Or, he just doesn't like feeling trapped in a sleeping bag. I don't, and I can tell you that I definitely do not have an anxiety disorder. Since I treat those a lot, I know what they are, and what the symptoms are, and not everyone who dislikes closed-in spaces meets those criteria. If he's not freaking out in cars, small rooms, crowded places, or experiencing anxiety in other settings - nope.
Just give the guy a pass to use the bag unzipped and let him breath easier.
test the bag at home. unzipped and zipped. It's the first step. If that's ok, and then at altitude, when it's cold out, see what happens. Quilt might be the answer, but.. you never know. I was feeling a bit trapped in my older REI bag, but heck, I know I need to be warm. That's when it becomes a mental game i guess. I choose warmth. It didn't matter to my friend zipped or unzipped above 8200'.
BTW, I don't know anyone that I hike with who cinches up their bag completely in the Sierra during the high season, unless It's really friggn cold. My badger is always unzipped.
Once when fully zipped up and hood fully cinched, I must have woke up from a dream and my zipper stuck and I freaked out. I was not alone so my tent partner "saved me" before I tried to rip the bag apart. When I had poor sleeping bags the zippers would always stick, so I became quite anxious. Now I have a Western Mountaineering bag - cost a bloody fortune, but they sure have well designed zippers and zipper baffles. I have never once had a stuck zipper in this bag. I have been told, if you are right handed, get a left zip bag, and if left handed, a right zip bag. This seems to work for me.
Yes, I am one of those ultra-cold sleepers. I totally zip up and cinch the hood on my 5-degree Western Mountaineering bag in the Sierra as soon as it hits 40-degrees.
My pseudo-claustrophobia depends on how restricted my arms are. I can be in a small space, but the minute I cannot freely move my arms, I get a bit freaked. I do not like small caves! But like others said, it is a mental exercise - I have learned to deal with my sleeping bag. I really like to be warm. It takes a few nights out before I sleep well.
I have to admit, at times I felt claustrophobic in my mummy bag. Last year I got a Sierra Designs Backcountry and love it. Super roomy and comfortable.
By the way - if you use them properly, you don't get cold in quilts any more than you do in a bag. They are actually easier to tuck in snugly, not having miles of fabric or zipper teeth to get in the way.
Don't expect your friend's anxiety to respond to logic or reason. Anxiety and fear are often triggered by the Amygdala, the primitive part of the brain that initiates the flight or flight response. When this part of the brain dumps a flood of adrenalin into the system, you feel a response that's good for survival, but not always pleasant. Picture walking around a corner and seeing a Bengal tiger. Adrenalin rush! Or it can be fun, like Bungee jumping. Context has a lot to do with it.
Things go wrong when being confined in a sleeping bag (or spiders, snakes, heights, etc.) stirs up this survival mechanism. It may not be logical, but however the mental association occurs, it feels very real to the person who's experiencing this. Now you can go into a psychological process called "desensitization", where you're gradually exposed to the stimulus which provokes the anxiety until the response abates (is extinguished) but that's rather involved, and likely unnecessary. Of course, your friend could practice using a sleeping bag at home, in comfortable, familiar circumstances. That would be similar.
Practically speaking, it's probably better to go around this problem than through it. Quilts are great, and becoming more popular all the time! Katabatic and other companies make quilts which are much less confining, but are warm down to zero centigrade. That could be an easy solution for your friend, if that's actually the main source of anxiety. Keep in mind how, especially for newbies, sleeping outdoors itself can stir up a bit of trepidation. Also hunger, dehydration, fatigue, gaining altitude too quickly, caffeine, etc. can contribute to feelings of anxiety
There was a recent post on this board about sleeping bags vs quilts. A large percentage of backpackers expressed unpleasant feelings of confinement, anxiety, claustrophobia, etc. with mummy-style sleeping bags. Personally, I don't like the restricted feeling of using a mummy bag. I use my mummy bag as a quilt most of the time, even when winter camping. Now the funny thing I've noticed, when it gets colder as the night goes on, it feels much more comfortable to zip up and snuggle inside the bag. So go figure.
I've worked as an addiction counselor, and for anyone having problems with anxiety, I would not recommend jumping right onto the medication merry-go-round. The side effects can be noxious and unpredictable. There's a good self-help book called "The Anxiety and Phobia Workbook" by Edmund Bourne (New Harbinger Press) that describes very sound principles for developing an integrated, lifestyle approach to dealing with anxiety. For serious, recurring problems, "Cognitive-Behavioral Therapy" is a respected, sensible therapeutic method.
I certainly hope your friend doesn't think they have to give up the glories of backpacking in the Sierra just because of the commonplace, unpleasant experience that many people have with mummy bags.
I like a bag with a full length zipper. I start out with it almost completely unzipped and laying on me like a blanket. As the temps drop I start to zip it up. Only when it is the coldest is it zipped up around my chest. I sleep in long tops and bottoms so I don't feel drafts directly on bare skin.
