DEV Community: Jacob Katz

Six natural fibers ranked by dust-mite resistance mechanisms

Jacob Katz — Mon, 31 Aug 2026 10:30:25 +0000

Why comparing natural fills is harder than it looks

No natural fiber eliminates dust mites. The EPA and AAAAI both rank allergen-barrier encasements and hot-water washing first, not material choice. But some fills have defensible structural or chemical properties that create a less hospitable microclimate for colonization.

The problem is that most pillow fill comparisons skip the mechanism entirely. A claim like "resists dust mites" carries no test method, no measurement, and no falsifiable threshold. What follows is a ranking of six natural fills by how well their resistance case holds up when you ask for the data.

The temperature threshold backed by a 1992 study

A 1992 peer-reviewed study found that water temperature around 130°F (54°C) kills dust mites far more effectively than cold or warm water. That temperature became the threshold in EPA guidance for washing bedding weekly.

This matters because most natural pillow fills cannot be machine washed at any temperature. Wool, shredded Dunlop latex, kapok, cotton batting, and buckwheat hulls all require spot cleaning or never washing at all. The defense moves to the cover and a separate waterproof protector, both of which can reach 130°F in a standard residential washer.

Fill type	Washable at 130°F	Mechanism type	Evidence strength
Organic wool	No (cover only)	Chemical + structural	Third-party endorsed
Shredded Dunlop latex	No (spot clean)	Structural inference	Untested
Buckwheat	No (cover only)	Structural inference	Untested
Kapok	No (never wash)	Chemical property	Untested
Cotton batting	No (cover only)	Washability only	Method-based

Organic wool stacks three independent properties

Organic wool has the strongest case of the six fills because it combines three mechanisms:

Lanolin's fatty acids coat shed skin flakes and are toxic to mites
Moisture wicking holds the microclimate below the roughly 50% relative humidity mites need to reproduce
Keratin scales physically block mites from burrowing into the fiber surface

Allergy UK has endorsed wool bedding for allergy sufferers, the only third-party validation of a natural fill in this comparison. A PMC-published review notes wool's moisture-wicking properties create a less hospitable environment than synthetic fiberfill, though it hedges that broader bedding-material science is still debated.

The measured property here is moisture regain. Wool wicks up to 30% of its own weight in moisture vapor without feeling damp. That keeps the pillow microclimate near 40 to 50% relative humidity, below the threshold documented in a controlled humidity study as necessary for mite survival.

Shredded Dunlop latex relies on density without a test

Slow-pour Dunlop latex has a dense, closed-cell structure that offers mites little interstitial space or moisture retention. This is a plausible mechanism because loose fibrous fills trap humidity and skin debris, while a resilient solid does not. No study has tested shredded Dunlop latex against dust mites specifically.

The constraint that makes this fill rank second is that the inference relies on density and cell structure, properties that are measurable (typically 60 to 85 kg/m³ for Dunlop foam) but have never been correlated with mite colonization rates in a published trial.

Slow-pour Dunlop processing involves pouring liquid rubber into a mold and allowing it to cure slowly, which creates a denser base layer. The structural difference is real. The mite-resistance claim is extrapolated.

Buckwheat hulls are rigid but untested

Buckwheat hulls are non-fibrous and rigid, which gives mites little surface to burrow into or feed from. Allergy literature notes that loose, humidity-trapping fiberfill supports higher mite populations than dense material, but no buckwheat-specific study exists.

USA-grown, pre-polished hulls cut movement noise by up to 68% versus standard hulls, a measured acoustic improvement but unrelated to the allergy case. The mite-resistance angle rests entirely on the hull being a hard, dry surface instead of a soft, absorbent one.

This is the coolest fill of the six because air moves freely between rigid hulls. It is also the most adjustable for firmness since hulls can be added or removed through a zipper without changing the structural integrity of the fill.

Kapok has a fiber property with no supporting study

Kapok fiber has a natural hydrophobic wax coating that repels liquid water. The claim is that this creates a drier fiber-level environment, which may be less hospitable to mites. No AAAAI-cited or PubMed-indexed research evaluates kapok against dust mites specifically.

This makes kapok the least evidenced fill of the six. The wax coating is a real, measurable property. You can test water contact angle on kapok fiber and observe repellency. But the inference that this affects mite colonization has never been tested.

Kapok is wild-harvested from fallen, seasonally-shed seed pods, so it carries zero chemical processing. That matters to chemically sensitive buyers, but it does not strengthen the mite-resistance case.

