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Control Relative Humidity for Better Sleep

Slaine M. Logan hails from the state of North Carolina. She has long been an avid researcher, product reviewer, and health fanatic.

Long-term exposure to excessive humidity in your home can encourage the growth of allergens such as various species of mold.

Long-term exposure to excessive humidity in your home can encourage the growth of allergens such as various species of mold.

Allergies and Sleep

The relative humidity of our surroundings plays a crucial role in our comfort in more ways than we usually think about. We notice the stickiness accumulating on our skin if we are outside on a hot, muggy day, or if we are inside a residence where air conditioning is not being utilized. Some may also get nosebleeds during cold weather when the air is too dry. If the humidity is extremely high in our bedrooms, the discomfort may also make it difficult to sleep.

But relative humidity can have a more long-term effect on our ability to get a good night's slumber. Humidity levels play a role in the development or the prevention of allergens and allergic conditions, and can also exacerbate or relieve symptoms. Keeping the humidity levels in our home and bedrooms at an ideal range has considerable health benefits, among which is improved sleeping conditions.

Dust Mites

Dust mites are invisible to the naked human eye, being only 1/4 to 1/3 of one millimeter long. However, for bugs that are so tiny, they can cause a considerable influence in the household to someone that is allergic.

Dust mites actually consist of several species. There are four that are the most common:

  • European house dust mite
  • American house dust mite
  • Mayne’s house dust mite
  • Dermatophagoides microceras

The average person sheds about 1.5 grams of skin per day, and given the fact that you spend 1/4 to 1/3 of your day in bed, your sheets are going to accumulate a significant portion of it. Dust mites feed on the dead and decaying organic matter of humans and pets.

There is a side effect to all this feeding. Dust mites, like any other animal that feeds, produce waste products. Though each mite has a lifespan of only between two to ten weeks, they can produce up to several thousand total waste deposits, between their fecal particles and enzyme particles. For many people, this will cause no hardship. However, there are others whose immune systems misidentify these waste deposits as troublesome invaders, and begins to react by producing antibodies.

Temperature and Humidity Control for Dust Mites

One unfortunate component of this problem is that dust mites are most comfortable and thrive best in the same temperature range that humans tend to prefer indoors – 68 to 77 degrees Fahrenheit. So, unless you have unusual temperature preferences, that is one obstacle to keeping the dust mite population in your bedroom down.

Humidity, however, is another matter. Dust mites prefer humidity levels of over 70 percent, and cannot thrive at levels below 50 percent. Most people, on the other hand, are comfortable with the relative humidity in their bedroom below that level.

Dust mite control is analogous to mosquito control in that it is not possible to repel every last one of them. It is about reducing their presence, as these microscopic bugs burrow deep within a mattress, as well as other fabrics in the bedroom. Remember, it is not the mites that some people are actually allergic to, but their waste deposits. If most of them are kept away from surfaces, and instead are burrowed within a mattress, the allergic person will have far less exposure to them and their waste. If you are one of these people, keep your bedroom – as well as the rest of the house, at a relative humidity of less than 50 percent.

Central air conditioning units keep down excess humidity and are a reliable way to control temperature. They also trap allergens in the filter, and enable you to keep your home cool without opening your windows and exposing you to allergens.

Central air conditioning units keep down excess humidity and are a reliable way to control temperature. They also trap allergens in the filter, and enable you to keep your home cool without opening your windows and exposing you to allergens.


A bedroom or house with high humidity is bound to spawn more than an overpopulation of dust mites. It also presents a friendly environment for several types of mold to grow. If you have not been formally tested by an allergist for mold, one good indication that it is the culprit of your reactions is that the symptoms make themselves present over more than one season. When an allergic person inhales the spores of the mold, symptoms can onset quickly, but can also be delayed. Symptoms of mold allergies include

  • Sneezing
  • Runny nose
  • Congestion
  • Postnasal drip
  • Eye irritation

It is no surprise that the first place indoor molds often are spotted are places such as basements and bathrooms. The most common types of household molds are

  • Penicillium
  • Cladosporium
  • Aspergillus
  • Alternaria

In addition, there is a somewhat less common but more hazardous mold you need to watch for. With the scientific name of stachybotrys, it is more widely known through its common name – black mold. You do not need to be allergic to mold to be affected by its presence. Its spores contain mycotoxins that can lead to breathing difficulties. And in rarer cases, complications such as

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  • Memory loss
  • Hearing loss
  • Flu-like symptoms
  • Dizziness

This particular mold requires an exceptionally moist environment. A house with high overall humidity will commonly be the most vulnerable.


