Sweat doesn’t cool you till it evaporates. A sheet’s job is to move moisture somewhere it can evaporate; however, most materials marketed on that premise do the exact opposite. A moisture-wicking sheet set helps to move liquid along or through a fabric so it can evaporate from a larger surface. It does the opposite of resisting it, and it’s not the same as absorbing it.
While regular polyester mostly repels, cotton and linen absorb, lyocell and viscose absorb and spread, and engineered polyesters wick along the fiber surface.
Why is any of this important?
In bed, your body can release heat in two different ways. It can transfer heat straight into anything it comes into contact with, but it does so slowly and ceases to function as soon as the surface reaches your body temperature. Alternatively, it may quickly evaporate water from your skin, which is why a breeze feels dramatic on wet skin and dull on dry skin. The one that bedding may either help or damage is evaporation, which is by far the more potent of the two. Because the air directly above it is already saturated, sweat resting in a film on your skin beneath a sealed cloth does very little for you.
Because sweat evaporates quickly, real heat is eliminated when it is absorbed into a garment and spread out over a wide region.
Therefore, what a sheet does with water is a more useful question than whether it feels cool.
The marketing blurs the line between rows three and four the most, and this is important. They are both made of polyester. Due to its hydrophobic nature and fixed chemistry, polyester does not absorb water.
Engineered wicking fabrics circumvent this by shaping the fiber, typically with channels or a modified cross-section, so that liquid spreads out to dry and travels along the outside by capillary action.
That structure is absent from regular polyester. Microfiber sheets feel clammy because they just don’t carry water, which is why we avoid them.
Which is better, wicking or absorbing?
These are suitable for various issues; therefore, it’s important to know which one you have.
- Absorption
Absorption has a large capacity. Because linen absorbs water more slowly than cotton, it can withstand a hot night better than anything else. Cotton may absorb a lot of water into the fiber before it feels wet. The trade is drying speed: a moist sheet is uncomfortable, a worse insulator than a dry one, and a saturated natural fiber remains damp.
- Wicking and spreading
The most beneficial activity for most individuals is wicking and spreading, which is what lyocell and excellent viscose do. Moisture enters the fiber and spreads sideways, evaporating from a wide region rather than concentrating in one patch.
Additionally, those who loathe sharp percale typically appreciate its cool, silky handfeel.
- Surface wicking
Even on a site that is normally cold on synthetics, surface wicking in an engineered polyester merits its position for genuinely intense sweating because it dries the fastest of all.
The truth is that drying speed outpaces capacity if you wake up with the bed truly wet rather than just warm; cooling sheets are the best option for night sweats.
Anti-sweat, sweat-resistant, sweat-proof
These expressions lack a standard and an agreed-upon meaning. Read them as marketing for one of the mechanisms listed above, and determine which by looking at the fiber content, which merchants are required to disclose.
For example, sweat-resistant is ambiguous in an important way: it can refer to a fabric that effectively transports moisture away or one that repels it and leaves it on your skin.
