Moisture Vapor Transfer (MVT) is the process that allows your body heat and moisture to escape your sleep microclimate as vapor — long before it turns into liquid sweat. When bedding materials have high MVT, they let humidity move freely away from your body, preventing the clammy, damp feeling that wakes hot sleepers. Wool is exceptional at this because its fibers are naturally crimped and porous, allowing vapor to pass through continuously without collapsing under your body weight.

Most moisture-wicking sheets only react once sweat appears. They pull liquid off the skin, but they do nothing to stop the sweating in the first place. High MVT bedding—especially wool—prevents sweat from forming by managing vapor before it condenses. This is the difference between staying cool all night vs. waking up soaked at 2 a.m.

They help a little, but only after the sweating begins — which is why so many people still wake up sweaty even with moisture-wicking sheets. These fabrics (usually bamboo, microfiber, or performance synthetics) handle liquid sweat, not vapor. Wool’s MVT performance stops overheating at the root by preventing humidity buildup, which moisture-wicking sheets cannot do.

Wool fibers can absorb up to 30–35% of their weight in moisture vapor without ever feeling wet. This vapor is pulled into the fiber core, then released into the air as your temperature shifts. It’s a dynamic, self-regulating system that no plant-based fiber or synthetic fabric can replicate. This is why wool bedding stays dry to the touch even when humidity rises.

Cotton and bamboo absorb liquid moisture, not vapor. Once sweat appears, these sheets soak it up like a sponge and hold onto it, flattening their airflow pathways. This traps humid air around your skin, increases sweating, and leads to that sticky, damp, uncomfortable feeling. They breathe — but they don’t regulate.

Yes — especially for severe night sweats or hormonal changes (menopause, thyroid conditions, postpartum, high athletic metabolism). Wool’s MVT performance keeps bedding dry, prevents humidity spikes, and stops that cold-sweat crash when damp sheets meet cool air. The result is steadier temperature, fewer wakeups, and deeper sleep cycles.

No. Wool isn’t “warm bedding” — it’s responsive bedding. When you overheat, wool releases heat and vapor quickly, preventing sweat from forming. In hot climates or warm bedrooms, it actually keeps your microclimate cooler than cotton, bamboo, down, or synthetic alternatives. That’s the power of true thermoregulation.

Down, polyester, microfiber, viscose rayon (bamboo-derived), and tightly woven cotton all score poorly in MVT. They trap humidity, collapse under pressure, and prevent vapor from escaping. This leads to overheating, sweating, and disrupted sleep. These materials often feel cool for the first 10 minutes — until humidity builds.

Yes. High-MVT bedding like wool adapts to each person’s temperature independently. It moves vapor away from warmer sleepers, prevents spikes in humidity, and balances the microclimate across the bed. Couples who fight over blankets or run at different temperatures benefit hugely from wool’s self-adjusting performance.

For the strongest vapor transfer and lowest risk of night sweats:

• Wool comforter: your primary MVT engine

• Organic cotton sheets: breathable base layer

• Minimal layering: avoids trapping vapor

• Open airflow: allow wool’s crimped structure to breathe

• Healthy room humidity (40–50%) improves natural evaporation

This combination gives your body everything it needs for true heat release, not just moisture wicking.