Cosy and Safe Sleep with 3.5 TOG Winter Sleeping Bags

When temperatures drop, your baby needs a warm, breathable sleep environment. Slumbersac’s 3.5 TOG winter sleeping bags are specially designed to keep your child snug without the risk of overheating. Whether you choose a classic sleeping bag or a style with feet, each bag offers cosy warmth while allowing air to circulate.

Made from 100% cotton on the inside and out, and lined with breathable polyester fleece, these sleeping bags feel soft on delicate skin and help maintain a comfortable temperature throughout the night. Despite their thick insulation, they remain lightweight - allowing your baby to move and sleep soundly.

Choose from styles with or without detachable sleeves, depending on your little one’s needs. Sleeveless options can be paired with separately available sleeves for added flexibility.

What Makes a 3.5 TOG Sleeping Bag Ideal for Winter?

TOG is a British standard used to measure the warmth of textiles. A 3.5 TOG sleeping bag is suitable for cold rooms under 18°C, making it the best choice for winter use. If your baby’s hands and feet feel cool at night, it’s not a cause for concern - check their temperature at the back of the neck instead to ensure they’re warm but not sweaty.

Learn more in our TOG Guide.

Finding the Right Size

Slumbersac offers sleeping bags in six sizes, suitable for newborns up to 10 years. Your baby should be able to kick and wriggle freely, with their feet sitting around three-quarters down the bag.

For safety, the neckline should fit snugly - just enough room to slip a finger between the fabric and your baby’s neck - and armholes should prevent slipping or heat loss. Up to 36 months, press studs on the armholes provide a secure fit.

Use our Size Guide to find the best fit. Footed sleeping bags are generously sized, so there's no need to size up.

Why Choose Slumbersac?

  • Wide range of designs, sizes and TOG ratings
  • Made from 100% cotton – gentle on sensitive skin
  • Oeko-Tex Standard 100 certified – free from harmful substances
  • Machine washable and tumble dryer friendly
  • Friendly UK customer service team ready to help

Still unsure which sleeping bag is right for your child? Contact our team – we’re happy to help.