Therm-a-Rest offers a completely different type of sleeping bags in the Fast, Light series, designed for high-paced adventures and lighter than ever before. With the Hyperion -6 °C, you can brave the cold and sleep well, even in the mountains. The 900-cuin Nikwax Hydrophobic Down remains dry and retains its fluffiness up to sixty times longer than untreated down. It absorbs 90% less moisture and dries three times faster than untreated down. Free from harmful PFCs. Synergy Link Connectors attach the sleeping bag to a mat for optimal efficiency and comfort. The connectors can be removed. The Therma Capture lining traps body heat and keeps you warm without excessive bulk or weight.
Therm-a-Rest offers a completely different type of sleeping bags in the Fast, Light series, designed for high-paced adventures and lighter than ever before. With the Hyperion -6 °C, you can brave the cold and sleep well, even in the mountains. The 900-cuin Nikwax Hydrophobic Down remains dry and retains its fluffiness up to sixty times longer than untreated down. It absorbs 90% less moisture and dries three times faster than untreated down. Free from harmful PFCs. Synergy Link Connectors attach the sleeping bag to a mat for optimal efficiency and comfort. The connectors can be removed. The Therma Capture lining traps body heat and keeps you warm without excessive bulk or weight.
Therm-a-Rest offers a completely different type of sleeping bags in the Fast, Light series, designed for high-paced adventures and lighter than ever before. With the Hyperion -6 °C, you can brave the cold and sleep well, even in the mountains. The 900-cuin Nikwax Hydrophobic Down remains dry and retains its fluffiness up to sixty times longer than untreated down. It absorbs 90% less moisture and dries three times faster than untreated down. Free from harmful PFCs. Synergy Link Connectors attach the sleeping bag to a mat for optimal efficiency and comfort. The connectors can be removed. The Therma Capture lining traps body heat and keeps you warm without excessive bulk or weight.
Therm-a-Rest offers a completely different type of sleeping bags in the Fast, Light series, designed for high-paced adventures and lighter than ever before. With the Hyperion -6 °C, you can brave the cold and sleep well, even in the mountains. The 900-cuin Nikwax Hydrophobic Down remains dry and retains its fluffiness up to sixty times longer than untreated down. It absorbs 90% less moisture and dries three times faster than untreated down. Free from harmful PFCs. Synergy Link Connectors attach the sleeping bag to a mat for optimal efficiency and comfort. The connectors can be removed. The Therma Capture lining traps body heat and keeps you warm without excessive bulk or weight.
Last updated at 06/08/2026 00:00:39
Therm-a-Rest Hyperion 20F/-6C Ultralight Down Mummy Sleeping Bag
Affiliate Disclosure: We may receive a small commission for purchases made through this link at no extra cost to you. This helps support our site. Thank you!
Therm-a-Rest Hyperion 20F / -6C sleeping bag-Regular (203 cm)-Deep Pacific
Delivery by 16 June $64.36
Hyperion 20F/-6C Deep Pacific
Free delivery
originally posted on cascadedesigns.com
A number of years ago I purchased a Hyperion 0 deg bag to replace a worn out old favorite. The Hyperion quickly turned into my new go to bag. Warm, very light, and quite roomy. It also became a favorite of my wife's for bike packing. This year I decided to get the Hyperion 20 for warmer trips. Only drawback is securing it from my wife who currently has it on a pack raft trip! Cascade Designs truly nailed it with Hyperion line up!
