Suggest Why would a duvet keep you less warm if it has been flattened?

A flattened duvet loses its insulating ability because the fill material, such as down or synthetic fibers, is compressed and unable to trap air effectively. Air pockets are crucial for insulation, as they create a barrier against heat loss. When the duvet is flattened, the reduced volume means less air is trapped, resulting in decreased warmth retention. Consequently, the duvet provides less thermal insulation, keeping you cooler than when it is fluffed.