WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
By Dr. Mercola
How long have you been sleeping on your pillow? If you can't remember, it's probably been too long… the average person keeps their pillow for more than three years, and more than half only replace their pillow and bedding when they notice it starts wearing out.1
But should you replace your pillow much sooner? The Sleep to Live Institute in America recommends replacing your pillow every six months, which might be a bit aggressive (and the Institute has ties to the industry).
A more reasonable approach may be to use the folding test: fold your pillow in half, and if it stays folded instead of springing back into shape, it's time to find a new one. If you prefer to use length of time as a gauge, the Sleep Council in the UK recommends replacing pillows every two years.2
Neck Problems and Dust Mites: Risks of Keeping Your Pillow Too Long
To avoid neck pain, your pillow should, ideally, fill the gap between your head and shoulders when you lie down.3 If you keep your pillow too long, it will flatten out, leaving your head and neck without adequate support night after night, and this could lead to pain and restless nights.
The other significant issue with keeping a pillow too long is a dust-mite infestation. Dust mites are microscopic bugs that feed on dead skin cells and thrive in warm, humid environments… like your pillow. Dust mites don't bite and they don't spread diseases, but they are the most common allergen found in household dust.
It's estimated that about 10 percent of Americans are allergic to dust mites (or, more specifically, to their fecal pellets and body fragments). In those allergic, dust mites can trigger allergic symptoms and high levels of exposure have been linked to the development of asthma in children.4
Down pillows and comforters are known to attract the most dust mites, and they are difficult to clean properly in order to remove them. However, any pillow can become a dust-mite reservoir and, in fact, after one year of use, 10 percent to 15 percent of your pillow's weight may be made up of dust-mite waste…5
If you find that your allergy symptoms are worse in the morning, it could very well be due to high levels of dust mites in your pillow and bedding. Washing your pillow once a week in hot water (130-140 degrees F) will kill dust mites (and so will freezing it overnight), so it's a good idea to use these preventive strategies if you have a dust-mite allergy.
You'll need to wash (or freeze) the whole pillow (not just the pillow case). You can also encase your pillows in a dust-proof cover, or choose a high-quality wool pillow, which will be hypoallergenic and will repel dust mites naturally. Wool pillows are naturally fire resistant and are free from dangerous flame retardants.
Your Pillow Might Contain a Million Fungal Spores
What else might be lurking in your pillow? Fungal spores, including Aspergillus fumigatus, which can cause Aspergillosis, an infection that begins in your lungs and may spread to other parts of your body, such as your brain.
When researchers tested samples of pillows, which had been used anywhere from 1.5 to 20 years, they found several thousand spores of fungus per gram of pillow, which means any one pillow could contain more than 1 million spores.6
Up to 16 different species of fungus, from varieties found in bread to varieties common in showers, were detected in the individual samples. Pillows made from synthetic materials tended to have higher levels, which is another reason why pillows made from natural wool are preferable.
According to one of the study's researchers, since you spend so much time in close proximity to your pillow, fungal contamination could have health implications:7
"We know that pillows are inhabited by the house dust mite which eats fungi, and one theory is that the fungi are in turn using the house dust mites' feces as a major source of nitrogen and nutrition (along with human skin scales). There could therefore be a 'miniature ecosystem' at work inside our pillows.
…Since patients spend a third of their life sleeping and breathing close to a potentially large and varied source of fungi, these findings certainly have important implications for patients with respiratory disease - especially asthma and sinusitis."
Your Pillow Could Be a Key Source of Exposure to Flame-Retardant Chemicals
The risks of exposure to dust mites and fungal spores pale in comparison to those of flame-retardant chemicals that are added to some sleeping pillows. Using an x-ray analyzer that can detect bromine levels in household items, researchers were able to estimate how much of one type of flame-retardant chemical – polybrominated diphenyl ethers (PBDEs) – they may contain.
