Perception of time or conception of time

Earlier tonight at dinner my roommates girlfriend and I had a dissagreement about which is the proper phrase for losing track of time. She was talking about a gathering from two nights ago when she was having so much fun that her conception of time was off and she didn't realize how late it was. I told her that she should've said that her perception of time was off. She insisted that coception was the correct way while I stayed with perception. My roommate agreed with me while our other friend at the table agreed with her. I've looked at numerous sites on the internet but have yet to find anything that answers this. Although I did find more sites that dealt with time perception than time conception. Please help us settle this if you could.