Cotton relies on washability, not fiber chemistry

Cotton fiber itself has no dust-mite-specific resistance mechanism. Its defense is that an organic cotton cover can be laundered at 130°F (54°C), the temperature EPA guidance and the 1992 study both identify as effective.

This is the most honest framing of any fill in the list. The cover does the work, not the fiber. Cotton batting inside compresses over time and can lose up to half its original volume with use, but that does not affect the washability case.

Pairing cotton with a waterproof organic cotton protector creates a hot-washable barrier layer, which is the real intervention. The fill stays secondary.

When a lower-ranked fill is still the right choice

Wool's three-mechanism case does not matter to a vegan buyer who cannot use animal fiber at all. Shredded Dunlop latex's structural inference does not matter to someone with a latex allergy. A chemically sensitive buyer may choose kapok's zero processing over wool's stronger evidence, treating mite resistance as a secondary bonus rather than the primary reason to buy.

The ranking holds when mite resistance is the only constraint. It inverts when another factor overrides the mechanism strength. Diet, allergy, firmness need, or chemical sensitivity can each outweigh evidence.

Whichever fill wins for a given buyer, an allergen-barrier encasement and weekly hot-water washing still matter more than which fill has the best structural case.

What a measurement-first comparison looks like

Property	Wool	Shredded latex	Buckwheat	Kapok	Cotton
Moisture regain	Up to 30% by weight	Less than 5%	Minimal	Hydrophobic coating	Around 8%
Washable fill	No	No	No	No	No
Washable cover at 130°F	Yes	No (cold only)	No (cold only)	No (cold only)	Yes
Mechanism tested	Yes (humidity studies)	No	No	No	Not applicable
Third-party endorsement	Allergy UK	None	None	None	None

A number without a method is the thing a technical audience distrusts. The moisture-regain figure for wool comes from textile testing standards. The 130°F threshold comes from a peer-reviewed study with a sample size and a control group. The hydrophobic coating on kapok is observable under a microscope but has never been correlated with mite counts in a published trial.

That is the boundary between a defensible claim and an untested inference, and it runs straight through the middle of this comparison.

Originally published on Circadian.

Why Pillow Height Is a Per-Body Parameter, Not a Fixed Spec

Jacob Katz — Fri, 28 Aug 2026 10:30:12 +0000

The problem with standardized height

Most pillow manufacturers ship a fixed height: 5 inches for side sleepers, 3 for back sleepers, or whatever the factory decided would fit the median buyer. That approach ignores a measurement problem every chiropractor treating neck pain already knows: the distance between your ear and the mattress changes with shoulder width, mattress firmness, and body weight, so a single fixed number cannot work for everyone.

A 2023 clinical study of 84 people found that personalized pillow-height adjustment produced clinically meaningful neck pain reduction in about half of participants. That result supports treating height as something you measure and re-check rather than something a brand sets once at the factory.

This post walks through why height matters, what changes the number you need, and how to approach it as a parameter you adjust rather than a spec you buy.

What the measurement actually tracks

Pillow height is supposed to fill the gap between your neck's natural curve and the mattress surface, keeping your cervical spine in the same neutral line it holds when you stand upright: ears stacked over shoulders, chin level, no forward tilt or backward drop.

That gap changes based on three inputs:

Shoulder width. A wider shoulder creates a taller gap when you sleep on your side.
Mattress firmness. A softer mattress lets the shoulder sink deeper, which shrinks the gap.
Body weight. Heavier sleepers compress a mattress more, which also shrinks the gap.

Because all three inputs vary per person, the correct height is a function of your specific body and mattress, not a universal number.

Side sleepers versus back sleepers

Side sleeping opens a wider gap between the ear and the shoulder than back sleeping does, so peer-reviewed biomechanical research on side sleepers points to individualized height over a single chart number. A side sleeper's shoulder width determines how much height is needed to keep the spine level.

Back sleepers need less height because the gap between the back of the head and the mattress is smaller, but the same principle applies: the right height depends on neck length and how far the head sinks into the mattress.

Sleep position	Typical height range	Primary variable
Side sleeper	4–6 inches	Shoulder width
Back sleeper	3–5 inches	Neck curve depth
Stomach sleeper	1–2 inches or none	Cervical rotation tolerance

Stomach sleepers break the pattern entirely. Real height under the neck forces the head up and twists the cervical spine sideways for hours, so the correct height for a stomach sleeper is often close to none.

