VBL for generally sweaty people

“I was wondering if it is worth trying VBL in weather that is not necessarily freezing?”

Have you read this?

Generally, it’s my understanding that VBL’s aren’t recommended for temps above freezing. If you are sweating, I’d probably suggest working on creating a system for improved thermal regulation prior and up to getting in your sleeping bag.

Sweating in a sleeping bag sucks, it creates unwanted convection (as you obviously know), and it’s basically a kiss of death in freezing temps. It may be good to slow down a little or dump some heat before getting into your bag, and make sure you are wearing a full wicking layer first and foremost. I’ve found that even in the hot/humid nights of summer mid-Atlantic backpacking, I’m significantly more comfortable in a full wicking layer. (and a small air pillow to keep my legs from touching eachother since I’m a side sleeper.)

Remember: better sleep comes for most of us by being more comfortable. Heat, humidity, sound, light, pad firmness, and what’s in your belly & bladder…

All these will very much affect comfort in different ways, and each one of us probably respond differently to these variables. It’s good for me to develop an awareness of what I am most sensitive to, and work toward managing that fist and foremost.

Tape together a few cut trash bags and see if it works for you.

As other have indicated.  VB above freezing is generally not useful. As to sweating at night … Generally people don’t sweat unless they are too warm, or hyper-stressed.  A small percent of the population suffers from hyperhidrosis … e.g. excess sweating.  If this is you, a VB will just make it more unpleasant.  There are a variety of causes / treatments for hyperhidrosis…you might want to talk with your doctor.

–mark

An oft overlooked consideration that you might want to experiment with is decreasing the amount of protein in your evening meal.  Protein metabolism has a thermic effect of 20-30%, in comparison to 5-15% for carbs and fats.  This translates directly into heat released from the digestive processes and hence from your body via sweating.  At night this can be either beneficial or detrimental, depending on the individual.  For instance, in my case, I purposely load up on protein at night to add a little extra warmth to my sleeping bag.  But then, I do not sweat excessively.  In your case, more protein might exacerbate your problem.  I don’t know, but it might be worth doing a little experimenting to see if you can reduce your sweating a little by reducing the protein in your evening meal.  I don’t think it would solve the problem entirely, but every little bit helps.  Below is a link to a brief description of the concept and how the 3 classes of macro nutrients vary in their thermic effect.  There is a lot more information in their reference list should you want to dig deeper.

https://en.wikipedia.org/wiki/Specific_dynamic_action

1. As others have already said, a VBL is not going to be comfortable above freezing.

2. If temperatures get into the 30’s and your bag has a comfort rating (upper rating) of 45…..for a cold sleeper your bag is probably not warm enough.  See this explanation for the ratings:https://www.rei.com/blog/camp/understanding-sleeping-bag-temperature-ratings

You can always open your bag up a bit, if it is initially too warm.  Also, be sure to wait until you’ve had a time to relax and cool down before jumping in the bag.  Just relax and enjoy the scenery for a bit :) Also, make sure that you change absolutely everything…….especially underwear and other undergarments.  This will give you a feeling of true dryness and also don’t change into them until you’ve cooled down.

3. Personally, I feel the most dry and warm by wearing the thinnest wool long underwear and long sleeve top (120-150 grams) and supplementing warm layers on  top if needed.  I also can sleep a bit sweaty and wool makes me feel much dryer than nylon or polyester “wicking layers”……since wool is more breathable than these materials and wool actually absorbs a bit of the moisture, unlike the above artificial materials.

4. Another thing, is that if you go to a warmer bag, you won’t have to consistently wear a puffy which will also cut down on sweating.  An extra 2 not so breathable nylon layers from the puffy also is going to make you more likely to sweat.

VBLs are always warmer than breathable bags, including shoulder seasons and the summer.

I always use a vapor barrier (Cuben fiber/Dynema composite) because my bags are made of vapor barrier material.  Even my summer bag.

Yes, insensible perspiration, mostly from my feet, wets the inside of the footbox.  It’s not a problem, I don’t find it to be clammy or sticky.  I sleep well and wipe up and dry out the footbox as needed.  I don’t mind that a little wetness collects inside because it is easy to manage, and the vapor has no way to accumulate in the down.