Slumber Sack, Baby Sleep Bag with Sleeves, Merino Wool & Organic Cotton, Goose

• Premium Natural Fabrics – Made with Australian superfine merino wool lining (260gsm) and organic cotton outer, this baby sleep sack with sleeves provides extra warmth for cooler nights while staying gentle on delicate skin.

• Ideal for Cooler Rooms (60–70°F) – Designed for comfortable sleep in cooler temperatures, the slightly heavier merino wool lining and sleeves provide added warmth without overheating.

• Natural Temperature Regulation – Merino wool naturally regulates body temperature, keeping your baby warm when it’s cool and comfortable when temperatures rise, for balanced sleep throughout the night.

• Breathable & Moisture-Wicking – This merino wool sleep sack helps prevent overheating by allowing airflow and wicking moisture away from the skin, keeping your baby dry and cozy.

• Sleeves for Extra Warmth – Built-in sleeves provide additional coverage for cooler environments, and allow freedom of movement during sleep.

• Easy Diaper Changes – A convenient two-way zipper makes dressing and nighttime diaper changes quick and easy. Zipper guards protect your baby’s skin and help discourage your baby from chewing on the zipper pull.

• Certified Safe & Non-Toxic – OEKO-TEX® STANDARD 100 certified (23.HUS.59156, Hohenstein HTTI), tested against harmful substances for your baby’s safety.

• Responsibly Sourced Materials – Made with Woolmark® and RWS-certified merino wool (cruelty-free, mulesing-free) and GOTS-certified organic cotton.

• A safer alternative to loose blankets
  Helps your baby stay covered through the night, replaces loose blankets in the crib, and promotes back sleeping.

Free shipping in the USA (Expected Delivery: 3-6 Business Days) on orders of $95 USD or more.

VIP Shipping: Your order is processed within 1 business day, even during high-volume periods. Enjoy faster delivery (estimated 2–4 business days) for a flat rate of $10 USD, available at checkout.

Express international shipping (Expected Delivery: 2-5 business days) starting at $14.99 USD.

Easy returns within 60 days* of purchase.

Additional information about our shipping policy can be found here.

Machine wash on low (100°F max), use wool or mild detergent. Close zipper. Can be tumble dried on No Heat or Air Dry setting. Hang to dry whenever possible. To refresh and reduce washing, turn garment inside-out and air often.

We do not recommend sizing up. The sleep bag should be well-fitted around your child's upper body for a safe and secure fit. We recommend using our sizing guidelines to determine the correct size based on your child's age, height, and weight. Your baby should not be below the minimum recommended weight.

• Setting the standard for textile safety, from yarn to finished product, Woolino sleep sacks and clothing bearing the OEKO-TEX® STANDARD 100 label (23.HUS.59156, Hohenstein HTTI) have passed safety tests for the presence of over 1000 harmful substances;
• Woolmark® and RWS certified merino wool (Responsible Wool Standard - cruelty-free, mulesing-free wool); 
• GOTS certified organic cotton.

What room temperature is the Slumber Sack best for?

The Slumber Sack is ideal for cooler room temperatures between 60 - 70°F (16 - 21°C). It provides cozy warmth without overheating, helping your baby sleep comfortably throughout the night.

Will my baby overheat in a merino wool sleep sack?

Merino wool naturally regulates temperature, releasing excess heat when it’s warm and insulating when it’s cooler, so your baby stays comfortable, not overheated.

What should my baby wear under the Slumber Sack?

We recommend lightweight, breathable sleepwear made from natural fiber, like cotton or merino wool. You can adjust layers based on room temperature. 

What makes the Woolino Slumber Sack different from other sleep sacks?

Made from premium superfine merino wool and organic cotton, it naturally regulates body temperature, wicks away moisture, and provides breathable comfort through the night. What’s more, merino wool retains its warming properties even when wet. The sleeves and slightly heavier merino lining make it ideal for cooler room temperatures (60–70°F).

Is the Slumber Sack safe for sleep?

Yes. It’s designed as a wearable blanket to replace loose crib blankets, supporting safe sleep recommendations and giving you peace of mind.

Is merino wool safe for sensitive baby skin?

Yes. We use superfine merino wool that feels soft against your delicate baby’s skin. It’s uniquely breathable, gentle, and well-suited for sensitive skin, helping maintain a comfortable sleep environment night after night.

What are the benefits of merino wool in a baby sleep sack?

Merino wool helps regulate body temperature, wicks moisture away from the skin, and stays breathable throughout the night. It also continues to insulate even if damp, supporting a consistently comfortable sleep for your baby.

How can I tell if my baby is too hot or too cold?

The best way is to check your baby’s chest, tummy, or the back of their neck. Hands and feet can feel cooler and aren’t always a reliable indicator of overall comfort.

How do I care for my Woolino Slumber Sack?

Merino wool naturally resists odors and doesn’t need frequent washing. When needed, machine wash on cold with a mild detergent, and air dry or tumble dry on No Heat setting.

Is the Woolino Slumber Sack certified safe and responsibly made?

Yes. It’s made with OEKO-TEX® STANDARD 100 certified materials, Woolmark® and RWS-certified merino wool, and GOTS-certified organic cotton—so you can feel confident in both safety and quality.