Gear Review: 2019 ThermaRest Ultralight Sleeping Bags and Quilts
By Brad Brooks
ThermaRest has long been known for making some of the best lightweight sleeping pads on the market, and their new sleeping bags and quilts are finally on par with their pads in creating the ultimate backcountry hunting sleep system. I had a sneak peak at ThermaRest's lineup a year ago and after looking at the specs and design I had a feeling they would be knocking it out of the park.
I was also sent a sample of the ThermaRest Hyperion 20 Sleeping bag to use during the 2018 season. Now before I get too far, I should note that I am picky about my sleeping bags and quilts when backpack hunting. I've frozen my butt off too many times to count and I've become a skeptic of temperature ratings claimed by companies. So when I read ThermaRest's claim of a full mummy bag that weights barely over a pound for a 20 degree bag, I was skeptical.
But after putting the bag to use over the course of 3 different hunts that went into late October in Wyoming, I was sold.
Temperature ratings from some sleeping brands can be unbelievably off, and pretty much every person that has ever slept in a sleeping bag knows that. There are several reasons why, but and much of it has to due with marketing and different methods for testing those ratings.
ThermaRest is the only brand (seriously), that owns a cold chamber specifically for testing the ratings on their bags and sleeping pads. And the ratings on each bag are used to show the "comfort" zone, what temperatures you can sleep in and stay alive, and what temperatures at which any bag or quilt will not keep you warm.
The ratings on ThermaRest bags have all been rigorously tested in their cold chamber, and in my experience they are accurate.
The other thing that significantly impacts how warm you stay in your bag, is your sleeping pad. A lot of people, including me, underestimate how important this is.
What Makes the Hyperion and Vesper Lines Different
There are a few features that make the ThermaRest Hyperion and Vesper line of sleeping bags and quilts incredibly light and warm. In fact, the Hyperion and Vesper lines share several features in common that are important.
- Weight- The Hyperion 32 bag weighs 16 ounces, and the Vesper 32 degree quilt weighs 15 ounces. Those weights are simply incredible. Particularly for the Hyperion, it is in a class of its own for a full coverage mummy bag at 16 ounces.
- 900 Fill Hydrophobic Down-The down of any sleeping bag is what makes it function. The number associated with the down refers to the quality of the down. The higher the number the more loft the down has and the less weight it takes to retain your body heat. 900 fill down is premium quality and allows the bag to have a high loft without being heavy. Hydrophobic means the down is treated with a waterproof coating, which is really important for maintaining loft. As down gets wet, which can easily happen from body moisture evaporating during the night, the loft of the down will decrease, particularly on multi-night trips if the moisture doesn't escape from the down during the day. Having a waterproof treated down ensures the loft of your bag will remain, even as you evaporate moisture during the night.
- Radiant Reflective Heat-ThermaRest used a material on the inside of the sleeping bag that ads warmth by reflecting your body heat.
- Down Placement- Compressed down on your back does little keep you warm. In the Hyperion and Vesper, ThermaRest created sewn zones to keep down where it matters most for keeping you warm, like your torso, and to prevent "down migration", which happens over time as down tends to collect in certain parts of your bag.
- Packability-Because the Hyperion and Vesper bags use a 900 fill down, they will compress down to a significantly smaller size than lower quality down, such as a 700 or 800 fill down.
In addition to the features above, the Hyperion Sleeping bags have a few features that make them stand out as traditional mummy bags. There are some additional design features that ThermaRest used to make the Hyperion 20 and Hyperion 32 so incredibly light compared to other traditional sleeping bags.
- Half Length Zipper-the Hyperion has a 1/2 length zipper to cut down on zipper weight. This might seem like an insignificant feature, but I was concerned with how this could make getting into the bag harder. It did not make getting in and out awkward at all, and if anything made me wonder why there aren't more bags with half length zippers.
- Tapered Footbox-In order to cut some weight off the bag, ThermaRest designed the bag to have a slimmer leg fit, and a footbox that is angled to prevent your feet from compressing the down around your feet.
- Pad Attachment- Rolling off of your sleeping pad isn't something everyone has an issue with, but I do. The pad attachment system on the Hyperion definitely helped keep my bag glued to my pad during the night.
- Perimeter face baffling-When I want maximum warmth out of my bag being able to fully zip the mummy hood and have baffling that negates drafts without making you breathe into your bag is a nice feature.
When I first took the plunge in trying our quilts, I should have been more prepared for the small features that would have an outsized impact on how the quilt would function. Three years ago I was sent a quilt to field test by a company and I sent it back after a summer weekend trip and told them it was a horrible product and I wouldn't ever use it again.
Since then I've used a few different quilts, and I've learned what makes a mediocre quilt from a comfortable one, and where the weak points are. In addition to the high quality down and radiant reflective heat material on the inside of the quilts, there are a few other subtle but important features in the Vesper line.
- Perimeter Baffling-As you might imagine, cold air coming in from the sides of a quilt is where you will quickly know if a quilt is working as advertised. I haven't used another quilt that has a dedicated layer of down around the edge of the quilt designed to prevent drafts form coming in, and the perimeter baffling helps to create a seal between your body and your sleeping pad, which is key.
- Sewn Footbox-The sewn footbox helps to keep the quilt in place throughout the night, which also helps prevent drafting.
- Pad attachment- The pad attachment system in a quilt is key. You want a pad attachment system that doesn't have air gaps and allows drafts, and the single pad attachment on the Vesper does a good job of sealing out the cold air.
Quilt or Sleeping Bag?
Quilts are great for lightweight backpacking, and I have had great luck with them during the early season through mid October. I've also had some cold nights in some quilts, and my general recommendation to people is that quilts are great for archery season, but traditional zippered bags are best for most people when temperatures start to drop in October.
I won't get into an in depth piece here on the merits of quilts vs. sleeping bags, but I will be honest that a quilt is not for everyone. I personally like them in September and early October, but if you toss and turn a lot you could end up cold. And the pad attachment system is super important.
If you are worried about being cold, stick with a traditional sleeping bag. If you are a weight fanatic and don't mind being adventurous, I would definitely give a quilt a try.
How Does the Price Stack Up to the Competition?
I would encourage anyone to do their own homework on high end sleeping bags and quilts and compare the price, weight and reliability of the temperature ratings. As we previously discussed, not all temperature ratings are created equally. I think you will find that the price point for the Hyperion and Vesper is on the low end of the high-end sleeping bag market.
And specifically to the Hyperion, there are few bags that compare on weight and warmth, and none that compare at the same price.