Of course, it can be any of the things mentioned in the site above.

Balance can be a big cause as can things left around to trip over as well as failing eyesight,  maybe if your sleeping pills are making you foggy you may need different ones.

I find that while in bed lying on my back that having a BIG stretch then relax and do some deep breathing helps a LOT also if you have something on your mind that is keeping you awake try having a radio or a TV that you can set up to turn off automatically --with whatever suits -- music or a program and that takes your mind off things 

I do get funny turns now and then as I call them - lose my balance and almost fall - suddenly usually as turning around to walk another way in the house. Luckily.  

Nasty and I take Stemetil tablets for it. Works a treat.  Need a script from the doctor though.