Then there are the more traditional, natural fillingsto consider. These range from all types of feathers and down to wool filling. The tops are heat-generating, yet lightweight. This means that children will be able to keep hold of their body heat without feeling smothered. And as far as care is concerned, it couldn’t be simpler: throw them into the washing machine inside out and then straight into the tumble dryer. Emily Attwood, founder of sleep-brand scooms agrees, ''We’d always advise a 9 tog to 13.5 tog for the winter months as this is ideal and will keep you warm. If your house is always on the warmer side, then a 9 tog duvet would probably suit you better throughout the winter months, and you wouldn’t want to go any higher. This will prevent you from overheating which can disrupt your sleep.'

The North Face fleeces are a classic, and with good reason – they last for years and are thoughtfully designed. The newly-launched and well-priced TKA Glacier fleece is an easy choice if you’re after a versatile fleece you can wear in all seasons, and we love its retro styling.

What to consider when buying thermal socks

Buy it if: you're looking for luxury as well as warmth. No duvet fill feels quite as sumptuous as down, and this 90% Hungarian goose-down and 10% goose feather option is one of the best. It's super warm, drapes beautifully, and feels super luxurious. The all-seasons option also offers brilliant versatility; use the 4.5 and 9.0 duvets separately in warmer seasons and combine when the evenings start to drop in temperature to create 13.5 togs of winter warmth. Plus, although it's an investment, the all-seasons design means you'll also be kitted out with cooler tog duvets for spring, summer and autumn. They also come with a blister-free guarantee, because the inner layer stays with the foot and the outer layer moves with the shoe to reduce friction. It’s a clever system, although they do recommend sizing down to ensure as snug a fit as possible.

After much testing, we think 13.5 tog is best tog duvet for winter, with most of our testers finding 15 tog can retain heat a little too much during the night and lead to overheating. Although you can get duvets in almost any tog rating, the most common togs are 4.5 tog which makes a great summer duvet weight, 10.5 tog which tends to be the best bet for autumn and spring, and 13.5 tog which offers good winter warmth. There’s no doubt that these bottoms are one of the pricier options on this list, but in our opinion it’s well worth the extra cost. It works as intended, and with proper care will last an incredibly long time. The men’s bottoms here include a merino-covered elastic waistband and a standard fly design. Overall, Smartwool has some of the most comfortable and warm thermal underwear available.

Although it will mean spending a little more, and may depend on your bed frame height and style, we'd generally advise sizing up with your duvet, especially if you sleep with a partner.