The effect of cannabis on perception of time: a critical review.

The survival of any organism, animal or human, relies on the ability to accurately process, sense or tell time. Emerging evidence shows that timing is a crucial element in most, if not all, cognitive functioning and motor behaviour. Advances made by timing researchers provide valuable information on the neural substrates of interval timing, which indicate the involvement of certain brain areas and networks, most of which have not only been implicated in conditions such as schizophrenia, but are also abundant with cannabinoid receptors. A distorted sense of time is one of the most common effects of cannabis reported by users. In this paper, we present a critical review of the existing research on the topic. The findings are inconclusive, mainly due to methodological variations and the paucity of research. Even though 70% of time estimation studies report over-estimation, the findings of time production and time reproduction studies remain inconclusive. More research with robust methods is required to reach conclusions about the precise effect of cannabis and its active compounds on time perception. Such studies may also lead towards a better understanding of the mechanisms involved in brain functioning.