Do the feathers in a down sleeping bag deteriorate over time, causing fine dust and potential allergies to its user?

  • 7
    Isn't that a rule or something? If it exists, there is someone with an allergy to it?
    – Max
    Jan 31, 2023 at 7:40
  • Related may also be the idea that people's allergies can change every 7 years. I have heard this numerous times, but so far, I have not had sufficient research time to to determine whether this is current scientific belief or just another urban legend. Jan 31, 2023 at 10:05
  • 1
    BTW, you may want to "sniff the bag". Sleeping bags are notorious for harbouring mold. Giving it a few sniffs is by no means a perfect or reliable test, but doing so is free and easy. Jan 31, 2023 at 10:08
  • 4
    @RockPaperLz-MaskitorCasket I can speak from personal experience that allergies changing over time is totally possible. My allergy to cats has lessened significantly, I developed a new allergy for pears (only when eaten raw, not when cooked/baked). My hayfever is a constant thing but it waxes and wanes. Is very low now, but I had it very bad when I was 15-20 and later in my mid-thirties. But every 7 years (or any other fixed time-frame) is total nonsense.
    – Tonny
    Jan 31, 2023 at 13:07

2 Answers 2


Certainly, however, as the linked paper confirms, that you are much more likely to get have an allergy to dust mites rather than feather allergy alone.

Dust mites are commonly found in bedding and regularly used, but infrequently washed items, like sleeping bags, can contain high levels of dust mites/dust mite allergens. However, studies on new products indicate that initially at least (90 days for daily use pillows), and using modern fabrics/weaving techniques, dust mites and dust mite allergens are actually less common in feather sleeping products than in synthetic products. This seems to be because the feathers are washed and dried before packing and feather-impenetrable (and coincidentally also mite impenetrable) fabrics and weaves are used, whereas synthetics do not use the feather impenetrable fabrics, so the mites can get in.

  • My understanding is that the mites live off of skin particles. That is, the 'dust' that is relevant is our dead skin. It's not clear what they would be eating in the case of an old item in storage but I suppose they could be dormant.
    – JimmyJames
    Feb 1, 2023 at 17:41
  • @JimmyJames the allergens are mostly dust mite faeces and partially digested matter. They feed on shed skin cells from humans and other animals as well as some common household fungal species (molds). Apparently they live for about 70 days and lay a bunch of eggs, and so long as there is food, there will be mites. I don't know how much food a single use of a sleeping bag might produce, but I bet it is enough for a fair number of mites over at least a year.
    – bob1
    Feb 1, 2023 at 20:17
  • 1
    1 year sounds reasonable. But 35 years, though? Mold could be present in storage, I suppose. It seems to me that a bag that is in regular use is likely to be able to support more mites than one rolled up and stored in a dry place.
    – JimmyJames
    Feb 1, 2023 at 20:22
  • 1
    @JimmyJames I doubt the bag has actually been in storage for 35 years and we don't know how often it was used prior to that or the storage conditions. I read it as the bag was 35 years old. I also don't know how well the allergens persist in the environment, probably pretty well given that they are largely insoluble proteins.
    – bob1
    Feb 1, 2023 at 20:26
  • Good point. Not sure why I was thinking it was in storage the whole time. I guess the point is that the 'dust' that causes most allergies comes from us and our pets. It's not dirt or ashes etc. Now I'm wondering if mites could consume feathers directly or in a broken-down state.
    – JimmyJames
    Feb 1, 2023 at 20:32

You can have allergies to a brand new down bag. If you have down allergy it doesn't really matter the age. Old might be worse (don't have evidence either way), but an allergy is an allergy. Down "allergies" are usually just allergies to the dust that the down collects. So an old down bag is probably just really dusty which is causing a reaction. If you need the bag going forward, then you're probably best washing it with special down wash (example). Down doesn't deteriorate a whole lot over time. It should have a lot of the original structure/loft/function 35 years later as long as it's been handled well over the years.

  • Down certainly wont retain its original structure/loft even after a couple of years. I know this from decades of owning high quality, all down bedding. The fine down escapes the bedding on a daily basis, during general use and especially during the required "fluffing". Whether it "deteriorates a whole lot" I wouldn't know since I've never researched it.
    – John
    Feb 1, 2023 at 16:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.