Feather and Down Duvets: The Real Problems, and the One Everyone Gets Wrong

Down duvets have three real problems, and they all come back to moisture. Down absorbs very little of it, which makes the duvet hard to wash, easy to ruin, and warm in a way some people find stifling. The fourth problem, the allergy one you have probably read about, is not a problem at all. The evidence points the other way.

That last part matters, because it is the argument almost every wool brand uses, and it is wrong.

Does feather and down bedding cause dust mite problems?

No. Synthetic bedding accumulates more dust mite allergen than feather bedding does, and the best evidence for that was collected in New Zealand.

In 2002, researchers measured dust mite allergen in 65 duvets, 81 pillows and 65 mattresses across 34 New Zealand households. Synthetic pillows and duvets yielded significantly more allergen than feather pillows and duvets, about 7-fold and 15-fold respectively. Their conclusion was blunt: advising house dust mite sensitised people to use synthetic bedding does not prevent house dust mite allergen exposure.

An earlier study put paired synthetic and feather pillows on the same twelve beds and left them for a year. After twelve months the synthetic pillows held 19.28 micrograms of allergen per gram against 6.45 for the feather pillows.

A third study found that raw, unprocessed feathers do carry dust mite allergen, but commercial washing removes it, and that feather pillows did not internally accumulate allergen when used in mite-infested bedrooms over three months.

Dust mites live on skin flakes in warm, humid conditions. They are in your mattress, your carpet and your pillow regardless of what the filling is made of, and the filling has less to do with it than the humidity of your bedroom.

There is one real feather allergy, and it is different. Some people react to the feather protein itself. It is uncommon, it is not the same as a dust mite allergy, and if you have it you already know. For everyone else, this is not the reason to avoid down.

So what is actually wrong with down duvets?

Three things, and they are all consequences of the same property.

Down is an extraordinary insulator for its weight. It is not an extraordinary handler of moisture. A down cluster holds somewhere around five to eight per cent of its own weight in moisture. Wool holds up to a third. Polyester holds under one per cent.

You lose about half a litre of water vapour a night through skin and breath, without sweating at all. In a down duvet, most of that has nowhere to go.

Washing a down duvet is genuinely difficult

This is the problem nobody mentions at the point of sale.

A down duvet holds a great deal of water. Drying it takes two to three full dryer cycles on low heat, pausing between each to pull it out, shake it and redistribute the fill. Air drying takes 24 to 48 hours and carries the risk that the inner fill never fully dries even when the outer cover feels dry.

Two things go wrong from there, and both are permanent.

Detergent residue. Soap left in the down coats the clusters and stops them re-lofting. The duvet comes out looking clumped, and the only fix is to wash it again.

Heat. High heat mats the down. A matted clump feels dense and stays a lump no matter what you do, and high heat is the single most common way people destroy a down duvet while trying to rescue it.

Store it damp and you get mildew. Store it in a vacuum bag and the compression crushes the clusters, with the loft taking months to recover, if it recovers.

This is why most down duvets are sold with instructions to have them professionally cleaned, and why most people simply never wash theirs.

Why down duvets go lumpy

Down is loose fill. It is sewn into baffles or channels precisely because loose fill moves, and over years it moves anyway. It drifts toward the foot of the bed, gathers in corners, and leaves the middle thinner than it was.

A thin patch is a cold patch, no matter how much down the duvet contains in total. This is the most common complaint about duvets that cost several hundred dollars and were perfectly good when new.

Why down can sleep hot

Down traps a great deal of still air and holds very little moisture. In a cool, dry bedroom that is close to ideal. In a warm or humid one, the heat has nowhere to go and neither does the vapour you are producing, and the air under the duvet turns warm and damp.

Humidity is what wakes people, more than heat on its own. You surface, push a leg out, pull the covers back, and never quite work out why.

When a down duvet is still the right choice

It genuinely is, sometimes, and it is worth saying so.

If your bedroom runs cold and dry, if you want the lightest possible duvet for the warmth it gives, if you like the cloud-like loft, and if you are content to have it professionally cleaned, down is very hard to beat. Nothing else gives that much warmth for that little weight.

The question is whether those conditions describe your bedroom.

Where wool is different

Wool holds up to a third of its own weight in moisture out of the air and gives it back again. That single property is behind most of the differences.

It means the air under the duvet stays drier. It means the duvet can be washed at home on a cold wool cycle rather than sent away. And in a needle-punched wool duvet, the fill is a single bonded sheet rather than loose clusters, so there is nothing inside that can drift to one end or clump in a corner.

Do Not Disturb makes its wool duvets this way, from New Zealand strong wool needle-punched into one continuous sheet. Known in Australia as a wool quilt or doona.

The honest caveat is that a wool duvet will not look as lofty as a down one. Craig, a customer in Invercargill, put it better than we could when he swapped his 90/10 goose down inner for a 350gsm wool one:

I had my doubts on whether a 350gsm wool duvet inner could compete with my 90/10 goose down duvet inner. I became more concerned given the significant difference in loft. However, tested on the coldest of Invercargill nights the wool duvet inner outperformed the goose down.

Loft you can see and warmth you can feel are not the same thing.

For a fuller comparison across all three fillings, including synthetic, see wool vs down vs synthetic.

What this means for you

If you have been avoiding down because of allergies, the evidence does not support that reason. Look at your bedroom's humidity instead, which matters far more.

If you are choosing now, the real questions are how warm and how damp your room gets, and whether you are willing to have a duvet professionally cleaned. Cold and dry, and content with the care: down is excellent. Warm, humid, or you want to wash it yourself: it is the wrong tool.

And if your current duvet has gone lumpy, that is not you doing something wrong. It is what loose fill does.

FAQ

Are feather duvets bad for asthma? Not on the dust mite evidence. New Zealand research found synthetic duvets held about fifteen times more dust mite allergen than feather ones. If you have a genuine allergy to feather protein, which is uncommon and distinct from dust mite allergy, that is a different question and worth discussing with your doctor.

Can you wash a down duvet at home? Sometimes, with a large front-loading machine and a great deal of patience. It needs a gentle cycle, a double rinse to remove all detergent, and two to three low-heat dryer cycles with breaks to redistribute the fill. Getting any of that wrong tends to be permanent, which is why most manufacturers recommend professional cleaning.

Why has my down duvet gone flat and lumpy? Loose fill migrates over time, and washing or drying it badly accelerates it. Detergent residue stops the clusters re-lofting and high heat mats them together. Matted down does not come back.

Sources

• Siebers R, Fitzharris P, Crane J. House dust mite allergen levels in individual bedding components in New Zealand. 2002.

• Rains N, Siebers R, Crane J, Fitzharris P. House dust mite allergen (Der p 1) accumulation on new synthetic and feather pillows. Clinical & Experimental Allergy, 1999.

• Dryer AL, Chandler MJ, Hamilton RG. Dust-mite allergen removal from feathers by commercial processing. Annals of Allergy, Asthma & Immunology, 2002.

• Sleep Foundation, How to Wash a Down Comforter.