Most duvets are made with down (or a combination of down and feathers), synthetic fibre or natural fibre fillings.Each has its own merits and the capability of staying cool throughout the winter, but a lot of it comes down to personal preference. Here’re the highlights for each:Down: Certainly among the most luxurious bedding options, down is a natural insulator that can also be super lightweight and therefore comfortable during the warmer months. Often mixed with feathers, down duvets aren’t vegan and can agitate those with allergies if not cared for properly.Synthetic fibre: While nothing quite compares to down, synthetics are designed to mimic down. Typically hypoallergenic, synthetics tend to be more affordable, although as textile technologies become more advanced, a synthetic fibre duvet can still cost quite a bit.Natural fibre: Including wool, bamboo, silk, linen bedding and more, natural fibres can be a good option for cool bedding. Wool and bamboo are particularly well suited for the warmer months and are typically allergy-friendly.