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STAY WARM Sleepwear - Men's Long Sleeve

Keep warm without overheating. Created in partnership with Swiss sleepwear start-up Dagsmejan, our sleepwear combines super-fine merino wool and high-tech Tencel® for exceptional comfort and breathability. Extremely soft and luxurious to the touch, this blend of nature's best-performing fibers takes your PJs to a new degree of comfort.


Dark Grey

Size View Size Guide
Small 35" - 37"
Medium 37" - 39"
Large 40" - 42"
Extra Large 42" - 44"
Small 29" - 31”
Medium 32" - 33”
Large 34" - 36”
Extra Large 36" - 38”

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Free Shipping

60 Night Trial


Additional Details

Engineered to offer lightweight warmth. Luxury merino wool for comfort and Tencel®, nature’s high tech fiber from eucalyptus, for breathable softness. Tested against fabrics such as cotton, bamboo, and synthetics, NATTWARM™ is more warm than textiles up to 50% heavier while allowing superior breathability.

NATTWARM™ fabric allows for breathable warmth in a featherweight package

50% lighter than cotton with comparable warmth properties

Oeko-Tex Standard 100 Certified Technology

Why we're different.

As part of our B.E.T.A program to develop the most innovative sleep products, we've partnered with Swiss sleepwear start-up Dagsmejan to launch a line of light, warm sleepwear.

Extremely soft, luxurious to the touch, and featherweight, this blend of super-fine merino wool and high-tech Tencel® provides exceptional warmth, comfort and breathability.

NATTWARM™ fabric allows for breathable warmth in a featherweight package 50% lighter than classic cotton with comparable warmth properties 2x softer than cotton Tagless design with flat, ergonomically placed seams Easy to care for – just throw it in the washing machine

We pass on everything we learn to our customers. From sleep studies to new technologies, we want to help you make informed decisions about your sleep.

Click to learn more about our studies: Heat Sleep Study Humidity Sleep Study

The thoughtfulness is in the details.

It doesn’t stop at thread count. It’s the little things, the thoughtful details, that make our products the best available.

Tagless Design

Tagless design with flat, ergonomically placed seams

Maximum Comfort

Specially cut for maximum comfort

Easy to Care For

Just throw it in your home washing machine

Most frequently asked questions.

How do I wash my sleepwear?

To wash your sleepwear, please follow the washing instructions on the tags. If you have cut your tags after purchase, then it is recommended to wash with Slumber Cloud Free & Clear Laundry Detergent or a mild detergent in cold water on a delicate spin cycle. When it’s time to dry your sleepwear, please dry on low heat or air dry. Do not iron your sleepwear. To reduce wrinkling, take your sleepwear out of the dryer and immediately place it on your bed or use a wrinkle release spray such as Iron In a Bottle for that crisp and finished look.

Does Free Shipping Apply To International Orders?

Free shipping is only valid for US and Armed Forces delivery addresses. However, we do offer discounted shipping rates to Canada addresses.

Do you ship internationally?

Currently, we only ship internationally to Canada. At the time of purchase we include the cost of shipping, taxes, and duties for Canadian shipments. No additional fees will incur at delivery, but if they do please contact our customer service team at to take care of the issue. For all other countries, if you find a forwarder or have a friend or family member here in the states, we would be more than happy to work with you to get it there.

Can I still return an item even if it's been washed?

We accept returns in any condition within 60 days of purchase! We want you to absolutely love your new bedding, so if you wash an item, try it out, and decide it's just not for you, we can definitely still initiate a return. Please note we do our very best to donate all returns to local charities instead of a landfill. We appreciate your help in this process by washing any used items before returning them to us.

Are shipping fees covered for returns?

All shipping fees for domestic returns are completely free! When you initiate a return through our returns platform, you will receive a prepaid shipping label to get the item back to us. If you live outside the US and are looking to initiate a return, please check out the return policy in the International FAQs.

How do I initiate a return?

If you're looking to initiate a return, just head over to our returns page! Please note that we are not able to process returns for items listed as Final Sale or past the 60 day return period.

What is your return policy?

Bedding: All bedding products, excluding “Final Sale” items, come with a 60-Day Satisfaction Guarantee. Sleep on it, wash it, and really test it out - If you are not fully satisfied with your new bedding you can return the item(s) within 60 days of your purchase date, no questions asked. A refund will be issued, within 7 business days of receiving the returned product.

Final Sale: Final Sale are not eligible for return, exchange, or the 60 night trial period.

Apparel & Home: Items in new and unopened condition are eligible for a return or exchange within 60 days of purchase. In the event of a return or exchange, our team will inspect the item and if determined it is new, a refund or exchange will be issued within 7 business days of receipt. If the item is in used condition, missing tags, or has been removed from the packaging, the return or exchange will be voided and the product donated to a local charity.

Are your products covered by a warranty?

Yes! All of our products are covered not only by the 60 night trial period but also a 180 day warranty which covers manufacturers defects (i.e. stitching, sizing). Please note in addition to damage caused by disregard of care instructions, temperature performance is not considered a manufacturers defect or covered by the product warranty.

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Free Shipping & Returns

All U.S. orders are shipped right to your door, free of charge.

Try it For 60 Nights

Sleep on it, wash it, and really put it to the test for two whole months! If you don’t love your new bedding, just return it for a full refund. No questions asked!