Updated 09/01/2026

My favorite baselayers for sleeping, camping, and layering in cold weather, including merino wool, alpaca, and synthetic options in a range of weights.

Baselayers are the foundation of a layering system, adding warmth while helping manage moisture. I use a range of fabrics and weights depending on the conditions and how I’m using them, from lightweight layers for sleeping to warmer options for colder weather.

I primarily use baselayers as sleep layers when backpacking and camping, bringing a clean, dry set to change into at night. Changing out of the clothes I’ve worn during the day keeps sweat, dirt, and body oils away from my sleeping bag and gives me a fresh layer for sleeping. I also use these layers for extra warmth around camp when temperatures drop.

While some people wear baselayer bottoms under pants for hiking in cold weather, I generally don’t because I tend to overheat, and removing them while hiking isn’t always practical. Instead, I wear heavier-weight pants for hiking. For tops, I use a combination of lightweight layers that I can add or remove as my activity level and the weather change. See my post on What to Wear for Cold Weather Hiking for more on my approach.

Below are my favorite baselayer tops and bottoms, with options for different conditions.

Ultralight Baselayers

For backpacking, I prefer to keep my pack weight as low as possible so I focus on layers that have a high warmth-to-weight ratio. These options are as light as you can get, and provide a high level of warmth in spite of their low weight.

Alpine Fit Fastpacker Alpha 90 Fleece Hoodie: This hoodie is made with Polartec Alpha Direct fabric, which provides excellent warmth for its weight, breathability, and fast-drying performance. While it’s meant to be a mid-layer for hiking, I especially like it as a sleeping layer because it’s soft and warmer than most options, making it a versatile piece that serves two purposes.

• sizes available: XS to XXL
• fabric: 90gsm Polartec Alpha™ Direct
• fabric content: 78% recycled polyester, 22% polyester
• features: elastic binding on hood, cuffs, and hem
• weight: 3.9 oz (women’s small)

Farpointe TecnoWool Camp Pants: TecnoWool is similar to Alpha Direct fabric, but add wool for more warmth and better odor control. These camp pants are roomy for extra comfort and can be worn around camp as well as for sleeping in.

• sizes available: S to XL
• fabric: 120gsm Pontetorto TecnoCore 120gsm
• fabric content: 56% Polyester/ 44% Wool
• weight: 4.3 oz (size small)

Farpointe Alpha Direct Camp Socks: These camp socks weigh less than an ounce, and they keep my feet warmer than regular socks when I’m sleeping due to the insulation and roomy fit. Typical hiking socks have a tighter fit, which tends to make my feet cold at night, so I switched to these for better warmth, breathability and comfort. Note that these socks are not meant to be worn while hiking.

• sizes available: small (up to men’s size 10); large (up to men’s size 13)
• fabric: 90gsm Polartec Alpha Direct
• features: elastic binding on cuffs
• weight: 0.8 oz (size small)

Merino Wool Baselayers

Icebreaker Merino 200 Oasis Baselayer Top: Made of soft merino wool, this baselayer top feels more like a soft cotton tee than traditional wool. I’ve been wearing it on trips for ten years, and it’s still in great condition. Design features include underarm gussets and set-in sleeves for added mobility, while offset shoulder seams and flatlock stitching help prevent chafing. The droptail hem provides a little extra coverage.

• sizes available: XS to 3XL
• fabric: merino jersey fabric

Icebreaker Merino 200 Oasis Baselayer Bottoms: Made from the same soft merino wool as the top, these baselayer bottoms have a comfortable, non-clingy fit with a brushed elastic waistband and flatlock seams.

• sizes available: XS to 3XL
• fabric: merino jersey fabric

Heavyweight Merino Wool Baselayers

Woolx Baselayers: Warmer baselayers are essential for cold-weather trips, and these merino wool pieces from Woolx are seriously warm — especially good options if you tend to run cold. They’re thicker than standard merino baselayers, which typically use 120-gram fabric: the Hannah top is made with midweight 230-gram merino wool, while the Stella leggings use heavyweight 330-gram merino wool. I use these mostly for winter camping trips when temperatures are colder.

See my full review of Woolx Baselayers

Hannah Long Sleeve Top: The Hannah crew neck top is soft and comfortable to wear, with princess seams on the sides for shaping. Some wool layers can feel scratchy but I haven’t experienced that with this top. I would prefer a slightly shorter length for when I need to tuck this top into hiking pants but I like the length when wearing with leggings.

• sizes available: XS to 3XL
• fabric: 230-gram 100% Australian Merino Wool

Duralite Stella Petite Leggings: These leggings have a close-to-the-body fit without feeling tight or overly compressive, which is important to me since I don’t like a lot of compression. With only 3% spandex, they hold their shape without sagging, while the wide waistband is comfortable and doesn’t bind at the waist. Overall, I really like how comfortable these are. They look good too — the seams on the back add a bit of shaping and style.

• sizes available: XS to 3X in regular, tall and petite
• fabric: 330-gram heavyweight 85% Australian Merino Wool, 12% Nylon, 3% Spandex

Baselayer Bottom Options

Smartwool Classic Thermal Merino Baselayer Bottoms:  These Smartwool baselayer bottoms offer cozy warmth with a soft merino wool feel and a classic, easy-to-layer style that are comfortable for all types of cold-weather adventures.

Patagonia Capilene Midweight Bottoms: Made from 100% recycled polyester, these baselayer bottoms include wide waistband for comfort, and heat-trapping grid fleece on the inside. I frequently wear these as a sleep layer on colder overnight trips. 

Outdoor Vitals Highline Thermal Leggings: I recently purchased these men’s synthetic baselayer bottoms for backpacking trips thanks to their impressive warmth-to-weight ratio. At just 3.4 ounces, they feature a soft, brushed interior and a gusseted crotch for added comfort — and in spite of being a men’s fit, I find them comfortable to wear. I wear an XS size, which fits me well.

Gear Reviews: My goal is to share clear, unbiased information about outdoor gear. I am not sponsored by any gear companies and I don’t accept paid posts or links. I regularly receive products from brands for review, with no expectation of a positive review and no compensation for my opinions. As an independent gear reviewer, I only review items I’ve personally used on multiple trips and that I believe are high-quality and worth recommending.

Affiliate Links: I Heart Pacific Northwest is a participant in affiliate link programs which provide a small commission if a purchase is made through gear links on this site (at no additional cost to you). Thank you for supporting this website!