Sleeping bag liners

[TwoSpirits]

Whenever I see any YouTube hikers prepping for an early start, it seems many of them say they are bringing a sleeping bag liner (usually the Sea-to-Summit Reactor) because "they say it can add, like, 20° more warmth to my bag (or quilt.)" Yet I never hear anyone ever follow-up and say whether or not that has truly been their experience. Any hikers who do a post-hike gear review will say they used and loved their sleeping bag liner because it kept their bag cleaner, but those are the lightweight "travel" ones.

I'm genuinely curious if anyone can share their experience with these Reactor liners, and especially if they think it's worth the weight and [considerable] expense. It looks like these things range from 8 to 14 ounces, and cost $60 to $70.

I'm not considering one, just curious.

[nsherry61]

I have all kinds of opinions on them.
1) Yeah, they're expensive
2) They're heavy for the amount of insulation they provide relative a sleeping bag or quilt that has that much more insulation included in it.
3) Although they do increase your sleep systems overall warmth, the amount of added warmth claimed is way out of line with reality.
4) They are soft and some people may prefer the feel of a reactor liner to the sticky nylon of their sleeping bag's inside material.
5) You will get much more added warmth per weight to you sleep system by adding an additional quilt to the top than you will by adding a reactor liner to your bag.
6) A wet Reactor liner surely holds its small amount of insulating value better than most bag or quilt insulation material when it gets wet . . . so keep your gear dry.
7) Reactor liners come in fun colors, but sadly, only one choice per model.
8) A reactor liner is probably more comfortable to sleep in on an 80 degree night than a sleeping bag.

[HankIV]

I am considering one and would be interested as well.

I did use a lighter weight one a couple summers ago. Worked to keep bag clean, and was nice on a couple of warmer nights when even my 50F bag was too warm.

But am not sure what the added warmth is.

[CalebJ]

A sleeping bag liner as a way to simplify keeping your bag clean isn't a bad option. But if you're just trying to sleep warmer, consider adjusting what you wear and what you eat before you crawl into bed. Or a warmer bag.

[Slugg]

I use one of these 'Western Mountaineering Sonora' liners and I'm a fan:
https://www.backcountry.com/western-...ping-bag-liner

Here are my thoughts:
It weighs in at just under 5 oz
It's current price made me grimace a bit - I paid roughly double that 3 years ago
20 degrees warmer is significantly more than my experience. I would say more like 5 degrees if I had to quantify it like that, but that's not why I use one.
I use a quilt, so the liner creates a "barrier" between myself and the pad, tent floor, air, etc where the quilt allows small "holes".
I use a regular-width TAR X-Lite, and the bag helps me keep my elbows and limbs on a relatively "narrow" pad
In the summer, I typically fall asleep in my liner only, on top of my quilt.
The cleanliness factor is great - just throw the liner in the washing machine - extends the life and effectiveness of a down quilt by keeping it clean(er)

[Slo-go'en]

My sleeping bag seems to be cut for someone much larger around then me. Using a silk liner helps fill up some of that extra space and reduces drafts. It's not quite warm enough to be used by it's self. When it's really hot, I will often start out with just the liner, but at some point it gets colds enough to pull the sleeping bag over me.

While the silk liner doesn't add as much extra insulation as one of the Reactors would, it adds just enough to extend the range of my summer bag into late spring and early fall without adding much weight or bulk. The main problem is getting in and out of them!

[ScottTrip]

I started the AT in early March and did have a liner to add some warmth to my 20 bag. The temps several nights were in the single digits and my sea-to-summit liner was a welcome addition. I did send it back home in April and but got it back in New Hampshire for the final miles and glad I did with some evening temps in the teens. The comfort was well worth the small amount of additional weight.

[Tipi Walter]

A bag liner is just one more item to cause claustrophobia in a zipped up mummy bag.

Here's one example: You're zipped up tight on a cold night. You toss and turn all night. Your face ends up in the bag's hood so you have a difficult time finding the bag zipper to get out. Now compound this problem by being inside a liner plus a zipped up bag---and trying to pull an arm up out of the liner to find the bag's zipper---which is now behind your head or neck.

