Natural Latex Foam vs. Synthetic/Polyurethane Foam -- What's the difference?

We received a phone call recently from a gentleman who was frustrated with his latex research.  I informed him that “There’s natural latex, and then there’s synthetic latex.”  His reply was, “Well, but latex is latex is latex, right?”     

The answer is Absolutely not.  As a matter of fact, there is a world of difference between natural latex and synthetic/polyurethane foam.  To make things even more interesting and/or confusing, there are different variations of both kinds.

Natural latex is manufactured from sap tapped from rubber trees, then it is either vulcanized (Dunlop method) or frozen, then vulcanized (Talalay method.)  I don't want to get too involved in which method is better, because it's hugely dependent upon the processing facility and a number of other factors.

The point is, natural latex is an incredibly resilient and durable, clean and supportive material.  It is resistant to dust mites, anti-microbial, antifungal, and hypo-allergenic.

The important thing to remember when considering a product made of natural latex is purity - what is the percentage of pure natural latex vs fillers or synthetic material.  Look for certification by an independent laboratory such as Oeko-Tex, which tests for chemicals and toxins in the finished product.  The Oeko-Tex stamp of approval will attest to the cleanliness and purity of the product.

Some manufacturers add fillers (most commonly clays, calcium oxide, or titanium dioxide) to the natural latex to make it go further (imagine taking one gallon of milk and diluting it with water to create two gallons of milk).  While the finished product will be less expensive, the addition of fillers ultimately makes the latex less durable and more apt to rapid breakdown.  Here’s where the consumer needs to be very vigilant…the fact is that natural latex with additives such as those listed above can technically still be called “natural latex”.

Synthetic latex (aka polyurethane foam/memory foam) is made of petroleum by-products, sometimes actually mixed with natural latex.

Again, that's where you have to be really careful.  There are many manufacturers who tout their product as “natural latex”, when in fact it's actually a blend of natural AND synthetic. Interestingly, Dunlop and Talalay latex can be either natural or synthetic.  Needless to say, Caveat emptor -- do your research!

Synthetic latex, being chemically based, has a tendency to break down quicker than natural latex.  If you have ever had a warranty issue with a mattress, you know what I mean.  Have you ever had a body impression in your mattress measured by your friendly local mattress salesman and told that it's “normal wear and tear?”

Polyurethane foam /synthetic latex are actually graded on how quickly they're expected to break down.  That's the reason you have to wait until the body impression is at least 1.5 inches (in most cases) in depth to get your warranty to kick in.

Synthetic latex / polyurethanes also have a tendency to off-gas.  That is, the chemicals inside the mattress will escape and cause a strange odor.  Guess what? You're breathing those chemicals in while your skin is absorbing them.  There's also an issue with synthetics being unable to absorb and release moisture properly, trapping moisture and heat, which is a great breeding ground for molds, mildews, dust mites and other undesirable little critters.

What does that mean for you?  Well, it means that the mattress made with poly-foam or synthetic latex is less durable: compacting or developing body impressions when confronted with weight and moisture (by the way, the human body emits about 1 liter of body moisture while sleeping, not necessarily sweat, just moisture being released by the body.  No kidding… yuck!!!) 

Take this into consideration also: the average queen-sized polyurethane foam mattress covered in polyester fabric loses HALF its weight over ten years of use. Where does the weight go?

Polyurethane foam oxidizes, creates “fluff” (dust) which is released into the air and eventually settles in and around your home as well as in your lungs.  Yes, you breathe in this dust.  And some of the chemicals used in these types of mattresses include formaldehyde, styrene, toluene di-isocyanate (TDI), antimony...the list goes on and on.  Once again, do your research if you're concerned about these things.  We suggest reading up on the effects of chemicals on www.epa.gov. 

The bottom line:  Natural latex (without fillers) is more resilient/durable, cleaner/healthier and more comfortable -- anti-microbial, anti-fungal,and hypo-allergenic, as well as being dust mite resistant and biodegradable.  You'll pay a bit more for anything made of pure natural latex, because it's more expensive to obtain and produce, but you get your money’s worth out of the product in longevity and comfort.

When purchasing a natural latex bed, remember grandmother’s excellent advice:  “If it seems too good to be true, it probably is.”  A natural latex bed free of fillers won’t be inexpensive.  Find out what warranty corresponds to the item you’re interested in, and read it!  The warranty will tell you a great deal.  Also, keep in mind that websites can be tricky: many that have the Oeko Tex logo do have natural latex products, but also polyurethane.  

And there you have it, a crash-course in latex foam.  Hope that helps you navigate the mattress world.  Good luck & happy shopping! 

