Its not xray vision but its a start

Amazing the stuff you can find on the web:How to See in the Dark - WikiHow

1. Take advantage of the structure of your eyes. The human eye has 'rod' cells and 'cone' cells on the retina, which is the sensory layer at the back of the eye. Rod cells and cone cells are distributed evenly throughout the retina except for the fovea, which is a small area on the back of the eye directly opposite the pupil. At the fovea, there are only cone cells. This is an important thing to know because the 'cone' cells are more proficient at color detection, whereas 'rod' cells are better for low light and detecting movement. Therefore, when trying to see in low light, try not to look directly at the places you are trying to see. By using your peripheral vision you are using more rod cells, which work much better in low light. This takes a great deal of practice for most people.
2. Keep your eyes adjusted for the dark. If you're in a lighted area and know you're going to be going into a dark area, close your eyes tightly, or at least squint your eyelids before entering the dark to give your eyes a chance to adjust. If you can't close both eyes, close one or place a hand over one. This works well when driving into tunnels. Once you're in, avoid looking directly at any light source, no matter how dim you think it is. It takes longer to adjust back for the dark than it did for your eyes to adjust for the light you just looked at.
3. Practice. This can be as simple as shutting out the lights in a room and closing all portals, allowing only the ambient light that slips in under the door. One place to work at it is in the bathroom while taking a shower. You've probably been showering in the same room for years and can practically navigate it with your eyes shut. Most bathrooms don't have a large amount of windows, so there's less light coming in. Just be careful and take it slow. All it takes is one rug in the wrong place and you could fall, hit your head on the edge of the tub, and drown in an inch of water.
4. Scan, don't stare. If you look at something, or a place, in the dark for too long, your eyes will become less sensitive to what little light there is. If you scan your eyes back and forth over the area you are looking at, you will be using different areas of "rods" as described above, and you will be able to see details clearer.
5. Protect your night vision. If you do need to use a light, having a coloured lens over the light will help preserve your night vision. White light, containing all frequencies, from red all the way to blue, will ruin your night vision the fastest. Blue lenses work best; red lenses are the worst, but anything is better than white light. A good way to have a light source that is easy on your night vision is to buy a blue LED flashlight. The lit tip of a cigarette will thoroughly trounce your night vision - it's that sensitive.
   

How to See in the Dark - WikiHow