I had vertigo for about a month a few months ago. Another friend (in Australia) mentioned he had it as well when I tweeted about it. It can be caused by a virus. Your immune system gets whacked when you don't rest properly, so it's possible you had the same thing that was going around.

Try ditching the phone/computer after 8PM and just relax and enjoy life. There will always be more work to do in the morning.