originally posted on cascadedesigns.com
Just got back from using this sleeping bag on an Alaskan fly-in hunt for sheep and black bear near Delta Junction. After 10 days of usage, I would rate the bag an overall of 5 stars.Things most people don’t consider… this bag is rated for 32F comfort (ideal use temps), 20F limit (lowest you want to use it) and -9F risk (you might get severely injured). The hunt was low 30s to high 20s at night and the bag never had me more than slightly chilled, wearing only merino wool base layers. I would agree that this bags comfort limit is about 32F.Another reviewer gave this bag a very low rating as it wasn’t warm enough, then went on to say they wore several layers of clothes in the bag. This is not ideal. In a sleeping bag, especially compact ones like this, it’s a best ... MoreJust got back from using this sleeping bag on an Alaskan fly-in hunt for sheep and black bear near Delta Junction. After 10 days of usage, I would rate the bag an overall of 5 stars.Things most people don’t consider… this bag is rated for 32F comfort (ideal use temps), 20F limit (lowest you want to use it) and -9F risk (you might get severely injured). The hunt was low 30s to high 20s at night and the bag never had me more than slightly chilled, wearing only merino wool base layers. I would agree that this bags comfort limit is about 32F.Another reviewer gave this bag a very low rating as it wasn’t warm enough, then went on to say they wore several layers of clothes in the bag. This is not ideal. In a sleeping bag, especially compact ones like this, it’s a best practice to only wear your base layers and nothing more. When you start layering up, you won’t allow the down to insulate your body and trap heat, making you colder. I actually tested this, one night wearing three layers and found it very cold. Next nigh, only base layers, and was much warmer.
originally posted on cascadedesigns.com
6'0",180. I really wish I could have given 4.5 stars, but alas....I've used this bag for two summers now. Put about 800 miles on it. In order to get the insane lightweight it is understood there will be a couple of compromises... fits snug, just enough insulation, short zipper. This bag packs down extremely small. I sleep pretty warm and though other 20° bags might be warmer this one actually works at 20°, but not much lower. The only complaint I have is that the zipper is just a little short. Another 6 in would make all the difference. With the zipper as is, it is more difficult to use as a quilt (in warmer temps).
| EN Comfort | 32F |
| EN Limit | 20F |
| Regular | 1 lb 4 oz |
| Long | 1 lb 6 oz |
| Temperature Rating | 20 Fahrenheit |
Therm-a-Rest Hyperion 20F/-6C Ultralight Down Mummy Sleeping Bag
Affiliate Disclosure: We may receive a small commission for purchases made through this link at no extra cost to you. This helps support our site. Thank you!
Therm-a-Rest Hyperion 20F / -6C sleeping bag-Regular (203 cm)-Deep Pacific
Delivery by 16 June $64.36
Hyperion 20F/-6C Deep Pacific
Free delivery
A number of years ago I purchased a Hyperion 0 deg bag to replace a worn out old favorite. The Hyperion quickly turned into my new go to bag. Warm, very light, and quite roomy. It also became a favorite of my wife's for bike packing. This year I decided to get the Hyperion 20 for warmer trips. Only drawback is securing it from my wife who currently has it on a pack raft trip! Cascade Designs truly nailed it with Hyperion line up!
Just got back from using this sleeping bag on an Alaskan fly-in hunt for sheep and black bear near Delta Junction. After 10 days of usage, I would rate the bag an overall of 5 stars.Things most people don’t consider… this bag is rated for 32F comfort (ideal use temps), 20F limit (lowest you want to use it) and -9F risk (you might get severely injured). The hunt was low 30s to high 20s at night and the bag never had me more than slightly chilled, wearing only merino wool base layers. I would agree that this bags comfort limit is about 32F.Another reviewer gave this bag a very low rating as it wasn’t warm enough, then went on to say they wore several layers of clothes in the bag. This is not ideal. In a sleeping bag, especially compact ones like this, it’s a best ... MoreJust got back from using this sleeping bag on an Alaskan fly-in hunt for sheep and black bear near Delta Junction. After 10 days of usage, I would rate the bag an overall of 5 stars.Things most people don’t consider… this bag is rated for 32F comfort (ideal use temps), 20F limit (lowest you want to use it) and -9F risk (you might get severely injured). The hunt was low 30s to high 20s at night and the bag never had me more than slightly chilled, wearing only merino wool base layers. I would agree that this bags comfort limit is about 32F.Another reviewer gave this bag a very low rating as it wasn’t warm enough, then went on to say they wore several layers of clothes in the bag. This is not ideal. In a sleeping bag, especially compact ones like this, it’s a best practice to only wear your base layers and nothing more. When you start layering up, you won’t allow the down to insulate your body and trap heat, making you colder. I actually tested this, one night wearing three layers and found it very cold. Next nigh, only base layers, and was much warmer.
