Can sleeping in a moldy room make you sick?

Mold growth in homes, schools, and workplaces is an increasing concern. Mold spores are very tiny and lightweight, allowing them to circulate through indoor air. When inhaled, they can cause allergic reactions, respiratory problems, and other health issues for some people. But is just sleeping in a moldy room enough to make you sick? Let’s take a closer look at the evidence.

What is Mold?

Mold is a type of fungus that grows in damp, warm environments. It produces spores as its means of reproduction. Mold spores are very tiny, usually measuring 2 to 10 micrometers in size. For reference, a single human hair is about 60 to 120 micrometers wide. This means you cannot see individual mold spores without a microscope.

There are thousands of species of mold. Some of the most common indoor molds include Cladosporium, Penicillium, Alternaria, and Aspergillus. Stachybotrys chartarum, also known as “black mold,” is less common but gains a lot of media attention due to its toxic properties.

Mold grows best in damp conditions, when moisture levels exceed about 40%. Materials like carpet, wallboard, wallpaper, wood, and insulation provide good environments for mold if they become and remain damp for over 24 to 48 hours. Bathrooms, basements, kitchens, and areas with water damage are common sites for mold growth. Mold can begin forming within 24 to 48 hours of the onset of proper conditions.

How Mold Enters and Circulates Indoors

Mold spores begin circulating through the indoor air when they are released from mold colonies. Activities that disturb mold growth can cause higher levels of spores to be released. Some examples include:

– Opening boxes containing moldy materials
– Pulling up old moist carpets
– Knocking down moldy drywall

Mold spores can also get indoors through open windows and doors, ventilation systems, and on people, pets, and objects coming in from outside. Mold spores begin circulating through the indoor air when they are released from mold colonies. Activities that disturb mold growth can cause higher levels of spores to be released. Some examples include:

– Opening boxes containing moldy materials
– Pulling up old moist carpets
– Knocking down moldy drywall

Mold spores can remain airborne for extended periods until they land on a damp surface and begin growing again.

Health Effects of Mold

Inhaling mold spores can cause allergy symptoms, trigger asthma episodes, or lead to other respiratory problems in some people. Mold spores contain allergens and irritants. Reactions depend on the type and amount of mold exposure as well as the sensitivity of the individual. Potential health effects include:

– Runny nose, eye irritation, cough, congestion, sore throat
– Wheezing, difficulty breathing
– Asthma attacks
– Hypersensitivity pneumonitis (inflammation of lungs due to immune system reaction)

More severe reactions are primarily seen in people with chronic illnesses or mold allergies. Toxic molds like Stachybotrys can cause severe symptoms and serious health effects through mycotoxin production though this is very rare. Mycotoxins are hazardous substances that mold produces under certain environmental conditions.

Evidence also suggests links between mold exposure and development of asthma in previously healthy individuals. Mold may also trigger asthma attacks in people with asthma who were previously unaffected by molds.

Some people may have no reaction at all to mold spores while others are profoundly affected. Genetics, age, underlying health conditions, and concurrent exposures are all factors that influence individual responses.

Is Sleeping in a Moldy Room Enough to Make You Sick?

There are currently no standardized thresholds for “safe” or “unsafe” levels of indoor mold growth. Whether or not an individual will get sick from sleeping in a moldy room depends on the type and extent of mold present as well as their personal sensitivity.

Here are some key considerations when evaluating potential risks of sleeping in a moldy room:

– Amount of visible mold growth – More extensive mold is more likely to cause problems. Look for signs of moisture damage and visible mold growth on surfaces like walls, ceilings, carpets, etc.

– Mold type – Some molds like Stachybotrys are more hazardous than common varietals when present in high concentrations. It is impossible to identify species without testing.

– Mold allergies – People with allergies or asthma are most at risk for adverse reactions from mold exposure. Pre-existing respiratory conditions increase vulnerability.

– Individual susceptibility – Age, genetics, occupational exposures, and current health status all play a role in individual responses. Some people get sick more easily from mold than others when exposed to the same environment.

– Duration and frequency of exposure – Longer, more frequent exposure provides a greater opportunity for adverse effects. Staying for a short time in a mildly moldy room is less risky than sleeping there regularly.

– Other indoor air contaminants – Multiple chemical and biological contaminants often co-occur with mold. Their combined effects may be more detrimental.

