I suppose you could get some thin sheets of plywood or MDF and cover up the whole thing floor to ceiling. Attach them top and bottom, add some paint and you've got yourself a new fake wall.

chinese curtain?

Removeable wallpaper. Or use starch or flour (i read something about it here once) as a paste to attach fabric to wall.

A room divider perhaps nailed to the wall?
Maybe something like this: http://www.ikea.com/us/en/catalog/products/70182191/

Make an 8' x 8' upholstered headboard using (2) 4'x8' pieces of 1/4' plywood, each covered with foam (those memory foam mattress pads are awesomely comfortable as a headboard lining) and then wrapped/upholstered (can use drapery panels if you take out the stitching for the header, hem and side hems and just wrap each plywood piece). Do them separately, and then use that really sticky velcro (can get it at Lowes) and attach them together with about (5) 18" pieces (9" on each panel, and then an 18" piece to hold them together) AND then to the window/wall behind. This will be easier with two people as the panels are kind of wobbly but if you use thicker plywood, they'll be so dang heavy you will have a hard time maneuvering them.

Put your bed and nightstand against the new 'headboard'. You can even attach reading lights to the headboard (cut holes and run cords behind). The combination of the velcro and bed tucked against the headboard will keep it in place. The padding and upholstery will block noise and light.

Let me know if you end up doing this - and post pics!

uh-oh. Plywood pieces are 4'x8' by 1/4", not 1/4'! Sorry ;)

Just get a gorgeous swatch of fabric and hang it draped over a dowel above and behind the bed. --it'll give you a beautiful airy feel and a nice visual break from the non operational door. Plus no one will know but you :)

Regarding the starch/paste comment, its from Daniel the genius behind Manhattan Nest (instructions here) http://manhattan-nest.com/2010/06/01/the-doors/

However, as your doors are already frosted this seems a little pointless. If you do decide to make something upholstered (which is totally achievable for a novice btw) I'd suggest you 1) buy an electric staple gun and 2) consider metal mending plates as supports behind the panels. http://www.google.com/products/catalog?hl=en&rlz=1C1ECSA_enUS465US465&q=metal+mending+plates&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&ion=1&biw=1366&bih=603&um=1&ie=UTF-8&tbm=shop&cid=8260977161370129680&sa=X&ei=-QMIT5azBomriQLO9dTECQ&ved=0CFcQ8wIwAwThey are cheap, available at any hardware store, and easily applied to the hidden back of your project with a drill.

If you want to kill any noise coming through, a thick upholstered headboard is definitely you best bet. :)

If you're anti-handy or don't like that idea, you could also put a very tall bookshelf behind the bed. Except I suppose you wouldn't want books in it if you live somewhere you might get earthquakes- maybe put some pretty pillows and soft things in it instead?

If you're handy you can build a temporary sheetrocked wall to cover up the glass doors - or you can hire a carpenter to build one for you. I've seen this done and it looked great. The frame is nailed or screwed to the floor and ceiling, but only in a few places. When it came time to move, it was torn down. It's a biggish project, but may be worth it if you're going to be there for a few years. You can paint it any color you want, hang things on it like any sheetrocked wall.

i'm curious: if it's a glass double door leading into the bedroom area i'm assuming you have another entry door to the bedroom since you plan to cover this one up? what was the designer of this loft thinking!? you're right to NOT put your bed up against the glass door without first taking care of the feng shui problem. I do think a temporary sheetrocked wall is the best solution since you want noise proofing, too. Another idea is you could build a custom Shoji screen and use plain or fancy paper. Good luck!

The folding screen behind the bed in the picture is pretty nice. Why not try something like that?

You can get 2" thick foam insulation panels at a big box home improvement store... that's what my husband and I used to block a set of french doors between our master & 2nd bedroom. They're about 2 feet wide, so we basically hot glued them together, trimmed a few inches from the bottom, stapled a flat sheet over the whole thing, and wedged the whole panel into the door frame (we did have to scoop out a little hole for the doorknob, but otherwise it was a pretty good fit). It's not soundproof, but the sound blocking is comparable to the other walls in our house. We do have a set of curtains in front of it, but it would look fine behind a headboard or something if you centered the bed on it or put a screen in front of it.

You don't want fabric, and you need to shut out a draft under the doors as well as light? A photo and the size of the space would help a lot. I say there is nothing wrong with putting a bed in the center of a space away from the dreaded unwanted doors.