What changes the number over time

A pillow that worked for months can stop working when one of the three inputs shifts:

Mattress softening. A mattress that compresses more over its first year changes how far the shoulder sinks, which changes the height the neck needs. If the mattress gets softer, the same pillow height becomes too tall.

Weight change. Gaining or losing 10–15 pounds shifts shoulder width just enough to matter for side sleepers. Weight gain usually increases shoulder width, which increases the required height.

Mattress replacement. Switching from a soft mattress to a firm one changes how far the shoulder sinks, so the same pillow height that worked before is now too tall because the shoulder no longer compresses the surface as much.

A 2023 study found that periodic height re-adjustment mattered more than the initial setup, which is why adjustable designs with a side zipper exist: they let you reset height when the inputs change instead of buying a new pillow.

How adjustability solves the fixed-spec problem

Fixed-height pillows from brands like Tempur or Purple ship at one height, so a sleeper either fits the mold or does not. If your shoulder width or mattress firmness does not match the factory preset, the pillow cannot correct for it.

Adjustable pillows ship with extra fill—about a third more than most people keep—so height gets set through a side zipper on night one. When the mattress or body changes, height gets reset the same way: open the zipper, add or remove material, close it again.

That approach treats height as a tunable parameter rather than a fixed spec, which matches how chiropractors approach the problem: firmness and adjustability matter more than any one material or brand name.

Firmness interacts with height

A pillow can be the right height and still fail if the firmness is wrong. A fill that compresses too easily under the head's weight collapses the gap even at the correct starting height, so the neck sags overnight.

A 2025 systematic review found no single pillow type shows clear superiority for neck pain, disability, or sleep quality, which is why chiropractors generally weigh firmness and adjustability together. A firm fill that holds a contoured shape—like interlocking buckwheat hulls or slow-pour Dunlop latex—keeps the neck supported after the initial setup.

Softer fills like kapok or cotton compress more easily, which works well for stomach sleepers who need very little height but can cause side sleepers to lose support partway through the night.

Real-world re-adjustment example

Profile: side sleeper with a desk job, waking with a numb shoulder and stiff neck after 8 months on the same pillow. A mirror check showed the ear sitting well below the shoulder line, meaning the pillow had compressed below the height the shoulder gap needed. Adding fill through the side zipper brought the ear back in line with the shoulder, and the shoulder numbness resolved within 10 days.

Profile: someone who replaced a soft mattress with a firmer one 3 months ago and started getting mid-morning neck stiffness. The firmer mattress changed how far the shoulder sank, so the same pillow height that worked before was now too tall. Removing a small amount of fill through the zipper brought the neck back to neutral within a few nights.

The method, not the brand

Chasing a single "best chiropractor pillow" misses that the right answer depends on your shoulder width, your mattress, and how those inputs change over time. The method that works is measuring the gap, setting height to match, and re-checking when something changes.

Every number in this post comes from peer-reviewed research on cervical biomechanics or clinical trials on personalized pillow adjustment. The consistent finding is that fit matters more than brand, and adjustability matters more than any one fixed spec.

Originally published on Circadian.

GSM is an input, tog is an output, and the label prints them side by side

Jacob Katz — Tue, 25 Aug 2026 20:13:17 +0000

Two numbers get printed on the same duvet label. One is grams per square meter. The other is a thermal resistance rating. Shoppers read them as two dialects of the same measurement, pick the bigger one, and buy the wrong duvet.

They are not the same measurement. There is no conversion between them, and the reason is the kind of thing that shows up in any system where a raw input gets treated as a measured output.

GSM is an input

GSM is grams per square meter of fill. A manufacturer weighs a one-square-meter sample of the finished fill layer and records the grams. A duvet listed at 350 GSM holds 350 grams of fill in every square meter of shell fabric.

That is a quantity. It describes what went in. It says nothing about what comes out, because the same 350 grams behaves differently depending on what the grams are made of. Wool fiber traps air one way, a down cluster another, cotton batting compresses into a flatter and denser layer than either.

There is also a units trap hiding in it. GSM is a rate, per square meter. Total fill weight scales with the surface area of the duvet. A King at 350 GSM weighs more than a Twin at 350 GSM, because a King covers more square meters. Two brands can both publish "350 GSM" and mean different things by it, since one may have weighed the finished duvet and the other only the raw fill before quilting. Nothing requires either of them to say which.

