Twice I'v woken at night to the sound of a camera whirring in my ear as if one is right there next to me. WHen I look around there's nothing there. Maybe I'm dreaming?

I think you may be dreaming also.

Or you could have a medical condition called tinnitus.
It's a buzzing, whistling or whirring in your ear. The cause may be traced to a variety of ills.
If it persists, go to an audiologist and have your hearing checked.
If you are exposed to loud sounds (machinery, gun fire, loud music, etc.) it may have affected your hearing.

I concur with the ugly cat. - I've had this problem too. Hold an air horn too close to your ear and well.. Heh.. Sufficed to say, you regret it.

It sounds more like you have a problem with your ear like everyone else has said, I've had similar experiences lately with one of my ears, when I lie down it sounds like I can hear marching going on. Its all because I had a blocked ear a few weeks ago and had the wax pumped out and it had some funny after affects for a few days.

Your pulse...

Defo try a hearing specialist though.

Thanks I did consider going back but its ok now. Maybe analog_warrior should see one if there still having the same problem though.

I concur with the ear problem thingy. I have tinnitus and hear a high pitched drone from time to time. It could also be caused by an affliction called TMJ, in which the cartilage from your jaw actually begins to grow into your ear canal. I suggest seeing a doc.