The present study assessed the role of the time judgement paradigms of prospective and retrospective durations, the length of durations and the effects of the states of mood and arousal in time perception. The role of the biological variable of circadian types was also assessed. Long target durations were judged as shorter than whereas short target durations were judged as longer. Duration judgement paradigms did not affect perception of time and neither did mood and circadian type. It was not possible to assess the relationship between arousal and time perception, because the sample contained individuals (except for 2 people) who belong to the same group based on their arousal levels. It is proposed that time estimation paradigms, methods, and duration of target intervals all play a role in time perceptions creating a context-rich or context poor interval and duration is probably more influential than has previously been thought. The longer the duration the more time is allowed for information processing and even when a participant primarily attends to the target duration he or she still takes in information from the environment, and also from the internal environment as he or she is conscious of her mood, emotions and thoughts. These variables are impossible to control at the same time. Therefore, for the time being no new model can be proposed which may describe accurately all the processes during the perceiving of time. Mood and circadian type were not found to affect time perception, but it is likely due to methodological shortcomings of the present study.