You certainly can set your time zone.
Go to your profile (either by clicking on your name or by clicking on profile on the menu underneath the SB) and do the following :
1) Select Look and Layout from the options under Modify Profile in the left hand menu.
2) Find Time Offset in the list that appears.
3) Try using autodetect first of all and see if that updates the time to your local time zone.
If so then - Done! :)
If not, then go back to the Time Offset option and alter it to suit your time zone.