This cocooning problem can be solved easily by getting a stand alone bag rated to 0F or subzero temps. My winter bag, rated to -15F, can take me from -15F to 50F---from zipped up mummy config to unzipped throw-over quilt.

[TwoSpirits]

The claustrophobia factor is the reason I've never really considered getting one. The idea of sleeping in a potato sack inside a sleeping bag just didn't sound appealing. I did, however, score a Western Mountaineering Everlite a couple years ago, and that has been an awesome addition to my sleeping bag livery. Fantastic by itself in summer, and when I use it in conjunction with my Sycamore it really does extend the range from 25° down into the teens.

[Time Zone]

If you search well, I think you'll find some old thread where someone reported back testing results using an IR thermometer or something fancy like that. It's pretty much as others indicated: claimed temp increases are about double reality, at best. maybe 4x higher than reality at worst.

I'd also reiterate other comments: in cooler weather, it's easy to get tangled up in them. Better to wear the equivalent in warmer sleepwear - let the sleepwear be your liner. In warm weather, when you may not be covered head to toe in sleepwear, they can be nice for keeping your bag cleaner, so you don't have to wash it as often. In hot weather, they may suffice alone, or with a light top quilt or throw.

I have a cheapie polyester one that replaced a too-heavy one I made from a twin bed flat sheet (my first sewing adventure). The cheapie is under just under 11 oz and under 1 L when rolled up. It's rectangular - else could be smaller/lighter. But it does get use in warm weather.

[RangerZ]

Not claustrophobic but it’s hard to shimmy into a liner inside of a sleeping bag. I don’t shimmy well.

[Alligator]

I agree as well with Tipi Walter. I had a fleece one that probably added about 10F, but it was heavy and got tangled a lot. Blanket pins are big safety pins that might help but it depends on how much you twist. I never tried one with a quilt so that does have potential to eliminate some drafts while being easy to get into. I found that a new bag with a chest baffle was a better option at the temps I was using mine.

[Leo L.]

I've used two bag liners in the past, a silk one inside the bag to give a cosy feeling on the skin, and a nylon one outside to keep the wind off.
The nylon one outside might have added a few degrees of warmth in really edgy conditions, I wouldn't claim any warmth bonus for the silk one inside.
One idea behind this two-liners-system was, to have the possibility to just use the two liners, the silk one inside the nylon one, when cowboy camping in really warm nights to keep me safe from insects.
In reality, this never worked as expected.

At some point I got fed up about this complicated sleep system and all the different zippers and chords to pull, and just changed to:
- a set of long-sleeved Merino underwear I wear for sleeping exclusivly (but consider as a backup if the main clothes got soaked)
- a balaclava, to protect my bald head and to keep the cape of the sleeping bag clean
- a decent sleeping bag thats fit for the temperature range I'd expect on a given hike (as I'm getting older, I tend to overshoot the rating a bit to make sure I'll never get cold)
- if its really cold, like in the cold snap we had here the past few days, I take two of my sleeping bags one inside the other - which worked really fine during my most recent winter hike.
All sleeping bags I own have a right-hand zipper so its reasonably easy to close&open the bags.
- as a backup, I usually carry a down jacket which I can spread atop of the sleeping bag if I get hit by an unexpected cold. This really helps a lot!

[ldsailor]

I started doing LASH's of the AT in 2016. As clueless as I was, I bought a 30 degree rectangular synthetic sleeping bag when I started out in April. I froze. I bought a Sea to Summit Reactor liner at Mountain Crossings for about $70. It saved me. However, I would estimate it only added about 10 degrees warmth to the bag. I still slept in most of my clothes.

After that, I got smart and bought a down 30 degree mummy bag and hiked in warmer weather. Last year, I bought a REI 15 degree bag for the Colorado Trail and it worked out great. It can get pretty cold at 10,000 to 12,000 feet, but the sleeping bag kept me warm. I never slept in my hiking clothes - usually just shorts and a t-shirt.

I have never used the liner again since the first LASH on the AT. Get a warmer bag. My REI 15 degree bag is as light as my 30 degree bag, so why would I need a liner?