumb cane Toxic if consumed and apparently it happens often enough to give the plant its name. The effects are swelling of the tongue and mouth with difficulty speaking.
Peace lily Safe to touch, but toxic if consumed. They are pretty and smell good, so if you have pets or small children avoid them as they might want to munch on them.

There are tons of alternatives to these ones, and if you don’t have any pets or small children or the impulse of eating them, you are still safe to have them in the bedroom.

Especially Peace Lilies, who have a great scent at night and how the now-famous NASA experiment showed, are great at cleaning the air.

If you have an interest and want to read more here is the experiment quick overview.

Do plants take in oxygen at night?

Yes, during the night, plants enter a process called respiration, where they use oxygen by combining it with the food they create during photosynthesis to produce the energy they need for growing.

But the truth is, plants respire all the time, night and day.

The result of the process is carbon dioxide, so you can say respiration is the opposite of photosynthesis.

Wait, what? But I thought plants only take oxygen at night, how can we test this?

If you have the time, I suggest you try out the following very simple experiment.

Plant respiration experiment

  • Take your favorite houseplant, if it’s too big, take a smaller one.

  • Take a shallow bowl of water. It’s easier to spot if it is transparent or has a darker color.

  • Make sure you have sunlight available, so we can actually test respiration during the day.

Step 1

Submerge one leaf of the plant underwater. It will try to float but try to keep at least one leaf completely submerged.

Step 2

Put the bowl and the plant in the window or in a place it gets sunlight.

Step 3

Leave it for one hour.

Step 4

Look at the leaf surface underwater. You will see a few small bubbles as the plant respires.

There you go, plants use oxygen all the time, so the myth that plants can kill you at night really stands on nothing at this point.

To make things even better, there are houseplants that give oxygen 24 hours a day, so if you really want to make sure you get the best benefits, keep the next houseplants in mind.

Houseplants that give oxygen at night

Yes, you’ve read this right, there are popular houseplants that will give oxygen even during the night.

Gerbera

Gerberas are absolutely perfect if you are picky. They are non-toxic and easy enough to take care of. They are also scentless so If you suffer from hay fever, there is nothing to worry about. Besides the non-stop oxygen, they also flower and give a beautiful spark of color to your room that can help with anxiety and depression.

Aloe Vera

Aloe Vera needs no introduction. In my personal opinion, it is one of the best houseplants anyone could own. Besides the amazing properties Aloe Vera has, it also gives oxygen during the night. The latex is toxic if you or your pet ingest but for some reason, I have yet to hear of a pet eating Aloe Vera on its own.

Snake plant

Similarly to Aloe Vera, snake plants can be mildly toxic if ingested, but the truth is it doesn’t happen too often. There is something about snake plants that it just isn’t yummy to pets. They are also great rugged plants that can outstand almost anything and clean the air like almost no other.

Areca palm

Areca palms are more popular than ever and it might be the time you get one too.

The reason why I recommend them is that they can get pretty big and can single-handedly satisfy the need for a plant in the bedroom. You can only have one areca palm in the corner of your bedroom and you’re good to go, it will clean the air even during the night and also give oxygen.

There are tens or hundreds more, including the Peace Lily, mentioned above, but as it is a bit more toxic and some pets find it yummy I decided to go against it.

If you are in the mood of reading a bit of science today, you can check out this official NASA paper on the benefits of houseplants

I really hope this puts an end to this internet myth and we all get to enjoy a bit more plants in our lives.

Related Posts