Don't think of it as strange, think of it as normal.

We all have experienced this, and this 'blackness' or 'nothingness' you have described, has gone on in me for certain periods of time for up to a month! We call it a 'dry spell' if it goes on for a week or so.

There are many individual nights, where this happens to me, so don't worry! You'll be ok...

Also, how much sleep did you get last night? Did you take any medication for a cold? are you on any Antidepressants? ...and how stressed out are you?
If any of the above are the case, then that might have dulled your sleep, because you would have been deeper into it...or in the case of stress...not deep enough.