6'0",180. I really wish I could have given 4.5 stars, but alas....I've used this bag for two summers now. Put about 800 miles on it. In order to get the insane lightweight it is understood there will be a couple of compromises... fits snug, just enough insulation, short zipper. This bag packs down extremely small. I sleep pretty warm and though other 20° bags might be warmer this one actually works at 20°, but not much lower. The only complaint I have is that the zipper is just a little short. Another 6 in would make all the difference. With the zipper as is, it is more difficult to use as a quilt (in warmer temps).
Incredibly light, surprisingly warm, packs down remarkably small. Biggest two issues are zipper related. The small zipper is a pain to use, and their is insufficient protection to ensure you don't tear the VERY thin materials with the zipper. I use more care than I should every time I zip and unzip this thing. Overall, I'm happy with it. If weight and pack size are your top priorities, and you still want a bag, not quilt, this is your bag.
I've had my Hyperion 20 now for two summers and it has been amazing. I did a ton of research before buying this bag as it was my first time purchasing a down bag of this quality. I settled on the Hyperion due to its lightness and compactness. It is both of these things and more. I am a 3-season backpacker in Washington and a 20 degree bag felt like the right call in terms of warmth. I have used my bag in temps ranging from 15-45 degrees and it has performed flawlessly. Paired with an insulated air pad for shoulder season and a closed cell pad for summer I have found this bag to suit all temps. The few times my bag has gotten slightly wet from tent condensation or dew it has dried extremely quickly and I did not feel any cold spots. It is a narrow foot box and ... MoreI've had my Hyperion 20 now for two summers and it has been amazing. I did a ton of research before buying this bag as it was my first time purchasing a down bag of this quality. I settled on the Hyperion due to its lightness and compactness. It is both of these things and more. I am a 3-season backpacker in Washington and a 20 degree bag felt like the right call in terms of warmth. I have used my bag in temps ranging from 15-45 degrees and it has performed flawlessly. Paired with an insulated air pad for shoulder season and a closed cell pad for summer I have found this bag to suit all temps. The few times my bag has gotten slightly wet from tent condensation or dew it has dried extremely quickly and I did not feel any cold spots. It is a narrow foot box and overall not a roomy sleeping bag, but for someone like me who picks a sleep position and sticks with it I have not felt claustrophobic in this bag. Straps on the bottom connect to your pad to stop any sliding around. In terms of pack-ability and weight I believe the Hyperion to be top of its class. I purchased a 5L Sealine BlockerLite compression dry sack for the Hyperion and the bag fits perfectly inside and compresses even smaller than with the compression sack it came with. Plus I have the piece of mind that my bag will stay dry no matter what. Overall, if you are searching for a down backpacking bag I would highly recommend the Hyperion 20!
Bought this on sale thinking ut might be warm enough for what I was looking for. I was WAY wrong. Almost no insulation on the back (its so thin you can see light and down clumping inside) so if you are a side sleeper you have nothing keeping your back warm. I used it in 45-50° F spring nights and with clothes on still froze. I even slept on a cot inside the house where ut was 65° in boxers and was freezing. I an usually a warm sleeper anyways so I was quite surprised and disappointed. Tried contacting customer service and they said TWELVE + weeks before I could expect a response. Well its been about that long and nothing. Bought it in March and now its July so no 90 day money back guarantee probably. Very dissatisfied. Do not buy this bag unless you plan to only ... MoreBought this on sale thinking ut might be warm enough for what I was looking for. I was WAY wrong. Almost no insulation on the back (its so thin you can see light and down clumping inside) so if you are a side sleeper you have nothing keeping your back warm. I used it in 45-50° F spring nights and with clothes on still froze. I even slept on a cot inside the house where ut was 65° in boxers and was freezing. I an usually a warm sleeper anyways so I was quite surprised and disappointed. Tried contacting customer service and they said TWELVE + weeks before I could expect a response. Well its been about that long and nothing. Bought it in March and now its July so no 90 day money back guarantee probably. Very dissatisfied. Do not buy this bag unless you plan to only sleep outside on 60°+ nights with layers. Price for performance is ridiculous.
