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What you put under a merino sleep sack depends on the room temperature and how warm your baby feels - not just on the season. On most nights, a long-sleeved romper or bodysuit is enough. Feel the neck or the area between the shoulder blades. Hands and feet may feel cooler; that says little about the temperature of the torso. Why the base layer matters Cotton and synthetic sleep sacks often have a TOG rating: a fixed number indicating how much warmth the fabric retains. Our Merinowool sleep sacks do not have a tested TOG rating on the label. Merinowool works differently: the fiber holds air when it gets cooler and helps release heat and moisture when your baby gets warmer. As a result, you usually adjust what your baby wears underneath instead of immediately looking for a different seasonal sleep sack. Keep an eye on both the room and your baby - especially on warm nights. Read more about TOG in TOG ratings for baby sleep sacks. How do you know if it is right? Slide your hand into the neck area, between the shoulder blades, under the clothing. Comfortably warm and dry: usually just right. Damp or sweaty: remove one layer. Clearly cool: add one layer. Babies’ hands and feet are often cooler because of their circulation - even when the torso feels perfectly comfortable. The neck or chest gives a more reliable indication. Read more about signs that your baby is too warm or too cold: How do you know if your baby is too warm or too cold? What should your baby wear under our sleep sack? The Moalie merino sleep sack is sleeveless. That is why we recommend a long-sleeved romper or bodysuit underneath on the product page. Start with one suitable layer, then adjust if the room or your baby calls for it. Every baby responds differently, and bedrooms often cool down during the night. Preferably measure the room at the height of the cot mattress. Cooler room. A wool romper or long-sleeved merino bodysuit under the sleep sack. If the neck feels cool, you can add one thin layer - for example, trousers - and check again. Do not place a loose blanket over the sleep sack; adjust the base layer instead. Mild, comfortable room. The same long-sleeved romper or bodysuit is usually sufficient. With merino, you mainly adjust what your baby wears underneath. Warmer night. A thinner romper or bodysuit. Feel the neck again later in the evening; warmth sometimes builds up only later. Very warm night. Dress your baby more lightly under the sleep sack - sometimes just a nappy - and check more frequently. In extreme heat, some parents leave out the sleep sack for a while; follow what works for your family and the safe-sleeping guidelines from your child health clinic. For sleepsuits and broader guidance by temperature: Sleep sack, sleepsuit, or both? That article covers more products; here we are focusing on the base layer under our merino sleep sack. What parents often wonder about Cold feet. Normal for many babies. Check the neck or the area between the shoulder blades first. A blanket over the sleep sack. A sleep sack is designed to make loose blankets unnecessary. Follow the safe-sleeping guidelines from JGZ and your child health clinic: a suitable base layer is preferable to a loose blanket over the top. A second sleep sack. Handy for laundry. For temperature regulation, adjusting the base layer is often enough with merino. A different model may suit your routine, but that is not the same as automatically needing both a summer and a winter sleep sack. Romper under the sleep sack The first layer touches the skin. A soft wool romper or long-sleeved bodysuit is comfortable under a sleeveless sleep sack and makes it easy to add or remove one layer. At Moalie, you will find wool rompers (including merino-bamboo and merino-cashmere bodysuits) and the Merinowool baby sleep sack with a teddy texture: 100% Merinowool, made in the EU, without a TOG label. Choose a size that fits - not one to grow into - so the neck opening remains safe. Frequently asked questions Do I need a separate summer and winter sleep sack with merino? Usually not for temperature regulation. A second one can be practical for laundry. In hot weather, dress your baby more lightly under the sleep sack. What TOG rating does a Moalie merino sleep sack have? There is no tested TOG rating on the label. See also our TOG article. In conclusion Explore our Merinowool sleep sacks and the wool rompers that fit underneath.

Many parents hesitate between a sheepskin and a wool liner. They look similar but differ significantly in safety, texture, and use — even in warm weather. Daniëlle explains it calmly.

Premature and dysmature babies have one thing in common: they need extra help with temperature regulation. As a neonatal nurse, I explain the difference between the two groups, why warmth is so crucial for their development, and how merino wool and layering can help. This includes scientific evidence and practical tips for a safe, warm start.

Merino wool helps babies sleep better — scientifically proven. Studies from The Lancet, the British Journal of Dermatology and the University of Sydney show that merino wool leads to faster sleep onset, longer sleep, less itching and better temperature regulation. Discover why more and more parents are choosing merino wool.

Merino wool isn’t just for winter – it’s a smart choice for your baby in summer. Merino wool actively wicks away heat and moisture, keeping your little one cool and comfortable, even on the hottest days. In this blog, you’ll learn how merino wool works, why acrylic and synthetic fabrics are less suitable for warm days, and why more and more parents are choosing Merino by Moalie.