The short answer
No houseplant produces oxygen for 24 hours a day in any meaningful net sense. Plants make oxygen when light drives photosynthesis, and they use some oxygen in respiration around the clock, as animals do. A few plants, such as snake plant and aloe, have a modified way of handling carbon dioxide that shifts when they take it in. That is where the idea of “24-hour oxygen plants” comes from. It does not mean they supply extra oxygen to a sleeping person.
How plants make and use oxygen
During the day, a plant in light takes in carbon dioxide and releases oxygen as part of photosynthesis. At the same time, the plant’s cells use oxygen for respiration, which is how they get energy from stored sugars. In light, photosynthesis usually outweighs respiration, so there is net oxygen release. In the dark, photosynthesis stops, and the plant only respires, so it takes in a small amount of oxygen and releases a small amount of carbon dioxide.
The quantities in a normal room are very small. Room air is roughly one-fifth oxygen, and air moves in and out of homes constantly through gaps, doors, and windows. A few houseplants do not change what you breathe in any way you could measure without instruments.
What CAM plants actually do at night
Most plants open the pores on their leaves (stomata) in the daytime. CAM plants, including many succulents, snake plant, and aloe, tend to open them at night, when the air is cooler and less water is lost. They take in carbon dioxide at night and store it chemically, then use it for photosynthesis during the day when the stomata are closed.
That is the real fact behind the “night oxygen” claim. But the light-dependent step that actually releases oxygen still happens in the daytime. So a CAM plant is not a night-time oxygen source. It changes the schedule of its gas exchange; it does not create a stream of oxygen at night. Some plant sellers describe it as if it does, and we would treat those claims with caution.
Plants often called night-oxygen plants
These plants are commonly recommended under this label. They are fine houseplants for other reasons, but none should be bought as an oxygen supply.
- Snake plant (Dracaena trifasciata): very tolerant of low light and dry spells (see easy low-light houseplants). Toxic to cats and dogs if chewed.
- Aloe vera: needs bright light and little water. Toxic to cats and dogs if eaten.
- Christmas cactus (Schlumbergera): grown for its flowers (see flowering cactus houseplants). Generally listed as non-toxic to cats and dogs.
- Orchids: many popular orchids are moth orchids (Phalaenopsis), which use CAM-style gas exchange. They are generally listed as non-toxic to cats and dogs.
- Jade plant and other succulents: common examples of CAM plants (see are succulents indoor or outdoor plants). Jade plant is toxic to cats and dogs.
If you share your home with pets or young children, check the toxicity of any plant before bringing it in, and keep potentially harmful plants out of reach. Contact a veterinarian or poison control if a plant has been chewed or swallowed. For bedroom-specific suggestions, see the best plants for bedrooms.
How many plants would it take?
Charts that rank houseplants by “oxygen production” often rely on rough estimates, and different sources give very different numbers. Reviews of the research on indoor plants and air have generally concluded that the number of plants needed to change room air in a noticeable way is impractical for a home. We do not give a plant-count here because we cannot support a precise figure. The takeaway is that houseplants are not a practical way to raise indoor oxygen.
How to get fresher air in a bedroom at night
If a room feels stuffy, the cause is usually a build-up of carbon dioxide and moisture from the people breathing in it, and the fix is ventilation, not plants.
- Open a window slightly, if outdoor air and noise allow it.
- Leave the bedroom door ajar to allow air to circulate.
- Use a ventilation fan or a system designed for the room, if you have one.
- Keep the room dust-free and avoid sources of indoor pollution such as smoking or burning candles in a closed room.
If you have breathing problems, talk to a doctor rather than relying on plants. For a broader look at plants and air quality, read best indoor plants for breathing easier.
What produces most of the world’s oxygen?
Globally, photosynthesis by plants on land and by tiny algae and bacteria in the oceans produces the oxygen in the atmosphere. Marine phytoplankton are often credited with roughly half of it, and some popular sources say more. Estimates vary, so we would treat any single percentage with caution.
FAQ
Which plants release oxygen at night indoors? None in a net, meaningful way. CAM plants such as snake plant and aloe take in carbon dioxide at night, but oxygen release still depends on light.
How do I increase oxygen in a room at night? Ventilate. A slightly open window or door is more effective than any number of houseplants.
Is it unsafe to sleep with plants in the room? For most people, no. Plants use only a tiny amount of oxygen at night. The more realistic concerns are toxic plants near pets or children and soil mold for sensitive people.
Do more leaves mean more oxygen? In light, a bigger healthy plant does more photosynthesis, but the effect on a room’s air stays negligible.