I sometimes keep a diary, for example when I go on long trips that are different from my day-to-day life. I try to be as accurate as possible, but sometimes i notice what i write isn't fully representative of my state of mind at the time, simply because when you're writing stuff down (especially when you're writing with a pen and paper (slow!)), you can never fully capture all the concurrent thoughts and emotions you're experiencing, so its impossible for a diary to be fully accurate. Undoubtedly, e.g. Elizabeth Loftus has done a lot of prominent research in that field, our memories tend to be fallible, but maybe that's part of the reason?