While brief or limited exposure to mildly moldy conditions is unlikely to cause illness in most healthy individuals, regular exposure or high levels of indoor mold increase the risks. Severe reactions are more likely in susceptible individuals or those with mold allergies.

Let’s explore this question in greater depth by reviewing some relevant scientific studies and reports.

Scientific Research on Health Effects of Indoor Mold Exposure

Numerous studies have found links between indoor mold exposure and adverse respiratory health effects including worsening of asthma symptoms. Here is a review of some key scientific literature:

World Health Organization Guidelines

In 2009, the World Health Organization (WHO) issued guidelines on indoor air quality, dampness, and mold. Their report concluded:

– There is sufficient evidence linking indoor exposure to mold and dampness to health effects like asthma development and exacerbation, cough, wheeze, and upper respiratory tract symptoms.

– The presence of mold or dampness indoors is associated with increased likelihood of adverse respiratory health effects like asthma, chronic bronchitis, allergic rhinitis, dyspnea, and respiratory infections.

Meta-Analysis in Clinical & Experimental Allergy

A 2018 meta-analysis published in Clinical & Experimental Allergy reviewed 33 studies on indoor mold exposure and asthma development. The authors concluded:

– Exposure to indoor mold was associated with a 30% to 50% increase in asthma development.

– The evidence indicates indoor mold exposure is a risk factor for developing asthma in both children and adults.

Study in Current Opinion in Allergy and Clinical Immunology

A 2019 literature review in Current Opinion in Allergy and Clinical Immunology evaluated evidence linking mold exposure to worsened asthma symptoms in those with existing asthma. The study concluded:

– Multiple well-designed studies show indoor mold exposure significantly exacerbates asthma symptoms including wheezing, cough, and shortness of breath.

– Mold sensitization is also associated with worse pulmonary function and more frequent healthcare utilization in asthmatics.

Study in Annals of Agricultural and Environmental Medicine

A 2012 study in Annals of Agricultural and Environmental Medicine assessed airborne mold concentrations and asthma severity in different indoor environments. They found:

– Highest concentrations of total mold spores and multiple allergenic types were in moisture-damaged homes.

– Children living in those homes had significantly worse asthma symptoms and severity scores compared to children in reference homes.

Study in Journal of Asthma

Researchers in this 2004 study exposed asthmatic adults to high versus low levels of Aspergillus fumigatus mold for 2 hours. The results showed:

– Higher exposures led to significantly greater decreases in lung function as measured by FEV1 and FVC.

– Asthmatics are susceptible to lung function impacts following relatively brief exposures to increased mold.

Overall, there is substantial evidence indicating indoor mold exposure can initiate asthma and exacerbate existing cases. Even low to moderate levels have been linked to respiratory effects in sensitive individuals. Let’s examine some possible mechanisms behind these associations.

How Indoor Mold Exposure Can Lead to Adverse Health Effects

Several biological mechanisms may explain how inhaling indoor mold spores harms respiratory health:

Allergic reactions – In sensitized individuals, inhaled mold spores trigger IgE antibody production and histamine release leading to inflammation, airway constriction, coughing, and breathing difficulties typical of allergic responses.

Inflammatory reactions – Mold spores and fragments contain irritants like β-glucans and mycotoxins that damage airway epithelial cells. This stimulates an inflammatory response involving immune cells like neutrophils and cytokines that impair breathing.

Infections – Some molds like Aspergillus are opportunistic human pathogens, occasionally causing serious fungal infections in immunocompromised people. Inhalation is the primary route of exposure.

Toxicity – Mold species like Stachybotrys chartarum generate hazardous mycotoxins under certain conditions that can damage airways and lungs through oxidative stress, cytotoxicity, and other mechanisms when inhaled.

Frequent and cumulative exposures to indoor molds through normal breathing during sleep could plausibly lead to sufficient spore inhalation for these effects in vulnerable individuals. Let’s look now at some documented cases of illness linked to sleeping in moldy rooms.

Case Reports: Sickness Associated with Sleeping in Moldy Rooms

While controlled studies provide the strongest evidence, case reports also shed light on the question of whether sleeping in moldy indoor environments causes illness. Here are a few examples:

Allergic Fungal Sinusitis

A case study in the Journal of Allergy and Clinical Immunology described severe allergic fungal sinusitis in a 9 year old boy. His bedroom had water damage and mold growth due to leaks. Sinus cultures grew multiple fungal species. Avoiding his bedroom led to symptom improvement.