I received the Hyperion 20 a few weeks ago and headed out to the backcountry short after. After the first night I noticed a tear on the outside of the bag. The temperature dropped to 20, however, though combining with a NeoAir XTherm on top of a RidgeRest I couldn’t get a good night sleep.Thermarest did great in creating an extremely light sleeping bad. Sadly it does not hold up to the standards I’ve set based on years of experience with high performance gear from them.Hope I can continue to purchase with confidence also in the future.
Does exactly what it says. It really is the best, warmest and lightest bag, as long as you follow the rules.1. Sleep on your back. If you want to roll over, your back will be cold. The bag has much less fill in the back, so no side sleeping or moving around.2. Lie like a mummy. It is pretty tight in there to keep it efficient. If you want to move your arms around, you will not love it.In the end, I found that I cannot follow these rules and I find myself chilly much of the time. Great bag for the ultralighter that pounds out the miles and follows the rules. For me, a little heavier weight would be worth the comfort.Quality of the build is great. The bag is magically light and packs into almost nothing.
Took this for two overnight camping, both at around 32F. It is really lightweight and can be compressed so small. Impressive at first sight. But I wanna go on with its shortcomings.Pair it with a Xlite pad. The first night is good, but probably because we had baselayer on and had placed several hand warmer pack in the sleeping bag. The second night I just had my underwear and was so frozen that I had to leave the tent to get into my car (Glad we are doing car camping the second night). I carefully checked the bag and it was very easy to spot voids of insulation, even after we tried to redistribute the down before sleeping. The reason is simple: there is so little insulation which is exactly the reason why it is so lightweight.I understand that a 32F sleeping bag ... MoreTook this for two overnight camping, both at around 32F. It is really lightweight and can be compressed so small. Impressive at first sight. But I wanna go on with its shortcomings.Pair it with a Xlite pad. The first night is good, but probably because we had baselayer on and had placed several hand warmer pack in the sleeping bag. The second night I just had my underwear and was so frozen that I had to leave the tent to get into my car (Glad we are doing car camping the second night). I carefully checked the bag and it was very easy to spot voids of insulation, even after we tried to redistribute the down before sleeping. The reason is simple: there is so little insulation which is exactly the reason why it is so lightweight.I understand that a 32F sleeping bag does not mean exactly you can be comfortable at 32degree, and I believed that it would be much better that night if I have my baselayer on. However, just be cautious that this is more like a summer bag rather than a 3-season bag. If you are still doubting about it, read the reviews on outdoorgearlab, which I wished I had read before buying it.
Actually a really good sleeping bag. I am 1.73cm tall and quite slim and the sleeping bag fits well. I slept plenty of nights in the sleeping bag and never felt cold when the outside temperature dropped to near 0°C (on a prolight plus) . However the biggest downside of the sleeping bag is the very short zipper, so you cannot open the sleeping bag far enough to use it more like a blanket which would be useful for very warm night( 18°C and more). Also the zipper is a bit tricky you need to be careful when using it. If you could open the zipper at least 50cm further it would be the perfect 3 season sleeping bag.
| EN Comfort | 32F |
| EN Limit | 20F |
| Regular | 1 lb 4 oz |
| Long | 1 lb 6 oz |
| Temperature Rating | 20 Fahrenheit |