Tog is an output

Tog comes out of a lab. It is measured under British Standards Institution method BS 4745:2005, the two-plate test: a sample sits between heated plates, and the power the plate needs to hold a set temperature difference gets converted into a tog value. A fabric that resists heat loss better needs less added power. One tog is defined as roughly the thermal resistance of a medium-quality blanket.

The important property is that tog is a result. Every fabric construction has to sit through the plate test on its own before it earns a number. You cannot look it up from a spec sheet, because the spec sheet is the input and tog is what happens after the input meets a physical process.

Why there is no conversion function

Put the two side by side and the problem is obvious:

	GSM	Tog
What it measures	mass of fill per square meter	thermal resistance
Unit	g/m²	tog (defined against a reference blanket)
Where it comes from	a scale	BS 4745 two-plate lab test
Depends on fiber type	no	yes
Depends on fill height and construction	no	yes
Scales with duvet size	no, it is a rate	no
Can be derived from the other	no	no

A conversion needs a function. This one would need tog = f(gsm), and every honest version of f requires arguments the GSM number does not carry: fiber type, fill height, construction, how the layer was quilted. Fix those and you have not derived tog, you have described a specific product, which then has to go through the plate test anyway.

So a vendor chart offering a fixed GSM-to-tog conversion is doing something specific. It is publishing the output of a lab test that was never run.

What we publish instead

We make duvets, so this is the part where I say what we do about it. We do not print a tog number, because we have not paid for per-product BS 4745 testing and an estimated tog is a made-up lab result. We publish the total fill weight for the size you are buying:

Size	Organic Cotton Duvet	Organic Wool Duvet
Twin	about 7.5 lb	about 6.5 lb
Queen	about 10 lb	about 9 lb
King	about 12 lb	about 11.5 lb

Wool comes in lighter at every size and still regulates temperature, because wool wicks up to 30% of its own weight in moisture while staying dry to the touch. That is a fiber property doing work that raw weight would otherwise have to do. It is also exactly the effect that collapses any attempt at a universal conversion.

Both are GOTS Certified Organic under license GOTS-10229, which covers the fill and the sateen shell together rather than the outer fabric alone.

The general shape

The failure here has nothing to do with bedding. A raw input and a measured output get printed in adjacent fields, with no type information saying which is which, and the reader assumes adjacency implies comparability.

If you have ever seen someone compare a configured cache size against an observed hit rate, or treat an allocation against a benchmark result, it is the same mistake wearing a duvet cover. The input is cheap to publish and the output is expensive to measure, so the market fills up with the cheap number and everyone quietly reasons as though it were the expensive one.

The tell is always the same, so it is worth asking directly: what physical process produced this number? If the honest answer is that nothing did, and someone simply weighed the ingredients before they went in, then what you are holding is an input wearing an output's clothes.

Originally published on Circadian.

The pillow you keep

Jacob Katz — Fri, 10 Jul 2026 15:05:04 +0000

Somewhere in a closet you probably have the evidence: a pillow you bought with real hope, slept on for a few good weeks, and then slowly gave up on. It did not break. It just quietly caved in, a little more every night, until one morning you were sleeping in a dent and pretending you were not. So you bought another one. That cycle, six to twelve months a pillow, is so normal that most people never question it. It took me a while to see that the whole thing is a materials problem, and that it does not have to be yours.

Here is the part that surprised me when we started making these. The story everyone tells about natural pillows is that they go flat. It runs the other way. A synthetic or foam pillow is built from material that compresses and stays compressed, so it has a shelf life measured in months. A dense natural fill starts firmer, recovers better, and then, because you can open it, refuses to be finished when it finally settles.

The lifespans are not close. Cotton, the densest fill we make, holds its shape for two to four years against six to twelve months for a synthetic. Wool has a natural crimp, a built-in coil in every fiber, so it springs back morning after morning for three to five years. Buckwheat hulls last three to five years too, and when they wear down you order a bag of fresh hulls for a fraction of a new pillow and keep the cover you already broke in. Slow-pour Dunlop latex is the marathon runner, up to a decade. Kapok, the soft one, stays lofty for years on a five-second daily fluff.

But the number I care about most is the one with no end date. Every pillow we make ships overstuffed, about thirty percent more fill than most people want, with a zipper down the side. That zipper is not a gimmick for setting the height on day one. It is how the pillow stays alive. When it settles, you knead the fill back to the center, and most of the loft comes right back, because the material was never gone, just packed to the edges. If it needs more, you add a handful from a refill pack. You are restoring a pillow you already know fits your neck instead of gambling on a new one.