Hypersensitivity Pneumonitis

A report in Archives of Environmental Health presented a married couple with chronic coughs, fatigue, breathing problems, and low grade fevers after moving into a water-damaged home. Mold growth was extensive. The author concluded they developed hypersensitivity pneumonitis from indoor mold exposure.

Asthma and Rhinitis

A case study in Pediatric Asthma, Allergy & Immunology followed five children with respiratory problems and allergy symptoms only during occupancy in a moldy water-damaged home. All improved after remediation or moving out.

Fungal Exposure and Health Impacts

While not proof of causation, these and other case reports do indicate an association between occupying moldy rooms, especially for sleeping, and development of respiratory illnesses in susceptible individuals. However, brief or limited exposures are unlikely to affect most healthy people. Let’s look now at some steps you can take to assess potential risks in your own living environment.

How To Check Your Bedroom For Mold Problems

It’s important to note that visible mold growth is only the tip of the iceberg. Mold can hide unseen behind wall boards, under carpets, above ceiling tiles, and elsewhere. To thoroughly evaluate your sleeping environment for mold risks, here are some steps to take:

Inspect visually – Carefully examine all surfaces for signs of moisture damage and mold growth. Look along baseboards, corners, walls, and ceilings. Don’t forget to move furniture and look under carpets and pads.

Check for musty odors – Use your nose to detect telltale moldy or stale smells. Don’t just scent the air, press your nose directly onto carpet and other materials.

Monitor humidity – Use a hygrometer to measure humidity levels in your bedroom. Maintain relative humidity under 50% to control mold growth. Consider using a dehumidifier if levels exceed this threshold.

Look for water damage – Inspect under sinks, near plumbing fixtures, and along baseboards for signs of water intrusion like staining or warped surfaces. This can provide mold growth sites.

Get samples tested – Hire a professional to take surface, air or dust samples to test for mold species present and spore levels. This provides definitive proof of a problem.

Consider an inspection – A qualified industrial hygienist can perform a thorough mold investigation and advise you on any hazards present, particularly if you are susceptible to mold issues.

Checking your sleeping space thoroughly using these guidelines can help uncover any dampness issues or mold growth. Take further steps like cleaning or remediation if problems are found. Let’s go over effective ways to eliminate mold from your bedroom.

How To Remove Mold from Your Bedroom

If you discover a mold issue, you’ll want to take prompt action to fix it. Here are best practices for mold removal:

Correct moisture sources – The first priority is addressing whatever is allowing mold to grow like leaks or high humidity. Mold cannot be permanently removed unless the damp conditions supporting growth are fixed.

Protect yourself – When cleaning mold, use an N95 respirator mask, goggles, and gloves to limit spore exposure. People with mold allergies may need extra precautions. Open windows and use fans for ventilation.

Clean surfaces – Follow remediation guidelines to clean mold off nonporous surfaces like tile, metal, glass, plastic, etc. Use detergent, commercial mold removers, bleach, or other disinfectants.

Remove & replace porous materials – Moldy porous materials like drywall, carpeting, insulation, and ceiling tiles cannot be adequately cleaned once contaminated. Remove and replace them.

Use HEPA filtration – Run HEPA air scrubbers while working and a dehumidifier afterwards to clear spores and lower humidity. This helps prevent mold from recurring.

Hire pros if needed – For large mold problems or in HVAC systems, hire professional mold remediators for full containment, cleanup, and decontamination.

Maintain low humidity – Going forward, continue monitoring bedroom humidity and take steps like running a dehumidifier or improving ventilation if needed to keep levels below 50% to discourage mold growth.

With diligent inspection, prompt remediation, moisture control, and regular maintenance, you can keep your bedroom free from mold hazards. Let’s summarize the key points we’ve discussed so far.


Research clearly shows indoor mold exposure can lead to adverse respiratory effects, especially in those with allergies or other vulnerabilities. While limited exposure is unlikely to significantly impact most healthy people, regularly inhaling mold spores while sleeping could plausibly impair breathing enough to cause illness in some. There are documented cases of this occurring when bedrooms have dampness and mold growth issues.

The best course of action is inspecting carefully for signs of moisture or mold and promptly fixing any issues found. Limiting mold growth by controlling humidity and maintaining good indoor air quality will also help minimize risks. While a modest amount of mold in your home is normal and often harmless, it’s smart to identify and resolve dampness problems before they create unhealthy conditions. With reasonable precautions, sleeping in moldy rooms is a hazard that can be avoided.

Leave a Comment