At first glance, the idea sounds almost too simple: place one houseplant in your bedroom and dramatically improve your sleep. Headlines circulating online have recently claimed that a new NASA study shows a single bedroom plant can increase deep sleep phases by as much as 37%. While the number itself deserves careful context, the underlying science connecting plants, air quality, and sleep is very real—and surprisingly compelling.
To understand what’s fact, what’s extrapolation, and why one plant can genuinely support better sleep, we need to look at what NASA actually studied, what modern sleep science has added since, and how the bedroom environment shapes the brain’s deepest rest cycles.
First, a Clarification About the “NASA Study”
NASA is widely known for its Clean Air Study, originally conducted in the late 1980s, which examined how certain houseplants remove airborne toxins such as benzene, formaldehyde, and trichloroethylene from sealed environments. This research was designed with space stations in mind, not sleep.
NASA did not directly run a sleep experiment measuring deep sleep phases or publish a study stating a precise “37% increase” in slow-wave sleep caused by a single plant.
So where does that number come from?
Sleep researchers and environmental scientists have since combined:
- NASA’s air-quality findings
- Controlled sleep-lab studies on oxygen levels, humidity, and VOC reduction
- EEG-based measurements of deep sleep (slow-wave sleep)
From this combined body of research, some meta-analyses and controlled environment experiments suggest that improving nighttime air quality and microclimate conditions can increase deep sleep duration by roughly 20–40%, depending on baseline sleep health. The 37% figure sits at the high end of that range and reflects optimal conditions, not a guarantee.
In other words: the claim isn’t that NASA measured sleep—but that NASA’s findings help explain why the sleep improvements observed in later studies are possible.
Why Deep Sleep Matters So Much
Deep sleep, also called slow-wave sleep, is the most physically restorative sleep stage. During this phase:
- Growth hormone is released
- Immune repair accelerates
- Brain waste (including beta-amyloid) is cleared
- Emotional resilience is restored
Even small increases in deep sleep can have outsized effects on energy, mood, memory, and metabolic health. Many adults today are chronically deprived of deep sleep due to poor air quality, dry indoor environments, and elevated nighttime CO₂ levels—especially in closed bedrooms.
That’s where plants come in.
How a Single Houseplant Influences Sleep Biology
A bedroom plant doesn’t work through magic. It works through environmental modulation—small but meaningful changes to the air and atmosphere that your nervous system is extremely sensitive to while sleeping.
1. Improved Air Quality and Reduced VOCs
NASA’s Clean Air Study demonstrated that certain plants can remove volatile organic compounds (VOCs) from the air. VOCs are released by:
- Furniture
- Paints
- Cleaning products
- Synthetic fabrics
Even low-level VOC exposure has been linked in later studies to:
- Increased nighttime awakenings
- Reduced slow-wave sleep
- Higher sympathetic nervous system activity
By lowering VOC concentration, plants help reduce subtle physiological stress that keeps the brain from fully entering deep sleep.
2. Oxygen Balance and Carbon Dioxide Reduction
While it’s a myth that plants dramatically “oxygenate” a room overnight, some plants—particularly snake plants (Sansevieria) and orchids—continue limited oxygen exchange at night through a process called CAM photosynthesis.
More importantly, plants help stabilize CO₂ levels in poorly ventilated bedrooms. Elevated CO₂ has been shown to:
- Increase sleep fragmentation
- Reduce deep sleep duration
- Increase next-day fatigue
Lower CO₂ doesn’t just help breathing—it tells the brain that the environment is safe enough to fully shut down.
3. Increased Humidity for Better Respiratory Sleep
Indoor air is often too dry, especially in climate-controlled homes. Dry air irritates:
- Nasal passages
- Throat tissue
- Airways
This irritation increases micro-arousals during sleep—even if you don’t remember waking up.
Plants naturally release moisture through transpiration, gently increasing humidity. Studies show that maintaining indoor humidity between 40–60% is associated with:
- Fewer sleep disruptions
- Longer deep sleep cycles
- Reduced snoring and mouth breathing
One medium-sized plant can meaningfully shift humidity levels in a bedroom overnight.
4. Visual Safety Signals for the Brain
Sleep is not just chemical—it’s psychological.
Evolutionary psychology suggests that humans sleep more deeply in environments that signal:
- Life
- Stability
- Safety
Greenery provides a subconscious cue that the environment is habitable and non-threatening. Brain imaging studies show that exposure to natural elements reduces activity in the amygdala—the brain’s threat detection center.
Lower threat perception allows the nervous system to drop into parasympathetic dominance, the state required for deep sleep.
Why the Effect Can Reach 37% in Some People
Not everyone will see dramatic changes. The largest improvements tend to occur in people who:
- Sleep in poorly ventilated rooms
- Live in urban or high-pollution environments
- Have mild insomnia or light sleep
- Spend most of their day indoors
For these individuals, improving air quality and humidity can unlock deep sleep that was previously suppressed—not created from nothing.
In sleep-lab experiments where environmental stressors were reduced, researchers observed increases in slow-wave sleep ranging from 20% to nearly 40%, especially during the first two sleep cycles of the night.
That’s where the 37% figure comes from: optimal environmental correction in sleep-deprived conditions, not a universal outcome.
The Best Bedroom Plants for Sleep Support
Not all plants are equal. The most studied and effective bedroom plants include:
- Snake Plant – Nighttime oxygen exchange, low maintenance
- Peace Lily – Strong VOC absorption, humidity boost
- Aloe Vera – CAM photosynthesis, air purification
- English Ivy – Mold spore reduction, air quality improvement
One healthy plant is enough to make a measurable difference, especially in smaller bedrooms.
What a Plant Can’t Do (And Why That Matters)
A plant won’t:
- Cure insomnia on its own
- Replace good sleep hygiene
- Overcome extreme noise or light exposure
But sleep science consistently shows that small environmental improvements compound. When air quality, humidity, and psychological comfort improve together, the brain spends less energy staying alert—and more time repairing itself.
The Bigger Takeaway
The real lesson isn’t about chasing a specific percentage. It’s about understanding how sensitive human sleep is to the environment—and how modern indoor living quietly undermines it.
NASA’s research didn’t set out to improve sleep, but it revealed something essential: the air around us matters more than we think. Later sleep studies simply connected the dots.
Adding a single plant to your bedroom won’t transform your life overnight. But it can remove invisible barriers that keep your brain from sinking into its deepest, most healing rest.
And sometimes, better sleep doesn’t start with a pill or a device—but with something alive, quiet, and green, sharing the room with you while you rest.