Sleeping pillows topped the list (followed closely by vehicle sleep cushions). PBDEs resemble the molecular structure of PCBs, which have been linked to cancer, reproductive problems, and impaired fetal brain development.
Like PCBs, even though certain PBDEs have been banned in some U.S. states and the European Union, they persist in the environment and accumulate in your body – and often exist in products imported from other countries.
Higher exposures to PBDEs have been linked to decreased fertility, 8 which could be in part because the chemicals may mimic and therefore disrupt your thyroid hormones. Research has suggested PBDEs can lead to decreases in TSH (thyroid-stimulating hormone),9 which is typically a sign that your thyroid is being disrupted and you are developing hyperthyroidism.
This can have significant ramifications both for you and your unborn child if you're pregnant. As for cancer, one type of PBDE (decaBDE) is classified as a possible human carcinogen by the US Environmental Protection Agency (EPA), while the others remain largely untested.
A study by researchers at the University of California, Berkeley also revealed that both in utero and childhood PBDE exposures were associated with neurodevelopmental delays, including decreased attention, fine motor coordination, and cognition in school-age children.10
During the pillow study, researchers found that bromine levels in sleeping pillows were significantly associated with PBDE levels in study participants' blood.11 Certain types of pillows were worse than others, with polyurethane foam pillows topping the list of worst offenders by a large margin:12
- Polyurethane foam pillows (3,646 parts per million)
- Polyester fiber pillows (107 parts per million)
- Feather pillows (6 parts per million)
Exposing yourself to flame-retardant chemicals while you sleep is a completely unnecessary risk, since natural pillows are available that contain no such chemicals. High-quality wool pillows (and bedding and mattresses) are naturally flame resistant, which is why no flame retardants like PBDEs are used.
Is Your Pillow Right for Your Sleep Position?
More than 90 percent of Americans say that having a comfortable pillow is important to getting a good night's sleep,13 but what constitutes "comfortable"? You probably have a preference for a firm or fluffy pillow, and you might even stack up two or more. If you wake up pain-free and feeling well rested, your pillow situation is probably fine… but if, on the other hand, you're waking up with back and neck pain, or struggling with snoring or acid reflux, adjusting your sleep position, including your pillow, may help.
It's generally accepted that the best sleep position is on your back. When you sleep on your back your head, neck, and spine maintain a neutral position, and acid reflux symptoms are minimized (because your face is not pushed up against a pillow, back sleeping may also be best for preventing facial wrinkles).When sleeping on your back, no pillow is actually best for your spine, but a fluffy pillow that keeps your head supported while still being relatively thin will also work. If you use a thick pillow you'll lose out on some of the benefit of back sleeping, as this will push your head and neck forward, impacting your breathing.
Side sleeping allows your spine to stay in a fairly neutral position while helping to reduce snoring issues, if present, in some people. If you sleep on your side, look for a firm pillow to fill the gap between your ear and outside shoulder. Some people also find that sleeping on their side with a pillow between their knees radically improves low back pain, as it tends to normalize the normal spinal curves. As for stomach sleeping, it's generally regarded as the worst position of all because of the way it distorts the natural curve of your lower spine. If you choose to sleep on your stomach, look for a thin pillow (or skip the pillow entirely).
You may want to put a pillow under your stomach to help alleviate potential back pain from this sleeping in this position. Keep in mind that you needn't have only one type of pillow. You might have a firm pillow to support your head while reading in bed and another that you prefer for sleep. The thickness and firmness of your pillow is up to your personal preference, but the material it's made out of should be natural, not synthetic, to avoid exposure to flame-retardant chemicals.
Finally, you'll want to be sure your pillow is washable to reduce dust mites and other organisms, like fungal spores. Natural pillows will be easily washable, but many synthetic foam pillows are not. In fact, the porous foam cells in foam pillows may hold onto water if you try to wash them, which could facilitate the growth of fungus. I personally would never sleep on anything other than a wool pillow for health reasons.