What most people call eczema is actually a group of conditions that cause considerable itching, irritation, and rash effects. If the symptoms are severe enough, it can inhibit your ability to fall asleep at night. Some conditions under the umbrella of eczema are allergy related, though the cause can also be environmental. With a chronic condition approximately three percent of adults and children, eczema can be exacerbated by air that is too dry. This aggravation can often happen to the point where the sufferer is unable to sleep due to the constant severe itch.


There is a reason that incidences of irritated nasal passages and sinuses rise during the colder months. Cooler air can hold less moisture, and excessive dryness can dry out and irritate the lining of those passages and mucous membranes. These conditions are irritating enough for people with normally functioning respiratory systems. Imagine what this is like for those who already suffer from a preexisting condition such as asthma.

Cold and Flu Viruses

The annual cold and flu viruses also peak during the coldest months of the year. In addition to the drier air rendering the nasal passages more vulnerable to permeation from the viruses, a dry environment allows them to survive for a longer period of time on surfaces, thus increasing their chances of spreading. The congestion, coughing, and overall discomfort resulting from the subsequent conditions can make it more difficult to sleep.

Ideal Relative Humidity

The ideal relative humidity indoors should be anywhere from 40 to 50 percent. In addition to minimizing the manifestations of allergens at both ends of the spectrum, that is also generally the most comfortable levels for humans and many pets.

A portable dehumidifier. If your air conditioning unit is broken, or you do not have one, these can help ease the burden in humid weather. They also work extremely well for basements.

A portable dehumidifier. If your air conditioning unit is broken, or you do not have one, these can help ease the burden in humid weather. They also work extremely well for basements.

Control Humidity During the Warm Months With Air Conditioning

The vast majority of the homes in the United States have air conditioning capabilities. Without a doubt, this is the most effective way of controlling your indoor relative humidity in the warmer months. It is true that several large, running fans can provide some comfort in establishing a breeze of circulated air. However, while the breeze may make you feel somewhat cooler, if the air that is being circulated is hot and damp, it will not solve the problem of excess indoor humidity.

The most effective system of air conditioning for the complete home is a central air unit. It has several advantages over the individual window unit.

  • Less noise
  • Uniform temperature control throughout the house
  • It will cool a large area relatively more efficiently
  • For most homes, the working components are outdoors. Some exceptions are apartment style condominiums.

In addition, the central air unit has a filter to trap dust and other allergens such as dead skin, dander, and pollen brought in from the outside. A central air conditioner would be the ideal option for most homes.

However, if a working central air system is not in your budget, or if you have a very old home that is not set up for it, window units also have their advantages.

  • Cost. This is true for the unit itself, as well as for running
  • Energy efficiency
  • Can be easily moved from room to room, or to another home

A window unit, or two, may be a better option for exceptionally small homes, offices, and especially those living in a single room space, such as a college student in a dorm. When I was in college, my time in the dorm room studying and sleeping was made much more pleasant by a Frigidaire 5,000 BTU window unit, which also has a remote control.

Humidifiers and Dehumidifiers

An air humidifier can do wonders to the allergy sensitive in dry conditions. Whether it is a by-product of your heater, or you live in an arid environment such as Arizona, this can be a big relief for allergies related to dry air. If you have a cold or flu, it will also significantly aid in reducing some of the symptoms that can prevent adequate sleep for recovery. There are both whole house and individual room humidifiers, depending on your needs. I do not have low humidity related allergies, but anytime I have come down with congestion, the Ultrasonic Cool Mist Humidifier has done a first-class job in providing me with some relief without fail since I purchased it. It also runs relatively quietly.

By contrast, dehumidifiers are effective tools for those muggy days if you do not have air conditioning, or it has malfunctioned, or for high humidity days with more moderate temperatures. They are also a great device to use in your basement, where it can be cool but damp. My Ivation 70 Pint Energy Star Dehumidifier helps keep my finished basement a pleasant atmosphere to entertain guests. It is well-priced for its capacity and performance, and my relative humidity gauge consistently stays in the range of 44-47 percent.



This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

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