Long sleeved nightwear rather than an extra duvet

Short answer: A long-sleeved set and a pair of socks beat an extra duvet. It keeps warmth close to the body without you getting too warm in the middle of the night, the way a thick duvet often does.

Layers close to the body

Warmth is held best close to the skin, not on top of it as more fabric on the outside. A thin long-sleeved layer therefore often warms more in practice than a thick duvet piled on top. See bamboo sleepwear for women for a long-sleeved set for cold nights.

Socks do the most work

Cold feet are the most common reason you cannot fall asleep in a cold bedroom in winter. A pair of socks often solves the problem on its own. See bamboo socks for women for a thin pair that does not squeeze.

Avoid the thick option

Thick sweat fabric warms you at first and turns clammy afterward once the body starts sweating under the duvet. Thin, long-sleeved bamboo viscose is the better option. See bamboo sleepwear for more styles in thin material.

Adjust with the bedding

If you are still cold after switching to long-sleeved sleepwear and socks, change the duvet rather than adding more clothing. See bamboo bedding for a warmer duvet for the coldest nights.

Why layers beat thickness

A single thick layer insulates worse than several thin ones, because the air between the layers also holds heat. It is the same principle used in outdoor winter clothing.

Sleeve and leg length must fit

Sleeves or legs that are too short leave a cold band of uncovered skin. Choose a size where sleeves and legs stay fully covered even when you stretch out in your sleep.

Hands are harder to keep warm

Hands give off a lot of heat and are hard to cover fully without it being annoying. Here it helps more to warm the bedroom slightly than to add extra clothing.

When an extra duvet is still the right call

In a very cold room where even several layers of clothing are not enough, an extra light duvet on top of your usual one can work well without making you too warm.

Test it over a few nights

Start with one long-sleeved set and a pair of socks, and adjust from there. Most people find the right combination after a few nights of adjusting layers and duvet.