It does not hurt the unit in anyway.
Hibernate is just sleep, but with the data on the hard drive so that no power is needed. This means that on startup that data is just read into memory and the system resumes whatever it was doing before the hibernation.
Windows 8's quick boot is based on hibernation in fact(shut down on 8 is logoff + hibernate).
I used to use hibernate all the time when I had a laptop for school since it was a good way to leave things open(saved first) over the time between classes without killing the battery.