In 1991, a pharmacologist by the name of M.E. West who worked at the University of the West Indies which was located in Kingston, Jamaica, suggested that the local fisherman who smoked cannabis or consumed it via a cannabis infused white rum were able to see exceptionally well at night. This gave them the ability to navigate through the treacherous coral reefs that surrounded the docking area.
After going out with the local fisherman on a nighttime fishing trip M.E. West said “It was impossible to believe that anyone could navigate a boat without a compass and without light in such treacherous surroundings,” “[but] I was then convinced that the man who had taken the rum extract of cannabis had far better night vision than I had, and that a subjective effect was not responsible.”
Some of the local fishermen told M. E. West that Moroccan fishermen and mountain dwellers experience a similar improvement after smoking hashish, and in 2002, another research team traveled to the Rif mountains in Morocco to investigate further.
In order to actually test if cannabis did have a positive effect on night vision they gave a synthetic cannabinoid to one volunteer, and hashish to three more, then used a newly developed piece of kit to measure the sensitivity of their vision in a nighttime environment. Confirming the Jamaican fishermen and M. E.West’s earlier report, they found that cannabis improved night vision in all three of their test subjects.
In a study recently published in the journal eLife, a group of researchers offer a potential answer. To see what marijuana was doing to eye cells, Lois Miraucourt and co-authors decided to test the effect of cannabis to these cells on tadpoles of the African clawed toad (previous research has shown that the retinas of these frogs have cannabinoid receptors).
As Mo Costandi writes in The Guardian, the tadpoles “are transparent and, therefore, amenable to all sorts of experiments that cannot be performed in humans or other lab animals.” That makes it easy to see what exactly is happening in the tadpoles.
Conclusion
Basically, the results showed that retinal ganglion cells, essential inner eye neurons, become more sensitive to light after being exposed to cannabis. The tadpoles themselves showed better ability to distinguish contrast after that exposure as well. When I was younger my mum used to tell me to eat my greens if I wanted to be able to see in the dark, however these studies suggest that all you really need to do is smoke it!