Compared

Each comparison names its basis before its finding, and every figure links to the page it came from.

Does wool handle night-time damp better than cotton or polyester?

As vapour, yes. Woolmark says wool fibres take up about twice the water vapour cotton does and thirty times what polyester does.

That figure is from the wool industry's own body (Woolmark). The sleep evidence is thinner. In the one lab trial that swapped bedding, wool against polyester, there was no bedding effect on sleep, though wool sleepwear shortened the time taken to fall asleep (Shin and colleagues). The guide on wool and moisture at night goes further.

Wool or a synthetic fill for dust mite allergy?

Neither has a wool pillow study behind it. The pillow studies that exist compared synthetic fill with feather.

An allergy clinic summarises three studies in which synthetic pillows built up mite allergen faster than feather ones (The Asthma & Allergy Center). No study found for this site measured mite allergen inside a wool pillow, so the case for wool rests on a humidity argument. The wool pillow buying guide sets out what a cover can do instead.

Wool alone, or wool over buckwheat hulls?

Hulls add firm, shapeable support and a lot of weight. The wool layer softens the surface and quiets the rustle of the hulls.

One hull seller says a standard all-hull pillow takes about a 10-pound bag of hulls (PineTales), so a two-fill pillow is far heavier than an all-wool one. The only head-to-head buckwheat pillow trial found followed 30 older adults for two weeks, and it tested plain hulls with no wool top (Korean Journal of Health Promotion). The wool and buckwheat guide covers both layers.

Batting, balls or loose fill?

Batting holds one shape and settles early. Balls let you set the height yourself. Loose tufts are soft but clump more easily.

Fill weights compare fairly only within one form, because balls and layers hold air differently. The guide to the three fill forms has the seller figures.

Does the country on the label matter?

Less than the fibre it hints at. New Zealand's clip runs mostly coarse and Australia's mostly fine, and the micron says more about the feel than the flag.

New Zealand's testing authority puts most of the national clip at 30 to 40 microns (NZWTA), while Australian testing for the 2025/26 season showed a 20.5 micron mean (AWI). The guide on wool by country of origin adds the US clip.