Tog is a measurement of how thermally insulating, and therefore warm, a duvet is. A high tog (10.5-15) is better for winter, while a low tog (1-4) will be light enough for summer. Some duvets come in 'four-seasons' or 'all-seasons' sets. With these you get one light duvet (usually about 3.5 tog) and one heavier one (usually about 10.5 tog). The light one will be enough in hot summer months, and the heavy one suits spring and autumn weather. When you need extra warmth in winter, you can combine both. Standard UK duvet sizes One downside to all natural duvet fillings, including feather and down, is that you shouldn’t wash them at home as they can lose their filling more easily and are difficult to get completely dry afterwards. If they are cared for properly and professionally laundered, feather and down duvets can last more than twice as long as synthetic alternatives. Wool duvets: pros and cons

Hollowfibre or microfibre polyester duvets are the most popular type among Which? members – nearly half own one of these. Get help deciding what to buy with our guides to the best mattresses and the best pillows. Duvet types explained Organic cotton: a fantastic choice for those with sensitive skin, organic cotton is pesticide free, hypoallergenic, pigment-free and therefore void of any harmful finishing chemicals such as bleach and formaldehyde. Though hypoallergenic duvets won’t be filled with cotton alone, they are often encased in organic cotton for extra protection against allergens. Having the right duvet can help make the difference between a difficult night's sleep and a peaceful one. Just over half of our survey respondents had bought a new duvet during the past five years.Cons: Can be expensive, needs to be washed gently at a low temperature, can seem flat in comparison with other fillings Wool is a less common choice of duvet filling. It's similarly priced to feather and down, and excellent at retaining warm air, keeping you warm when cold and removing heat and moisture when you’re warm. Unlike feather and down, it’s naturally hypoallergenic and resistant to dust mites. verifyErrors }}{{ message }}{{ /verifyErrors }}{{ Washing at lower temperatures can dissolve the dust mite droppings that trigger most people's reactions, which will fix the issue temporarily. However, to kill the dust mites themselves, you need to wash at 60C or above. but the mites will survive, so it's not a long-term solution. Aim to wash your duvet every six months (bedding that sits against your skin covers – so sheets, duvet covers and pillowcases – should be washed weekly or fortnightly). Just to spell it out: any duvet that proclaims itself ‘anti-allergy’ but is not washable at 60C is no such thing. 2. Look for 'anti-allergy' rather than 'hypoallergenic' It's one of the lightest and most supple fillings, meaning even a 14-tog microfibre duvet will feel light. Some people prefer this as the duvet won't feel heavy on you as you sleep, while others prefer a heavier, more closely hugging duvet. If you're not sure which you'd prefer, make sure you try them out in store before buying.

Microfibre duvets are a relatively recent addition to the market, but they aren't to be confused with hollowfibre. Microfibres are finer but don't have the hollow space that hollowfibre has. Instead, microfibre is intended to be a synthetic equivalent to down; its extra-fine fibres give the same feel. Feather/down duvets are also very popular, owned by around a third of members. Less popular types include wool, silk and other synthetic duvets. As you’d expect, it’s a belief that tends to be propagated by the makers of synthetic duvets, and hotly disputed by the makers of down ones! It should also not be confused with the fact that some people are specifically allergic to feathers themselves (the numbers affected by this problem are relatively small). Hypoallergenic means that the actual material and filling of the duvet isn't made of a known potential allergen, like feathers or wool. But other allergens, mainly dust mites, can still develop on these types of duvets.Anti-allergy means the filling and casing will have been treated to resist and combat the development of dust mites. You might find that this type of duvet is good for you if you have asthma, eczema or rhinitis, all of which could be exacerbated by allergens. Often viewed as the height of luxury, silk duvets are naturally hypoallergenic and resistant to dust mites, and therefore ideal for people with eczema or asthma. Like wool, silk will help you stay cool in summer and warm in winter. Like all natural fillings though, they will need to be professionally laundered. Microfibre duvets: pros and cons Anti-allergy, in contrast means that the duvet has been specially treated to prevent the development of dust mites, protect against dust-mite infestation, or both. Cons: More expensive than hollowfibre, has to be professionally laundered, some people can be allergic to the filling

When shopping for duvets, you often see the terms ‘hypoallergenic’ and ‘anti-allergy’, and may assume they’re interchangeable. However, they are actually very different. Hypoallergenic, or non-allergenic, means that the materials used are relatively unlikely to cause an allergic reaction. This doesn’t mean, though, that the manufacturer has applied any specific treatments to the duvet to prevent allergies. You'll know your duvet is due for an upgrade when the filling becomes limp or uneven, or it starts coming through the casing.These all correspond to different mattress sizes. If you tend to feel cold in bed, go for the next size up from your mattress size (for example, if you have a double bed, use a king-size duvet), so that the duvet flows over the edges to keep warm air in and any draughts out. As the name suggests, feather and down duvets combine feathers, the outer part of a bird’s plumage, with down, the lighter, fluffier fibres that lie beneath feathers and provide insulation. The ratio of feather to down will affect the duvet's warmth and price. More than a third of Which? members surveyed choose feather and down duvets, making it the second-most popular option. These lightweight, cosy duvets retain heat well but still help you to avoid overheating. Plus, if cared for properly, they will last much longer than synthetic fibre alternatives.