upper back spasms and aches

My upper back, including around the middle back has a lot of spasms and aches that bother me.  I have them off and on only lately constantly.  They usually occur at night when I'm in bed..  What could be causing them.

[Adam Tanase, D.C.]

Poor posture throughout the day, or irregular sleeping positions due to too many pillows, the wrong pillow, or a improperly supportive mattress. This, of course, is the most basic explanation of what *could* be causing it... You might consider visiting a local chiropractor and receiving a spinal examination for a more conclusive answer.

Warm wishes,
AT