Cleaning works the same way. The organic cotton cover unzips and washes in cold water, which is where the sweat and skin end up anyway, and the fill stays dry inside. You never wash the fill itself. A washable cover over a dry, refillable fill is a pillow you can keep clean without slowly destroying it, which is the opposite of a sealed foam block you cannot open, cannot clean inside, and cannot refill when it sags.

So when someone asks how long one of our pillows lasts, the honest answer is years, and then longer, because you refresh it instead of replacing it. Add fill through the zipper, wash the cover, air it in the sun a few times a year. The pillow you buy becomes the pillow you keep. That is the whole pitch, and it is the one part of this business I never get tired of explaining.

Every Circadian pillow has a GOTS certified organic cotton cover, license GOTS-10229, issued by Oregon Tilth. On the wool and cotton pillows that certification covers the whole pillow, fill included. Everything is handmade in our New Jersey workshop.

Circadian makes natural, adjustable pillows, handmade in New Jersey, with a 60-night trial and free shipping both ways. Explore the collection, or read the full breakdown of how long each fill lasts and how to keep it like new.

Originally published on Circadian, a natural bedding brand handmade in New Jersey. Read the full guide with sources: https://circadianrest.com/blogs/pillow-talk/the-pillow-you-keep.

Non-toxic is a claim. The certification is the receipt.

Jacob Katz — Fri, 10 Jul 2026 14:40:36 +0000

The question I get more than any other arrives in some version of this: is this thing going to gas out my bedroom the way the memory foam pillow I just threw out did? Fair question. A lot of people have spent two weeks sleeping next to a smell they could not place, and they want to know if they are about to do it again.

Here is the short version. Off-gassing is a specific thing, not a vibe. It is a synthetic material releasing volatile organic compounds into the air, the sharp chemical note you get when you unwrap a new foam pillow. Memory foam is polyurethane, a petroleum foam built from a stack of chemicals, and it keeps shedding small amounts of them as it airs out. The material is the source, so it does this the whole time it breaks down.

A cotton or wool or kapok pillow has no petrochemical in it to release. These are fibers that were grown, not synthesized. A new cotton pillow shows up close to odorless, because there is no plastic to smell.

The part people trip on is scent. Wool has a faint lanolin note when it is new, and latex can carry a light rubber-tree smell on the first day. That is the raw material smelling like itself, and it clears within a few days. It is a different event from a foam pillow shedding manufactured compounds for weeks. Different source, different thing.

The trouble is that "non-toxic" and "natural" are unregulated words. Anyone can print them on a label. So I stopped asking people to trust the words and started pointing them at the receipts.

We lean on two. The first is GOTS, the Global Organic Textile Standard, under license GOTS-10229, issued by Oregon Tilth. GOTS audits the whole supply chain, from fiber to finished pillow, and bans formaldehyde, carcinogenic azo dyes, toxic heavy metals, and chlorine bleaching. On our cotton and wool pillows that certification covers the fill, not just the cover, which is the part most brands quietly leave out. You can look the license up yourself in the public database. One honest note so it does not read as a trick: the record shows the New Jersey workshop that makes the pillows, not the word Circadian, because that workshop holds the license. The pillows are made under it.

The second is OEKO-TEX Standard 100 at Class 1, which our slow-pour Dunlop latex carries on its fill. Class 1 is the strictest tier, the limits set for products made for babies and toddlers up to three years old. Most bedding only needs to clear Class 2. The rubber-tree source is FSC certified on top of that.

So when someone asks me whether our pillows are non-toxic, I try not to answer with an adjective. Non-toxic is a claim. GOTS-10229 and OEKO-TEX Class 1 are the receipt. Look them up before you trust anyone, including me.

When the material is clean, the best review is the one nobody thinks to write, because the only thing you notice is that you do not notice anything. For a pillow, that is the whole point.

Watch the full conversation, Are natural pillows non-toxic, and what off-gassing really means, or browse the GOTS Certified Organic pillows. Every Circadian pillow ships with a 60-night trial and free returns, handmade in our New Jersey workshop since 1981.

Originally published on Circadian, a natural bedding brand handmade in New Jersey. Read the full guide with sources: https://circadianrest.com/blogs/pillow-talk/the-receipt-behind-non-toxic.