Get Some Sleep: Are you a night owl? Here's why

I hear the floorboards creak, the toilet flush, first one shoe drop to the floor, then the other.  My husband pulls back the covers and climbs into bed, disturbing the dog, who now spins around rattling her tags looking for a new, cozy den.  I groan and turn over to look at the clock:  3 a.m., an early night for him.  You see, my husband is what many people call a "night owl," but really he suffers from a circadian rhythm sleep disorder called delayed sleep phase disorder.

Circadian rhythm means a 24-hour cycle.  Humans have a 24-hour sleep/wake cycle that is linked to the 24-hour cycle of the sun.  So, in the optimal situation, we rise in the morning and after about 16 hours of wakefulness we are sleepy and we go to bed and sleep for eight hours.  In my last blog, I talked about shift work disorderand how shift workers are not able, because of their jobs, to flow with this natural rhythm.

People with delayed sleep phase disorder also get out of sync with what we would consider normal bed times (10 p.m. to midnight), but for unknown reasons. The exact prevalence in the general population is unknown, but it is estimated to affect 7 percent to 16 percent of teens and young adults.

Delayed sleep phase disorder usually begins in adolescence or early adulthood.  Sleep onset is delayed at least two hours from social norms, and these altered sleep/wake times can impair the work, academic and social parts of sufferers' lives.

People with DSPD often complain of insomnia because they try to go to sleep at a normal time but their internal rhythm is set to a later time and sleep is usually impossible until very late.  Then, if they have to get up for work or school, they are very tired and sleepy in the daytime and are not functioning at their highest capabilities. Often, they will steal a nap, but that only sets them up for further delay in their bedtime.

Usually the patients who show up at the sleep center are teens who are brought in by their mothers because they can't get up and make it to their early morning classes.  Their grades are failing and the school is threatening to expel them.  How do I help them?  Well, I must return to my near-constant theme:  Light.

We get them on a schedule where we slowly move up their bedtimes - just 15-30 minutes each time over a series of weeks. With each change in bedtime, they are instructed to be sure to avoid bright light two hours before the desired bedtime.  We often need to use glasses that filter the blue light because it is not realistic to think that teenagers are not going to be on the computer or using some electronic device. 

I also have them get outside and get some bright light in the mornings.  Where I am in Chicago, for much of the year we recommend that such patients use light boxes in the morning. I recommend the ones made by Lite Book because they use LED technology, which means they are smaller and patients  need to spend only 15-30 minutes in front of the unit.

We also use melatonin, but not as a sleep aid.  Instead, we use it to alter people's circadian rhythm, and therefore, we give it 5-7 hours before desired bedtime and we use small doses (0.5-1.0 mg).  And I always recommend that they try this at home the first few times in case it makes them sleepy right away.

I would like to caution that although this general principle of bright light in the morning and dim light before bedtime is easy enough to understand, it is also easy to apply the principle incorrectly and actually make matters worse.  For example, a well-meaning mother of a 16-year-old reads this and tomorrow morning hauls her son out of bed at 6:30 a.m. to get him to his first AP class.  The next night, to her dismay, he stays up even later, and getting him up the following morning would require inviting the marching band to hold practice in his bedroom.

What has gone wrong?  Well, when mom got him up at 6:30 a.m., he had only had 4½ hours of sleep and his core body temperature had not reached its low point.  When his eyes received bright light before the lowest drop in core body temperature, then the internal clock in the brain was being reset to a later time and actually delaying the sleep onset for the next night. Many times we have to wait until a vacation to try to reset someone's clock.  Most times, the help of a sleep physician is essential, and always, the patients themselves have to want to change their schedule.

Another word of caution: It is easy to confuse this disorder with insomnia, but just giving the young person a sleeping pill doesn't usually work to reset the internal clock.

Why do some teens have these dramatic shifts in sleep onset and not others?  This can run in families and changes in one of the circadian clock genes have been associated with this disorder but we cannot yet point to a specific genetic mutation that causes this problem. Delayed sleep phase can be associated with depressive symptoms but the good news is:  Many will naturally outgrow it, especially when the responsibilities of adult life force them into becoming morning people.  Some, like my husband, will return to their nocturnal ways every chance they get.

Lisa Shives, M.D., is the founder of Northshore Sleep Medicine in Evanston, Illinois. She’ll blog on Tuesdays on The Chart. Read more from her at Dr. Lisa Shives’ Sleep Better Blog.

The information contained on this page does not and is not intended to convey medical advice. CNN is not responsible for any actions or inaction on your part based on the information that is presented here. Please consult a physician or medical professional for personal medical advice or treatment.

Post by: Lisa Shives M.D. - sleep expert Filed under: Sleep